Fixes #35 (Dropbox handlers), Fixed FTP response reading length

Added FTP Recursive listing, Implemented ftp search
- Implemented FTP full directory remove - Fixed FTP STOR bug - Implemented relativePath(of:) for FTP - Initial implementation of FTP active mode
2017-04-14 11:15:09 +04:30 · 2017-04-11 22:21:13 +04:30 · 2017-04-11 19:43:34 +04:30 · 2017-04-09 14:09:03 +04:30 · 2017-04-05 02:05:28 +04:30 · 2017-04-05 00:24:24 +04:30
40 changed files with 5950 additions and 2368 deletions
@@ -1,32 +1,80 @@
 language: objective-c
-
 osx_image: xcode8.2
-
-xcode_project: FileProvider.xcodeproj
+xcode_project: $PROJECTNAME.xcodeproj
 env:
  global: 
-    - PROJECTNAME="FileProvider"
-    - FRAMEWORK_NAME="FileProvider.framework"
+  - PROJECT="$PROJECTNAME.xcodeproj"
+  - FRAMEWORK_NAME="$PROJECTNAME.framework"
+  - IOS_FRAMEWORK_SCHEME="$PROJECTNAME iOS"
+  - MACOS_FRAMEWORK_SCHEME="$PROJECTNAME OSX"
+  - TVOS_FRAMEWORK_SCHEME="$PROJECTNAME tvOS"
+  - IOS_SDK=iphonesimulator
+  - MACOS_SDK=macosx
+  - TVOS_SDK=appletvsimulator
  matrix:
-    - SHCEME="FileProvider OSX" SDK="macosx" ACTION="build"
-    - SHCEME="FileProvider iOS" SDK="iphonesimulator" ACTION="build"
-    - SHCEME="FileProvider tvOS" SDK="appletvsimulator" ACTION="build"
+    - DESTINATION="OS=10.2,name=iPad Air 2"        SCHEME="$IOS_FRAMEWORK_SCHEME"     SDK="$IOS_SDK"     RUN_TESTS="NO" BUILD_EXAMPLE="NO" POD="YES" CARTHAGEDEPLOY="NO"
+    - DESTINATION="OS=9.0,name=iPhone 6"           SCHEME="$IOS_FRAMEWORK_SCHEME"     SDK="$IOS_SDK"     RUN_TESTS="NO" BUILD_EXAMPLE="NO" POD="NO"  CARTHAGEDEPLOY="YES"
+    - DESTINATION="OS=8.1,name=iPhone 4S"          SCHEME="$IOS_FRAMEWORK_SCHEME"     SDK="$IOS_SDK"     RUN_TESTS="NO" BUILD_EXAMPLE="NO" POD="NO"  CARTHAGEDEPLOY="NO"
+
+    - DESTINATION="OS=10.1,name=Apple TV 1080p"    SCHEME="$TVOS_FRAMEWORK_SCHEME"    SDK="$TVOS_SDK"    RUN_TESTS="NO" BUILD_EXAMPLE="NO" POD="NO"  CARTHAGEDEPLOY="NO"
+    # - DESTINATION="OS=10.0,name=Apple TV 1080p"    SCHEME="$TVOS_FRAMEWORK_SCHEME"    SDK="$TVOS_SDK"    RUN_TESTS="NO" BUILD_EXAMPLE="NO" POD="NO"  CARTHAGEDEPLOY="NO"
+
+    - DESTINATION="arch=x86_64"                    SCHEME="$MACOS_FRAMEWORK_SCHEME"   SDK="$MACOS_SDK"   RUN_TESTS="NO" BUILD_EXAMPLE="NO" POD="NO"  CARTHAGEDEPLOY="NO"
 before_install:
  - gem install xcpretty --no-rdoc --no-ri --no-document --quiet
-  - brew update
-  - brew outdated carthage || brew upgrade carthage
+  - gem install cocoapods --no-rdoc --no-ri --no-document --quiet
+  # - gem install xcpretty-travis-formatter
+
 script:
-  - set pipefail
+  - set -o pipefail
  - xcodebuild -version
-  - xcodebuild -project $PROJECT.xcodeproj -scheme "$SCHEME" -sdk $SDK $ACTION ONLY_ACTIVE_ARCH=NO | xcpretty
-#  - pod lib lint --quick
-# after_success:
+
+  # Build Example in Debug if specified
+  - if [ $BUILD_EXAMPLE == "YES" ]; then
+      xcodebuild -project "$WORKSPACE" -scheme "$EXAMPLE_SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Debug ONLY_ACTIVE_ARCH=NO build | xcpretty;
+    fi
+
+  # Build Framework in Debug and Run Tests if specified
+  - if [ $RUN_TESTS == "YES" ]; then
+      xcodebuild -project "$PROJECT" -scheme "$SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Debug ONLY_ACTIVE_ARCH=NO ENABLE_TESTABILITY=YES test | xcpretty;
+    else
+      xcodebuild -project "$PROJECT" -scheme "$SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Debug ONLY_ACTIVE_ARCH=NO build | xcpretty;
+    fi
+
+  # Build Framework in Release and Run Tests if specified
+  - if [ $RUN_TESTS == "YES" ]; then
+      xcodebuild -project "$PROJECT" -scheme "$SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Release ONLY_ACTIVE_ARCH=NO ENABLE_TESTABILITY=YES test | xcpretty;
+    else
+      xcodebuild -project "$PROJECT" -scheme "$SCHEME" -sdk "$SDK" -destination "$DESTINATION" -configuration Release ONLY_ACTIVE_ARCH=NO build | xcpretty;
+    fi
+
+  # Run `pod lib lint` if specified
+  - if [ $POD == "YES" ]; then
+      pod lib lint --quick;
+    fi
+
+after_success:
+  # Run `pod trunk push` if specified
+  - if [ $POD == "YES" ] && [ -n "$TRAVIS_TAG" ]; then
+      pod trunk push --allow-warnings;
+    fi
+
 #   - bash <(curl -s https://codecov.io/bash)
 before_deploy:
-  - carthage build --no-skip-current
-  - carthage archive $PROJECTNAME
+  - if [ $CARTHAGEDEPLOY == "YES" ] && [ -n "$TRAVIS_TAG" ]; then
+      brew update;
+      brew outdated carthage || brew upgrade carthage;
+      carthage version;
+      carthage build --no-skip-current --verbose;
+      carthage archive $PROJECTNAME;
+    fi
+
 deploy:
-  file: $PROJECTNAME.framework.zip
+  provider: releases
+  api_key: "$GITHUBTOKEN"
+  file: $FRAMEWORK_NAME.zip
  skip_cleanup: true
  on:
-    tags: true
+    repo: amosavian/$PROJECTNAME
+    tags: true
+    condition: "$CARTHAGEDEPLOY = YES"
@@ -16,8 +16,8 @@ Pod::Spec.new do |s|
  #

  s.name         = "FileProvider"
-  s.version      = "0.11.4"
-  s.summary      = "FileManager replacement for Local and Remote (WebDAV/Dropbox/OneDrive/SMB2) files on iOS and macOS."
+  s.version      = "0.15.5"
+  s.summary      = "FileManager replacement for Local and Remote (WebDAV/FTP/Dropbox/OneDrive/SMB2) files on iOS and macOS."

  # This description is used to generate tags and improve search results.
  #   * Think: What does it do? Why did you write it? What is the focus?
@@ -35,6 +35,9 @@
 		792572411DF23BDA006A1526 /* LocalHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 792572401DF23BDA006A1526 /* LocalHelper.swift */; };
 		792572421DF23BDA006A1526 /* LocalHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 792572401DF23BDA006A1526 /* LocalHelper.swift */; };
 		792572431DF23BDA006A1526 /* LocalHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 792572401DF23BDA006A1526 /* LocalHelper.swift */; };
+		7936BC121E880F5700A6C81C /* FTPFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7936BC111E880F5700A6C81C /* FTPFileProvider.swift */; };
+		7936BC131E880F5700A6C81C /* FTPFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7936BC111E880F5700A6C81C /* FTPFileProvider.swift */; };
+		7936BC141E880F5700A6C81C /* FTPFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7936BC111E880F5700A6C81C /* FTPFileProvider.swift */; };
 		79480FF61E3ABDD0007E7275 /* CloudFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79480FF51E3ABDD0007E7275 /* CloudFileProvider.swift */; };
 		79480FF71E3ABDD0007E7275 /* CloudFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79480FF51E3ABDD0007E7275 /* CloudFileProvider.swift */; };
 		79480FF81E3ABDD0007E7275 /* CloudFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79480FF51E3ABDD0007E7275 /* CloudFileProvider.swift */; };
@@ -47,6 +50,10 @@
 		794C220E1D591A4B00EC49B8 /* SMB2QueryTypes.swift in Sources */ = {isa = PBXBuildFile; fileRef = 794C220D1D591A4B00EC49B8 /* SMB2QueryTypes.swift */; };
 		794C220F1D591A4B00EC49B8 /* SMB2QueryTypes.swift in Sources */ = {isa = PBXBuildFile; fileRef = 794C220D1D591A4B00EC49B8 /* SMB2QueryTypes.swift */; };
 		794C22101D591A4B00EC49B8 /* SMB2QueryTypes.swift in Sources */ = {isa = PBXBuildFile; fileRef = 794C220D1D591A4B00EC49B8 /* SMB2QueryTypes.swift */; };
+		796807551E7BF17E00BBB87B /* FileProviderExtensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 796807541E7BF17E00BBB87B /* FileProviderExtensions.swift */; };
+		796807561E7BF17E00BBB87B /* FileProviderExtensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 796807541E7BF17E00BBB87B /* FileProviderExtensions.swift */; };
+		796807571E7BF17E00BBB87B /* FileProviderExtensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 796807541E7BF17E00BBB87B /* FileProviderExtensions.swift */; };
+		798654331E8874BC002FA550 /* FTPHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 798654321E8874BC002FA550 /* FTPHelper.swift */; };
 		799396AA1D48C02300086753 /* DropboxFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 799396931D48C02300086753 /* DropboxFileProvider.swift */; };
 		799396AB1D48C02300086753 /* DropboxFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 799396931D48C02300086753 /* DropboxFileProvider.swift */; };
 		799396AC1D48C02300086753 /* DropboxFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 799396931D48C02300086753 /* DropboxFileProvider.swift */; };
@@ -109,12 +116,14 @@
 		79BD63BE1E2CC3C20035128C /* ImageIO.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 79BD63BD1E2CC3C20035128C /* ImageIO.framework */; };
 		79BD63C01E2CC3CD0035128C /* CoreGraphics.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 79BD63BF1E2CC3CD0035128C /* CoreGraphics.framework */; };
 		79BD63C21E2CC3D30035128C /* AVFoundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 79BD63C11E2CC3D30035128C /* AVFoundation.framework */; };
-		79BD63C51E2D17880035128C /* OneDriveFileProvide.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79BD63C31E2D17880035128C /* OneDriveFileProvide.swift */; };
-		79BD63C61E2D17880035128C /* OneDriveFileProvide.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79BD63C31E2D17880035128C /* OneDriveFileProvide.swift */; };
-		79BD63C71E2D17880035128C /* OneDriveFileProvide.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79BD63C31E2D17880035128C /* OneDriveFileProvide.swift */; };
+		79BD63C51E2D17880035128C /* OneDriveFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79BD63C31E2D17880035128C /* OneDriveFileProvider.swift */; };
+		79BD63C61E2D17880035128C /* OneDriveFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79BD63C31E2D17880035128C /* OneDriveFileProvider.swift */; };
+		79BD63C71E2D17880035128C /* OneDriveFileProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79BD63C31E2D17880035128C /* OneDriveFileProvider.swift */; };
 		79BD63C81E2D17880035128C /* OneDriveHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79BD63C41E2D17880035128C /* OneDriveHelper.swift */; };
 		79BD63C91E2D17880035128C /* OneDriveHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79BD63C41E2D17880035128C /* OneDriveHelper.swift */; };
 		79BD63CA1E2D17880035128C /* OneDriveHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79BD63C41E2D17880035128C /* OneDriveHelper.swift */; };
+		79F4678B1E8B80F200C91A85 /* FTPHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 798654321E8874BC002FA550 /* FTPHelper.swift */; };
+		79F4678C1E8B80F200C91A85 /* FTPHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 798654321E8874BC002FA550 /* FTPHelper.swift */; };
 		79F5745B1DFDB10B00179ABF /* FileObject.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79F5745A1DFDB10A00179ABF /* FileObject.swift */; };
 		79F5745C1DFDB10B00179ABF /* FileObject.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79F5745A1DFDB10A00179ABF /* FileObject.swift */; };
 		79F5745D1DFDB10B00179ABF /* FileObject.swift in Sources */ = {isa = PBXBuildFile; fileRef = 79F5745A1DFDB10A00179ABF /* FileObject.swift */; };
@@ -130,10 +139,13 @@
 		7924B1921D89DAE000589DB7 /* Parser.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Parser.swift; sourceTree = "<group>"; };
 		7924B1A81D89F79200589DB7 /* FPSStreamTask.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FPSStreamTask.swift; sourceTree = "<group>"; };
 		792572401DF23BDA006A1526 /* LocalHelper.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = LocalHelper.swift; sourceTree = "<group>"; };
+		7936BC111E880F5700A6C81C /* FTPFileProvider.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FTPFileProvider.swift; sourceTree = "<group>"; };
 		79480FF51E3ABDD0007E7275 /* CloudFileProvider.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = CloudFileProvider.swift; sourceTree = "<group>"; };
 		794C21FD1D58912A00EC49B8 /* DropboxHelper.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DropboxHelper.swift; sourceTree = "<group>"; };
 		794C22091D5893F800EC49B8 /* SMB2Notification.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SMB2Notification.swift; sourceTree = "<group>"; };
 		794C220D1D591A4B00EC49B8 /* SMB2QueryTypes.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SMB2QueryTypes.swift; sourceTree = "<group>"; };
+		796807541E7BF17E00BBB87B /* FileProviderExtensions.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FileProviderExtensions.swift; sourceTree = "<group>"; };
+		798654321E8874BC002FA550 /* FTPHelper.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FTPHelper.swift; sourceTree = "<group>"; };
 		799396671D48B7F600086753 /* FileProvider.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = FileProvider.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		799396751D48B80D00086753 /* FileProvider.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = FileProvider.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		799396821D48B82700086753 /* FileProvider.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = FileProvider.framework; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -162,18 +174,15 @@
 		79BD63A71E2CC2940035128C /* CoreGraphics.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = CoreGraphics.framework; path = Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS10.2.sdk/System/Library/Frameworks/CoreGraphics.framework; sourceTree = DEVELOPER_DIR; };
 		79BD63A91E2CC2BB0035128C /* AVFoundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = AVFoundation.framework; path = Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS10.2.sdk/System/Library/Frameworks/AVFoundation.framework; sourceTree = DEVELOPER_DIR; };
 		79BD63AB1E2CC2C20035128C /* ImageIO.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = ImageIO.framework; path = Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS10.2.sdk/System/Library/Frameworks/ImageIO.framework; sourceTree = DEVELOPER_DIR; };
-		79BD63AD1E2CC2EB0035128C /* MediaPlayer.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = MediaPlayer.framework; path = Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS10.2.sdk/System/Library/Frameworks/MediaPlayer.framework; sourceTree = DEVELOPER_DIR; };
 		79BD63AF1E2CC3300035128C /* libxml2.tbd */ = {isa = PBXFileReference; lastKnownFileType = "sourcecode.text-based-dylib-definition"; name = libxml2.tbd; path = usr/lib/libxml2.tbd; sourceTree = SDKROOT; };
 		79BD63B11E2CC3350035128C /* ImageIO.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = ImageIO.framework; path = System/Library/Frameworks/ImageIO.framework; sourceTree = SDKROOT; };
-		79BD63B31E2CC33D0035128C /* MediaPlayer.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = MediaPlayer.framework; path = System/Library/Frameworks/MediaPlayer.framework; sourceTree = SDKROOT; };
 		79BD63B51E2CC3860035128C /* CoreFoundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = CoreFoundation.framework; path = System/Library/Frameworks/CoreFoundation.framework; sourceTree = SDKROOT; };
 		79BD63B71E2CC38D0035128C /* AVFoundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = AVFoundation.framework; path = System/Library/Frameworks/AVFoundation.framework; sourceTree = SDKROOT; };
 		79BD63B91E2CC39B0035128C /* libxml2.tbd */ = {isa = PBXFileReference; lastKnownFileType = "sourcecode.text-based-dylib-definition"; name = libxml2.tbd; path = Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS10.1.sdk/usr/lib/libxml2.tbd; sourceTree = DEVELOPER_DIR; };
-		79BD63BB1E2CC3B90035128C /* MediaPlayer.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = MediaPlayer.framework; path = Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS10.1.sdk/System/Library/Frameworks/MediaPlayer.framework; sourceTree = DEVELOPER_DIR; };
 		79BD63BD1E2CC3C20035128C /* ImageIO.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = ImageIO.framework; path = Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS10.1.sdk/System/Library/Frameworks/ImageIO.framework; sourceTree = DEVELOPER_DIR; };
 		79BD63BF1E2CC3CD0035128C /* CoreGraphics.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = CoreGraphics.framework; path = Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS10.1.sdk/System/Library/Frameworks/CoreGraphics.framework; sourceTree = DEVELOPER_DIR; };
 		79BD63C11E2CC3D30035128C /* AVFoundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = AVFoundation.framework; path = Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS10.1.sdk/System/Library/Frameworks/AVFoundation.framework; sourceTree = DEVELOPER_DIR; };
-		79BD63C31E2D17880035128C /* OneDriveFileProvide.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = OneDriveFileProvide.swift; sourceTree = "<group>"; };
+		79BD63C31E2D17880035128C /* OneDriveFileProvider.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = OneDriveFileProvider.swift; sourceTree = "<group>"; };
 		79BD63C41E2D17880035128C /* OneDriveHelper.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = OneDriveHelper.swift; sourceTree = "<group>"; };
 		79F5745A1DFDB10A00179ABF /* FileObject.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FileObject.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
@@ -221,14 +230,11 @@
 				79BD63C11E2CC3D30035128C /* AVFoundation.framework */,
 				79BD63BF1E2CC3CD0035128C /* CoreGraphics.framework */,
 				79BD63BD1E2CC3C20035128C /* ImageIO.framework */,
-				79BD63BB1E2CC3B90035128C /* MediaPlayer.framework */,
 				79BD63B91E2CC39B0035128C /* libxml2.tbd */,
 				79BD63B71E2CC38D0035128C /* AVFoundation.framework */,
 				79BD63B51E2CC3860035128C /* CoreFoundation.framework */,
-				79BD63B31E2CC33D0035128C /* MediaPlayer.framework */,
 				79BD63B11E2CC3350035128C /* ImageIO.framework */,
 				79BD63AF1E2CC3300035128C /* libxml2.tbd */,
-				79BD63AD1E2CC2EB0035128C /* MediaPlayer.framework */,
 				79BD63AB1E2CC2C20035128C /* ImageIO.framework */,
 				79BD63A91E2CC2BB0035128C /* AVFoundation.framework */,
 				79BD63A71E2CC2940035128C /* CoreGraphics.framework */,
@@ -287,6 +293,7 @@
 				799396991D48C02300086753 /* SMBTypes */,
 				799396941D48C02300086753 /* FileProvider.h */,
 				799396951D48C02300086753 /* FileProvider.swift */,
+				796807541E7BF17E00BBB87B /* FileProviderExtensions.swift */,
 				79F5745A1DFDB10A00179ABF /* FileObject.swift */,
 				799396961D48C02300086753 /* LocalFileProvider.swift */,
 				792572401DF23BDA006A1526 /* LocalHelper.swift */,
@@ -295,7 +302,9 @@
 				7902C0851D61B56D00564440 /* RemoteSession.swift */,
 				799396931D48C02300086753 /* DropboxFileProvider.swift */,
 				794C21FD1D58912A00EC49B8 /* DropboxHelper.swift */,
-				79BD63C31E2D17880035128C /* OneDriveFileProvide.swift */,
+				7936BC111E880F5700A6C81C /* FTPFileProvider.swift */,
+				798654321E8874BC002FA550 /* FTPHelper.swift */,
+				79BD63C31E2D17880035128C /* OneDriveFileProvider.swift */,
 				79BD63C41E2D17880035128C /* OneDriveHelper.swift */,
 				7924B1A81D89F79200589DB7 /* FPSStreamTask.swift */,
 				799396971D48C02300086753 /* SMBClient.swift */,
@@ -481,16 +490,19 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				796807551E7BF17E00BBB87B /* FileProviderExtensions.swift in Sources */,
 				799396B31D48C02300086753 /* LocalFileProvider.swift in Sources */,
 				799396D41D48C02300086753 /* SMB2Tree.swift in Sources */,
 				7924B1A21D89DAE000589DB7 /* Options.swift in Sources */,
 				792572411DF23BDA006A1526 /* LocalHelper.swift in Sources */,
+				7936BC121E880F5700A6C81C /* FTPFileProvider.swift in Sources */,
 				79480FF61E3ABDD0007E7275 /* CloudFileProvider.swift in Sources */,
 				79F5745B1DFDB10B00179ABF /* FileObject.swift in Sources */,
-				79BD63C51E2D17880035128C /* OneDriveFileProvide.swift in Sources */,
+				79BD63C51E2D17880035128C /* OneDriveFileProvider.swift in Sources */,
 				7924B1991D89DAE000589DB7 /* Element.swift in Sources */,
 				799396C81D48C02300086753 /* SMB2IOCtl.swift in Sources */,
 				799396D71D48C02300086753 /* SMB2Types.swift in Sources */,
+				798654331E8874BC002FA550 /* FTPHelper.swift in Sources */,
 				7924B1B21D89FCDA00589DB7 /* FPSStreamTask.swift in Sources */,
 				799396C51D48C02300086753 /* SMB2FileOperation.swift in Sources */,
 				79BD63C81E2D17880035128C /* OneDriveHelper.swift in Sources */,
@@ -521,16 +533,19 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				796807561E7BF17E00BBB87B /* FileProviderExtensions.swift in Sources */,
 				799396B41D48C02300086753 /* LocalFileProvider.swift in Sources */,
 				799396D51D48C02300086753 /* SMB2Tree.swift in Sources */,
 				7924B1A31D89DAE000589DB7 /* Options.swift in Sources */,
 				792572421DF23BDA006A1526 /* LocalHelper.swift in Sources */,
+				7936BC131E880F5700A6C81C /* FTPFileProvider.swift in Sources */,
 				79480FF71E3ABDD0007E7275 /* CloudFileProvider.swift in Sources */,
 				79F5745C1DFDB10B00179ABF /* FileObject.swift in Sources */,
-				79BD63C61E2D17880035128C /* OneDriveFileProvide.swift in Sources */,
+				79BD63C61E2D17880035128C /* OneDriveFileProvider.swift in Sources */,
 				7924B1B01D89F7DE00589DB7 /* FPSStreamTask.swift in Sources */,
 				7924B19A1D89DAE000589DB7 /* Element.swift in Sources */,
 				799396C91D48C02300086753 /* SMB2IOCtl.swift in Sources */,
+				79F4678B1E8B80F200C91A85 /* FTPHelper.swift in Sources */,
 				799396D81D48C02300086753 /* SMB2Types.swift in Sources */,
 				799396C61D48C02300086753 /* SMB2FileOperation.swift in Sources */,
 				79BD63C91E2D17880035128C /* OneDriveHelper.swift in Sources */,
@@ -561,16 +576,19 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				796807571E7BF17E00BBB87B /* FileProviderExtensions.swift in Sources */,
 				799396B51D48C02300086753 /* LocalFileProvider.swift in Sources */,
 				799396D61D48C02300086753 /* SMB2Tree.swift in Sources */,
 				7924B1A41D89DAE000589DB7 /* Options.swift in Sources */,
 				792572431DF23BDA006A1526 /* LocalHelper.swift in Sources */,
+				7936BC141E880F5700A6C81C /* FTPFileProvider.swift in Sources */,
 				79480FF81E3ABDD0007E7275 /* CloudFileProvider.swift in Sources */,
 				79F5745D1DFDB10B00179ABF /* FileObject.swift in Sources */,
-				79BD63C71E2D17880035128C /* OneDriveFileProvide.swift in Sources */,
+				79BD63C71E2D17880035128C /* OneDriveFileProvider.swift in Sources */,
 				7924B1B11D89F7DF00589DB7 /* FPSStreamTask.swift in Sources */,
 				7924B19B1D89DAE000589DB7 /* Element.swift in Sources */,
 				799396CA1D48C02300086753 /* SMB2IOCtl.swift in Sources */,
+				79F4678C1E8B80F200C91A85 /* FTPHelper.swift in Sources */,
 				799396D91D48C02300086753 /* SMB2Types.swift in Sources */,
 				799396C71D48C02300086753 /* SMB2FileOperation.swift in Sources */,
 				79BD63CA1E2D17880035128C /* OneDriveHelper.swift in Sources */,
@@ -603,7 +621,7 @@
 		799396601D48B7BF00086753 /* Debug */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
-				BUNDLE_VERSION_STRING = 0.11.4;
+				BUNDLE_VERSION_STRING = 0.15.5;
 				CLANG_WARN_BOOL_CONVERSION = YES;
 				CLANG_WARN_CONSTANT_CONVERSION = YES;
 				CLANG_WARN_EMPTY_BODY = YES;
@@ -613,6 +631,7 @@
 				CLANG_WARN_SUSPICIOUS_MOVE = YES;
 				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
+				COPY_PHASE_STRIP = NO;
 				DEBUG_INFORMATION_FORMAT = dwarf;
 				ENABLE_BITCODE = YES;
 				ENABLE_STRICT_OBJC_MSGSEND = YES;
@@ -633,7 +652,7 @@
 		799396611D48B7BF00086753 /* Release */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
-				BUNDLE_VERSION_STRING = 0.11.4;
+				BUNDLE_VERSION_STRING = 0.15.5;
 				CLANG_WARN_BOOL_CONVERSION = YES;
 				CLANG_WARN_CONSTANT_CONVERSION = YES;
 				CLANG_WARN_EMPTY_BODY = YES;
@@ -663,7 +682,6 @@
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
 				APPLICATION_EXTENSION_API_ONLY = YES;
-				BUNDLE_VERSION_STRING = 0.8.2;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_ARC = YES;
@@ -716,7 +734,6 @@
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
 				APPLICATION_EXTENSION_API_ONLY = YES;
-				BUNDLE_VERSION_STRING = 0.8.2;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_ARC = YES;
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0810"
+   LastUpgradeVersion = "0820"
   version = "1.3">
   <BuildAction
      parallelizeBuildables = "YES"
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0810"
+   LastUpgradeVersion = "0820"
   version = "1.3">
   <BuildAction
      parallelizeBuildables = "YES"
@@ -1,6 +1,6 @@
 The MIT License (MIT)

-Copyright (c) 2016 Amir Abbas Mousavian
+Copyright (c) 2016-17 Amir Abbas Mousavian

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -1,51 +1,53 @@
-# FileProvider
+![File Provider](fileprovider.png)

 >This Swift library provide a swifty way to deal with local and remote files and directories in a unified way.

 [![Swift Version][swift-image]][swift-url]
-[![Platform](https://img.shields.io/badge/Platform-iOS%2C%20macOS%2C%20tvOS-lightgray.svg)](#)
+[![Platform][platform-image]](#)
 [![License][license-image]][license-url]

-[![release badge][release-image]][release-url]
-[![CocoaPods Compatible](https://img.shields.io/cocoapods/v/FileProvider.svg)](https://cocoapods.org/pods/FileProvider)
-[![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?)](https://github.com/Carthage/Carthage)
+[![Release versin][release-image]][release-url]
+[![CocoaPods version](https://img.shields.io/cocoapods/v/FileProvider.svg)][cocoapods]
+[![Carthage compatible][carthage-image]](https://github.com/Carthage/Carthage)

 [![Build Status][travis-image]][travis-url]
-[![codebeat badge][codebeat-image]][codebeat-url]
+[![Codebeat Badge][codebeat-image]][codebeat-url]
+[![Cocoapods Docs][docs-image]][docs-url]
+[![Cocoapods Downloads][cocoapods-downloads]][cocoapods]
+[![Cocoapods Apps][cocoapods-apps]][cocoapods]

 <!--- 
 [![codecov](https://codecov.io/gh/amosavian/FileProvider/branch/master/graph/badge.svg)](https://codecov.io/gh/amosavian/FileProvider) 
 ---> 

-This library provides implementaion of WebDav, Dropbox, OneDrive and SMB2 (incomplete) and local files.
+This library provides implementaion of WebDav, FTP, Dropbox, OneDrive and SMB2 (incomplete) and local files.

-All functions are async calls and it wont block your main thread.
-
-Local and WebDAV providers are fully tested and can be used in production environment.
+All functions do async calls and it wont block your main thread.

 ## Features

- [x] **LocalFileProvider** a wrapper around `FileManager` with some additions like searching and reading a portion of file.
- [x] **WebDAVFileProvider** WebDAV protocol is defacto file transmission standard, replaced FTP.
+- [x] **LocalFileProvider** a wrapper around `FileManager` with some additions like builtin coordinating, searching and reading a portion of file.
+- [x] **CloudFileProvider** A wrapper around app's ubiquitous container API of iCloud Drive.
+- [x] **WebDAVFileProvider** WebDAV protocol is defacto file transmission standard, supported by some cloud services like `ownCloud`, `Box.com` and `Yandex.disk`.
+- [x] **FTPFileProvider** While deprecated in 1990s due to serious security concerns, it's still in use on some Web hosts.
+    * Active mode is not implemented yet.
 - [x] **DropboxFileProvider** A wrapper around Dropbox Web API.
-* For now it has limitation in uploading files up to 150MB.
- [x] **OneDriveFileProvider** A wrapper around OneDrive Web API, works with `onedrive.com` and compatible (business) servers.
-* For now it has limitation in uploading files up to 100MB.
- [x] **CloudFileProvider** A wrapper around app's ubiquitous container to iCloud Drive in iOS 8+ API.
- [ ] **SMBFileProvider** SMB2/3 introduced in 2006, which is a file and printer sharing protocol originated from Microsoft Windows and now is replacing AFP protocol on MacOS.
-* Data types and some basic functions are implemented but *main interface is not implemented yet!*
-*  SMB1/CIFS is depericated and very tricky to be implemented
- [ ] **FTPFileProvider** while deprecated in 1990s, it's still in use on some Web hosts.
- [ ] **AmazonS3FileProvider** 
- [ ] **GoogleDriveFileProvider**
+    * For now it has limitation in uploading files up to 150MB.
+- [x] **OneDriveFileProvider** A wrapper around OneDrive REST API, works with `onedrive.com` and compatible (business) servers.
+    * For now it has limitation in uploading files up to 100MB.
+- [ ] **GoogleFileProvider** A wrapper around Goodle Drive REST API.
+- [ ] **AmazonS3FileProvider** Amazon storage backend. Used by many sites.
+- [ ] **SMBFileProvider** SMB2/3 introduced in 2006, which is a file and printer sharing protocol originated from Microsoft Windows and now is replacing AFP protocol on macOS.
+    * Data types and some basic functions are implemented but *main interface is not implemented yet!*.
+    * SMB1/CIFS is deprecated and very tricky to be implemented due to strict memory allignment in Swift.

 ## Requirements

- **Swift 3**
+- **Swift 3.0 or higher**
 - iOS 8.0 , OSX 10.10
 - XCode 8.0

-Legacy version is available in swift-2 branch
+Legacy version is available in swift-2 branch.

 ## Installation

@@ -66,7 +68,7 @@ github "amosavian/FileProvider"
 Or to use in Swift Package Manager add this line in `Dependencies`:

 ```swift
-.Package(url: "https://github.com/amosavian/FileProvider.git", majorVersion: 0, minorVersion: 8)
+.Package(url: "https://github.com/amosavian/FileProvider.git", majorVersion: 0)
 ```

 ### Manually
@@ -92,7 +94,7 @@ Then you can do either:

 * Copy Source folder to your project and Voila!

-* Drop FileProvider.xcodeproj to you Xcode workspace and add the framework to your Embeded Binaries in target.
+* Drop `FileProvider.xcodeproj` to you Xcode workspace and add the framework to your Embeded Binaries in target.

 ## Usage

@@ -106,7 +108,7 @@ For LocalFileProvider if you want to deal with `Documents` folder
 let documentsProvider = LocalFileProvider()

 // Equals with:
-let documentsProvider = LocalFileProvider(directory: .documentDirectory, domainMask: = .userDomainMask)
+let documentsProvider = LocalFileProvider(for: .documentDirectory, in: .userDomainMask)

 // Equals with:
 let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
@@ -117,12 +119,12 @@ Also for using group shared container:

 ```swift
 let documentsProvider = LocalFileProvider(sharedContainerId: "group.yourcompany.appContainer")
-// Replace your group identifier with string above
+// Replace your group identifier
 ```

 You can't change the base url later. and all paths are related to this base url by default.

-To initialize an iCloud Container provider use below code, This will automatically manager creating Documents folder in container:
+To initialize an iCloud Container provider look at [here](https://medium.com/ios-os-x-development/icloud-drive-documents-1a46b5706fe1) to see how to update project settings then use below code, This will automatically manager creating Documents folder in container:

 ```swift
 let documentsProvider = CloudFileProvider(containerId: nil)
@@ -142,13 +144,13 @@ let webdavProvider = WebDAVFileProvider(baseURL: URL(string: "http://www.example
 	
 For interaction with UI, set delegate variable of `FileProvider` object

-You can use `absoluteURL()` method if provider to get direct access url (local or remote files) for some file systems which allows to do so (Dropbox doesn't support and returns path simply wrapped in URL)
+You can use `url(of:)` method if provider to get direct access url (local or remote files) for some file systems which allows to do so (Dropbox doesn't support and returns path simply wrapped in URL)

 ### Delegates

 For updating User interface please consider using delegate method instead of completion handlers. Delegate methods are guaranteed to run in main thread to avoid bugs.

-It's simply three method which indicated whether the operation failed, succeed and how much of operation has been done (suitable for uploading and downloading operations).
+There's simply three method which indicated whether the operation failed, succeed and how much of operation has been done (suitable for uploading and downloading operations).

 Your class should conforms `FileProviderDelegate` class:

@@ -157,7 +159,7 @@ override func viewDidLoad() {
 	documentsProvider.delegate = self as FileProviderDelegate
 }
 	
-func fileproviderSucceed(_ fileProvider: FileProviderOperations, operation: FileOperation) {
+func fileproviderSucceed(_ fileProvider: FileProviderOperations, operation: FileOperationType) {
 	switch operation {
 	case .copy(source: let source, destination: let dest):
 		print("\(source) copied to \(dest).")
@@ -168,7 +170,7 @@ func fileproviderSucceed(_ fileProvider: FileProviderOperations, operation: File
 	}
 }

-func fileproviderFailed(_ fileProvider: FileProviderOperations, operation: FileOperation) {
+func fileproviderFailed(_ fileProvider: FileProviderOperations, operation: FileOperationType) {
    switch operation {
 	case .copy(source: let source, destination: let dest):
 		print("copy of \(source) failed.")
@@ -179,7 +181,7 @@ func fileproviderFailed(_ fileProvider: FileProviderOperations, operation: FileO
 	}
 }
 	
-func fileproviderProgress(_ fileProvider: FileProviderOperations, operation: FileOperation, progress: Float) {
+func fileproviderProgress(_ fileProvider: FileProviderOperations, operation: FileOperationType, progress: Float) {
 	switch operation {
 	case .copy(source: let source, destination: let dest):
 		print("Copy\(source) to \(dest): \(progress * 100) completed.")
@@ -201,7 +203,7 @@ You can also implement `FileOperationDelegate` protocol to control behaviour of

 `fileProvider(shouldProceedAfterError:, operation:)` will be called if an error occured during file operations. Return `true` if you want to continue operation on next files or `false` if you want stop operation further. Default value is false if you don't implement delegate.

-**Note: these methods will be called for files in a directory and its subfolders recursively.**
+**Note: In `LocalFileProvider`, these methods will be called for files in a directory and its subfolders recursively.**

 ### Directory contents and file attributes

@@ -261,15 +263,16 @@ You can then pass "" (empty string) to `contentsOfDirectory` method to list file
 Creating new directory:

 ```swift
-documentsProvider.create(folder: "new folder", at: "/", completionHandler: nil)
+documentsProvider.create(folder: "new folder", at: "/", completionHandler: { error in
+    if let error = error {
+        // Error handling here
+    } else {
+        // The operation succeed
+    }
+})
 ```

-Creating new file from data:
-
-```swift
-let data = "hello world!".data(encoding: .utf8)
-documentsProvider.create(file: "newFile.txt", at: "/", contents: data, completionHandler: nil)
-```
+To create a file, use `writeContents(path:, content:, atomically:, completionHandler:)` method.

 ### Copy and Move/Rename Files

@@ -293,11 +296,11 @@ documentsProvider.moveItem(path: "new folder/old.txt", to: "new.txt", overwrite:
 documentsProvider.removeItem(path: "new.txt", completionHandler: nil)
 ```

-***Caution:*** This method will delete directories with all it's contents recursively.
+***Caution:*** This method will delete directories with all it's contents recursively except for FTP providers that don't support `SITE RMDIR` command, this will be fixed later.

 ### Fetching Contents of File

-There is two method for this purpose, one of them loads entire file into NSData and another can load a portion of file.
+There is two method for this purpose, one of them loads entire file into `Data` and another can load a portion of file.

 ```swift
 documentsProvider.contents(path: "old.txt", completionHandler: {
@@ -326,20 +329,87 @@ let data = "What's up Newyork!".data(encoding: .utf8)
 documentsProvider.writeContents(path: "old.txt", content: data, atomically: true, completionHandler: nil)
 ```

+### Copying Files to and From Local URL
+
+There are two methods to download and upload files between provider's and local storage. These methods use `URLSessionDownloadTask` and `URLSessionUploadTask` classes and allows to use background session and provide progress via delegate.
+
+To upload a file:
+
+```swift
+let fileURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("image.jpg")
+documentsProvider.copyItem(localFile: fileURL, to: "/upload/image.jpg", overwrite: true, completionHandler: nil)
+```
+
+To download a file:
+
+```swift
+let fileURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("image.jpg")
+documentsProvider.copyItem(path: "/download/image.jpg", toLocalURL: fileURL, overwrite: true, completionHandler: nil)
+```
+
+* It's safe only to assume these methods **won't** handle directories to upload/download recursively. If you need, you can list directories, create directories on target and copy files using these methods.
+* FTP provider allows developer to either use apple implemented `URLSessionDownloadTask` or custom implemented method based on stream task via `useAppleImplementation` property. FTP protocol is not supported by background session.
+
+### Undo Operations
+
+Providers conform to `FileProviderUndoable` can perform undo for **some** operations like moving/renaming, copying and creating (file or folder). **Now, only `LocalFileProvider` supports this feature.** To implement:
+
+```swift
+// To setup a new UndoManager:
+documentsProvider.setupUndoManager()
+// or if you have an UndoManager object already:
+documentsProvider.undoManager = self.undoManager
+
+// e.g.: To undo last operation manually:
+documentsProvider.undoManager?.undo()
+``` 
+
+You can also bind `UndoManager` object with view controller to use shake gesture and builtin undo support in iOS/macOS, add these code to your ViewController class like this sample code:
+
+```swift
+class ViewController: UIViewController
+    override var canBecomeFirstResponder: Bool {
+        return true
+    }
+    
+    override var undoManager: UndoManager? {
+        return (provider as? FileProvideUndoable)?.undoManager
+    }
+    
+    override func viewDidAppear(_ animated: Bool) {
+        super.viewDidAppear(animated)
+        // Your code here
+        UIApplication.shared.applicationSupportsShakeToEdit = true
+        self.becomeFirstResponder()
+    }
+    
+    override func viewWillDisappear(_ animated: Bool) {
+        super.viewWillDisappear(animated)
+        // Your code here
+        UIApplication.shared.applicationSupportsShakeToEdit = false
+        self.resignFirstResponder()
+    }
+    // The rest of your implementation
+}
+```
+
 ### Operation Handle

 Creating/Copying/Deleting functions return a `OperationHandle` for remote operations. It provides operation type, progress and a `.cancel()` method which allows you to cancel operation in midst.

 It's not supported by native `(NS)FileManager` so `LocalFileProvider`, but this functionality will be added to future `PosixFileProvider` class.

-### Monitoring FIle Changes
+### File Coordination
+
+`LocalFileProvider` and its descendents has a `isCoordinating` property. By setting this, provider will use `NSFileCoordinating` class to do all file operations. It's mandatory for iCloud, while recommended when using shared container or anywhere that simultaneous operations on a file/folder is common.
+
+### Monitoring File Changes

 You can monitor updates in some file system (Local and SMB2), there is three methods in supporting provider you can use to register a handler, to unregister and to check whether it's being monitored or not. It's useful to find out when new files added or removed from directory and update user interface. The handler will be dispatched to main threads to avoid UI bugs with a 0.25 sec delay.

 ```swift
 // to register a new notification handler
-documentsProvider.registerNotifcation(path: provider.currentPath)
-{
+documentsProvider.registerNotifcation(path: provider.currentPath) {
 	// calling functions to update UI 
 }
 	
@@ -362,7 +432,7 @@ To check either file thumbnail is supported or not and fetch thumbnail, use (and
 let path = "/newImage.jpg"
 let thumbSize = CGSize(width: 64, height: 64)
 if documentsProvider.thumbnailOfFileSupported(path: path {
-    documentsProvider..thumbnailOfFile(path: file.path, dimension: thumbSize, completionHandler: { (image, error) in
+    documentsProvider.thumbnailOfFile(path: file.path, dimension: thumbSize, completionHandler: { (image, error) in
        DispatchQueue.main.async {
            self.previewImage.image = image
        }
@@ -374,7 +444,7 @@ if documentsProvider.thumbnailOfFileSupported(path: path {

 ##### Meta-informations

-To get meta-information like image/video taken date, dimension, etc., use (and modify) these example code:
+To get meta-information like image/video taken date, location, dimension, etc., use (and modify) these example code:

 ```swift
 if documentsProvider..propertiesOfFile(path: file.path, completionHandler: { (propertiesDictionary, keys, error) in
@@ -390,6 +460,13 @@ if documentsProvider..propertiesOfFile(path: file.path, completionHandler: { (pr

 We would love for you to contribute to **FileProvider**, check the `LICENSE` file for more info.

+Things you may consider to help us:
+
+- [ ] Implement request/response stack for `SMBClient`
+- [ ] Implement Test-case (`XCTest`)
+- [ ] Add Sample project for iOS
+- [ ] Add Sample project for macOS
+
 ## Projects in use

 * [EDM - Browse and Receive Files](https://itunes.apple.com/us/app/edm-browse-and-receive-files/id948397575?ls=1&mt=8)
@@ -399,19 +476,28 @@ If you used this library in your project, you can open an issue to inform us.

 ## Meta

-Amir-Abbas Mousavian  – [@amosavian](https://twitter.com/amosavian)
+Amir-Abbas Mousavian – [@amosavian](https://twitter.com/amosavian)
+
+Thanks to [Hootan Moradi](https://github.com/hoootan) for designing logo.

 Distributed under the MIT license. See `LICENSE` for more information.

 [https://github.com/amosavian/](https://github.com/amosavian/)

-[swift-image]:https://img.shields.io/badge/swift-3.0-orange.svg
+[cocoapods]: https://cocoapods.org/pods/FileProvider
+[swift-image]: https://img.shields.io/badge/swift-3.0,%203.1-orange.svg
 [swift-url]: https://swift.org/
-[license-image]: https://img.shields.io/badge/License-MIT-blue.svg
+[platform-image]: https://img.shields.io/cocoapods/p/FileProvider.svg
+[license-image]: https://img.shields.io/github/license/amosavian/FileProvider.svg
 [license-url]: LICENSE
 [codebeat-image]: https://codebeat.co/badges/7b359f48-78eb-4647-ab22-56262a827517
 [codebeat-url]: https://codebeat.co/projects/github-com-amosavian-fileprovider
 [travis-image]: https://img.shields.io/travis/amosavian/FileProvider/master.svg
 [travis-url]: https://travis-ci.org/amosavian/FileProvider
 [release-url]: https://github.com/amosavian/FileProvider/releases
-[release-image]: https://img.shields.io/github/release/amosavian/FileProvider.svg
+[release-image]: https://img.shields.io/github/release/amosavian/FileProvider.svg
+[carthage-image]: https://img.shields.io/badge/Carthage-compatible-4BC51D.svg
+[cocoapods-downloads]: https://img.shields.io/cocoapods/dt/FileProvider.svg
+[cocoapods-apps]: https://img.shields.io/cocoapods/at/FileProvider.svg
+[docs-image]: https://img.shields.io/cocoapods/metrics/doc-percent/FileProvider.svg
+[docs-url]: http://cocoadocs.org/docsets/FileProvider/
@@ -1,29 +0,0 @@
-//
-// AEXML.h
-//
-// Copyright (c) 2014 Marko Tadić <tadija@me.com> http://tadija.net
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included in all
-// copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-// SOFTWARE.
-//
-
-#import <Foundation/Foundation.h>
-
-FOUNDATION_EXPORT double AEXMLVersionNumber;
-FOUNDATION_EXPORT const unsigned char AEXMLVersionString[];
-
@@ -29,7 +29,7 @@ import Foundation

    XML Parsing is also done with this object.
 */
-open class AEXMLDocument: AEXMLElement {
+internal class AEXMLDocument: AEXMLElement {
    
    // MARK: - Properties
    
@@ -30,7 +30,7 @@ import Foundation
    You can access its structure by using subscript like this: `element["foo"]["bar"]` which would
    return `<bar></bar>` element from `<element><foo><bar></bar></foo></element>` XML as an `AEXMLElement` object.
 */
-open class AEXMLElement {
+internal class AEXMLElement {
    
    // MARK: - Properties
    
@@ -86,7 +86,7 @@ open class AEXMLElement {
    /// The first element with given name **(Empty element with error if not exists)**.
    open subscript(key: String) -> AEXMLElement {
        guard let
-            first = children.filter({ $0.name == key }).first
+            first = children.first(where: { $0.name == key })
        else {
            let errorElement = AEXMLElement(name: key)
            errorElement.error = AEXMLError.elementNotFound
@@ -25,7 +25,7 @@
 import Foundation

 /// A type representing error value that can be thrown or inside `error` property of `AEXMLElement`.
-public enum AEXMLError: Error {
+internal enum AEXMLError: Error {
    /// This will be inside `error` property of `AEXMLElement` when subscript is used for not-existing element.
    case elementNotFound
    
@@ -1,26 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
-<plist version="1.0">
-<dict>
-	<key>CFBundleDevelopmentRegion</key>
-	<string>en</string>
-	<key>CFBundleExecutable</key>
-	<string>$(EXECUTABLE_NAME)</string>
-	<key>CFBundleIdentifier</key>
-	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
-	<key>CFBundleInfoDictionaryVersion</key>
-	<string>6.0</string>
-	<key>CFBundleName</key>
-	<string>$(PRODUCT_NAME)</string>
-	<key>CFBundlePackageType</key>
-	<string>FMWK</string>
-	<key>CFBundleShortVersionString</key>
-	<string>3.0.0</string>
-	<key>CFBundleSignature</key>
-	<string>????</string>
-	<key>CFBundleVersion</key>
-	<string>$(CURRENT_PROJECT_VERSION)</string>
-	<key>NSPrincipalClass</key>
-	<string></string>
-</dict>
-</plist>
@@ -0,0 +1,19 @@
+Copyright (c) 2014-2017 Marko Tadić <tadija@me.com> http://tadija.net
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
@@ -9,7 +9,7 @@
 import Foundation

 /// Options used in `AEXMLDocument`
-public struct AEXMLOptions {
+internal struct AEXMLOptions {
    
    /// Values used in XML Document header
    public struct DocumentHeader {
@@ -8,40 +8,72 @@

 import Foundation

+/**
+ Allows accessing to iCloud Drive stored files. Determine scope when initializing, to either access
+ to public documents folder or files stored as data.
+ 
+ To setup a functional iCloud container, please
+ [read this page](https://medium.com/ios-os-x-development/icloud-drive-documents-1a46b5706fe1).
+ */
 open class CloudFileProvider: LocalFileProvider {
+    /// An string to identify type of provider.
+    open override class var type: String { return "iCloudDrive" }
    
-    public var type: String {
-        return "iCloudDrive"
-    }
-    
-    /// Actually is readonly, value is true
+    /// Forces file operations to use `NSFileCoordinating`,
+    /// Actually this is readonly, and value is always true.
    override open var isCoorinating: Bool {
        get {
            return true
        }
        set {
+            assert(true, "CloudFileProvider.isCoorinating can't be set")
            return
        }
    }
    
-    open var containerId: String?
+    /// The fully-qualified container identifier for an iCloud container directory.
+    open fileprivate(set) var containerId: String?
    
-    public init? (containerId: String?) {
-        assert(!Thread.isMainThread, "LocalFileProvider.init(containerId:) is not recommended to be executed on Main Thread.")
-        guard FileManager.default.ubiquityIdentityToken == nil else {
+    /// Scope of container, indicates user can manipulate data/files or not.
+    open fileprivate(set) var scope: UbiquitousScope
+    
+    /// Set this property to ignore initiations asserting to be on secondary thread
+    static open var asserting: Bool = true
+    
+    /**
+     Initializes the provider for the iCloud container associated with the specified identifier and 
+     establishes access to that container.
+     
+     - Important: Do not call this method from your app’s main thread. Because this method might take a nontrivial amount of time to set up iCloud and return the requested URL, you should always call it from a secondary thread.
+     
+     - Parameter containerId: The fully-qualified container identifier for an iCloud container directory. The string you specify must not contain wildcards and must be of the form `<TEAMID>.<CONTAINER>`, where `<TEAMID>` is your development team ID and `<CONTAINER>` is the bundle identifier of the container you want to access.\
+         The container identifiers for your app must be declared in the `com.apple.developer.ubiquity-container-identifiers` array of the `.entitlements` property list file in your Xcode project.\
+         If you specify nil for this parameter, this method uses the first container listed in the `com.apple.developer.ubiquity-container-identifiers` entitlement array.
+     - Parameter scope: Use `.documents` (default) to put documents that the user is allowed to access inside a Documents subdirectory. Otherwise use `.data` to store user-related data files that your app needs to share but that are not files you want the user to manipulate directly.
+    */
+    public init? (containerId: String?, scope: UbiquitousScope = .documents) {
+        assert(!CloudFileProvider.asserting || !Thread.isMainThread, "LocalFileProvider.init(containerId:) is not recommended to be executed on Main Thread.")
+        guard FileManager.default.ubiquityIdentityToken != nil else {
            return nil
        }
        guard let ubiquityURL = FileManager.default.url(forUbiquityContainerIdentifier: containerId) else {
            return nil
        }
        self.containerId = containerId
-        let baseURL = ubiquityURL.standardized.appendingPathComponent("Documents/")
+        self.scope = scope
+        let baseURL: URL
+        if scope == .documents {
+            baseURL = ubiquityURL.appendingPathComponent("Documents/")
+        } else {
+            baseURL = ubiquityURL
+        }
+        
        super.init(baseURL: baseURL)
        self.isCoorinating = true
        
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(self.type)", attributes: DispatchQueue.Attributes.concurrent)
+        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: .concurrent)
        operation_queue = OperationQueue()
-        operation_queue.name = "FileProvider.\(self.type).Operation"
+        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
        
        fileManager.url(forUbiquityContainerIdentifier: containerId)
        opFileManager.url(forUbiquityContainerIdentifier: containerId)
@@ -49,14 +81,54 @@ open class CloudFileProvider: LocalFileProvider {
        try? fileManager.createDirectory(at: baseURL, withIntermediateDirectories: true)
    }
    
+    
+    public required convenience init?(coder aDecoder: NSCoder) {
+        guard let containerId = aDecoder.decodeObject(forKey: "containerId") as? String,
+            let scopeString = aDecoder.decodeObject(forKey: "scope") as? String,
+            let scope = UbiquitousScope(rawValue: scopeString) else {
+            return nil
+        }
+        self.init(containerId: containerId, scope: scope)
+        self.currentPath   = aDecoder.decodeObject(forKey: "currentPath") as? String ?? ""
+        self.isCoorinating = aDecoder.decodeBool(forKey: "isCoorinating")
+    }
+    
+    open override func encode(with aCoder: NSCoder) {
+        aCoder.encode(self.containerId, forKey: "containerId")
+        aCoder.encode(self.scope.rawValue, forKey: "scope")
+        aCoder.encode(self.currentPath, forKey: "currentPath")
+        aCoder.encode(self.isCoorinating, forKey: "isCoorinating")
+    }
+    
+    open override func copy(with zone: NSZone? = nil) -> Any {
+        let copy = CloudFileProvider(containerId: self.containerId, scope: self.scope)
+        copy?.currentPath = self.currentPath
+        copy?.delegate = self.delegate
+        copy?.fileOperationDelegate = self.fileOperationDelegate
+        return copy as Any
+    }
+    
+    /**
+     Returns an Array of `FileObject`s identifying the the directory entries via asynchronous completion handler.
+     
+     If the directory contains no entries or an error is occured, this method will return the empty array.
+     
+     - Parameter path: path to target directory. If empty, `currentPath` value will be used.
+     - Parameter completionHandler: a closure with result of directory entries or error.
+         `contents`: An array of `FileObject` identifying the the directory entries.
+         `error`: Error returned by system.
+     */
    open override func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
+        // FIXME: create runloop for dispatch_queue, start query on it
        dispatch_queue.async {
            let pathURL = self.url(of: path)
+            
            let query = NSMetadataQuery()
            query.predicate = NSPredicate(format: "%K BEGINSWITH %@", NSMetadataItemPathKey, pathURL.path)
-            query.searchScopes = [NSMetadataQueryUbiquitousDocumentsScope]
+            query.valueListAttributes = [NSMetadataItemURLKey, NSMetadataItemFSNameKey, NSMetadataItemPathKey, NSMetadataItemFSSizeKey, NSMetadataItemContentTypeTreeKey, NSMetadataItemFSCreationDateKey, NSMetadataItemFSContentChangeDateKey]
+            query.searchScopes = [self.scope.rawValue]
            var finishObserver: NSObjectProtocol?
-            finishObserver = NotificationCenter.default.addObserver(forName: NSNotification.Name.NSMetadataQueryDidFinishGathering, object: query, queue: nil, using: { (notification) in
+            finishObserver = NotificationCenter.default.addObserver(forName: .NSMetadataQueryDidFinishGathering, object: query, queue: nil, using: { (notification) in
                defer {
                    query.stop()
                    NotificationCenter.default.removeObserver(finishObserver!)
@@ -83,25 +155,47 @@ open class CloudFileProvider: LocalFileProvider {
                    }
                }
                
-                completionHandler(contents, nil)
+                query.stop()
+                self.dispatch_queue.async {
+                    completionHandler(contents, nil)
+                }
+                
            })
-            query.start()
+            DispatchQueue.main.async {
+                if !query.start() {
+                    self.dispatch_queue.async {
+                        completionHandler([], self.throwError(path, code: CocoaError.fileReadNoPermission))
+                    }
+                }
+            }
        }
    }
    
-    /// iCloud Storage size and free space is unavailable, it returns local space
+    /// Please don't rely this function to get iCloud drive total and remaining capacity
+    /// - Important: iCloud Storage size and free space is unavailable, it returns local space
    open override func storageProperties(completionHandler: (@escaping (_ total: Int64, _ used: Int64) -> Void)) {
        super.storageProperties(completionHandler: completionHandler)
    }
    
+    /**
+     Returns a `FileObject` containing the attributes of the item (file, directory, symlink, etc.) at the path in question via asynchronous completion handler.
+     
+     If the directory contains no entries or an error is occured, this method will return the empty `FileObject`.
+     
+     - Parameter path: path to target directory. If empty, `currentPath` value will be used.
+     - Parameter completionHandler: a closure with result of directory entries or error.
+         `attributes`: A `FileObject` containing the attributes of the item.
+         `error`: Error returned by system.
+     */
    open override func attributesOfItem(path: String, completionHandler: @escaping ((_ attributes: FileObject?, _ error: Error?) -> Void)) {
        dispatch_queue.async {
            let pathURL = self.url(of: path)
            let query = NSMetadataQuery()
            query.predicate = NSPredicate(format: "%K LIKE %@", NSMetadataItemPathKey, pathURL.path)
-            query.searchScopes = [NSMetadataQueryUbiquitousDocumentsScope]
+            query.valueListAttributes = [NSMetadataItemURLKey, NSMetadataItemFSNameKey, NSMetadataItemPathKey, NSMetadataItemFSSizeKey, NSMetadataItemContentTypeTreeKey, NSMetadataItemFSCreationDateKey, NSMetadataItemFSContentChangeDateKey]
+            query.searchScopes = [self.scope.rawValue]
            var finishObserver: NSObjectProtocol?
-            finishObserver = NotificationCenter.default.addObserver(forName: NSNotification.Name.NSMetadataQueryDidFinishGathering, object: query, queue: nil, using: { (notification) in
+            finishObserver = NotificationCenter.default.addObserver(forName: .NSMetadataQueryDidFinishGathering, object: query, queue: nil, using: { (notification) in
                defer {
                    query.stop()
                    NotificationCenter.default.removeObserver(finishObserver!)
@@ -111,51 +205,245 @@ open class CloudFileProvider: LocalFileProvider {
                
                guard let result = (query.results as? [NSMetadataItem])?.first, let attribs = result.values(forAttributes: [NSMetadataItemURLKey, NSMetadataItemFSNameKey, NSMetadataItemPathKey, NSMetadataItemFSSizeKey, NSMetadataItemContentTypeTreeKey, NSMetadataItemFSCreationDateKey, NSMetadataItemFSContentChangeDateKey]) else {
                    let error = self.throwError(path, code: CocoaError.fileNoSuchFile)
-                    completionHandler(nil, error)
+                    self.dispatch_queue.async {
+                        completionHandler(nil, error)
+                    }
                    return
                }
                
                if let file = self.mapFileObject(attributes: attribs) {
-                    completionHandler(file, nil)
+                    self.dispatch_queue.async {
+                        completionHandler(file, nil)
+                    }
                } else {
                    let noFileError = self.throwError(path, code: CocoaError.fileNoSuchFile)
-                    completionHandler(nil, noFileError)
+                    self.dispatch_queue.async {
+                        completionHandler(nil, noFileError)
+                    }
                }
            })
-            query.start()
+            DispatchQueue.main.async {
+                if !query.start() {
+                    self.dispatch_queue.async {
+                        completionHandler(nil, self.throwError(path, code: CocoaError.fileReadNoPermission))
+                    }
+                }
+            }
        }
    }
    
+    /**
+     Search files inside directory using query asynchronously.
+     
+     - Note: For now only it's limited to file names. `query` parameter may take `NSPredicate` format in near future.
+     
+     - Parameters:
+     - path: location of directory to start search
+     - recursive: Searching subdirectories of path
+     - query: Simple string of file name to be search (for now).
+     - foundItemHandler: Closure which is called when a file is found
+     - completionHandler: Closure which will be called after finishing search. Returns an arry of `FileObject` or error if occured.
+     */
+    open override func searchFiles(path: String, recursive: Bool, query: NSPredicate, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
+        
+        let mapDict: [String: String] = ["url": NSMetadataItemURLKey, "name": NSMetadataItemFSNameKey, "path": NSMetadataItemPathKey, "filesize": NSMetadataItemFSSizeKey, "modifiedDate": NSMetadataItemFSContentChangeDateKey, "creationDate": NSMetadataItemFSCreationDateKey, "contentType": NSMetadataItemContentTypeKey]
+        
+        func updateQueryKeys(_ queryComponent: NSPredicate) -> NSPredicate {
+            if let cQuery = queryComponent as? NSCompoundPredicate {
+                let newSub = cQuery.subpredicates.map { updateQueryKeys($0 as! NSPredicate) }
+                switch cQuery.compoundPredicateType {
+                case .and: return NSCompoundPredicate(andPredicateWithSubpredicates: newSub)
+                case .not: return NSCompoundPredicate(notPredicateWithSubpredicate: newSub.first!)
+                case .or:  return NSCompoundPredicate(orPredicateWithSubpredicates: newSub)
+                }
+            } else if let cQuery = queryComponent as? NSComparisonPredicate {
+                var newLeft = cQuery.leftExpression
+                var newRight = cQuery.rightExpression
+                if newLeft.expressionType == .keyPath, let newKey = mapDict[newLeft.keyPath] {
+                    newLeft = NSExpression(forKeyPath: newKey)
+                }
+                if newRight.expressionType == .keyPath, let newKey = mapDict[newRight.keyPath] {
+                    newRight = NSExpression(forKeyPath: newKey)
+                }
+                if newLeft.expressionType == .keyPath, newLeft.keyPath == "type" {
+                    newRight = NSExpression(forConstantValue: newRight.constantValue as? String == "directory" ? "public.directory": "public.data")
+                }
+                if newRight.expressionType == .keyPath, newRight.keyPath == "type" {
+                    newLeft = NSExpression(forConstantValue: newLeft.constantValue as? String == "directory" ? "public.directory": "public.data")
+                }
+                return NSComparisonPredicate(leftExpression: newLeft, rightExpression: newRight, modifier: cQuery.comparisonPredicateModifier, type: cQuery.predicateOperatorType, options: cQuery.options)
+            } else {
+                return queryComponent
+            }
+        }
+        
+        dispatch_queue.async {
+            let pathURL = self.url(of: path)
+            let mdquery = NSMetadataQuery()
+            mdquery.predicate = NSPredicate(format: "(%K BEGINSWITH %@) && (\(updateQueryKeys(query).predicateFormat))", NSMetadataItemPathKey, pathURL.path)
+            mdquery.searchScopes = [self.scope.rawValue]
+            
+            var lastReportedCount = 0
+            
+            if let foundItemHandler = foundItemHandler {
+                var updateObserver: NSObjectProtocol?
+                
+                // FIXME: Remove this section as it won't work as expected on iCloud
+                updateObserver = NotificationCenter.default.addObserver(forName: .NSMetadataQueryGatheringProgress, object: mdquery, queue: nil, using: { (notification) in
+                    
+                    mdquery.disableUpdates()
+                    
+                    guard mdquery.resultCount > lastReportedCount else { return }
+                    
+                    for index in lastReportedCount..<mdquery.resultCount {
+                        guard let attribs = (mdquery.result(at: index) as? NSMetadataItem)?.values(forAttributes: [NSMetadataItemURLKey, NSMetadataItemFSNameKey, NSMetadataItemPathKey, NSMetadataItemFSSizeKey, NSMetadataItemContentTypeTreeKey, NSMetadataItemFSCreationDateKey, NSMetadataItemFSContentChangeDateKey]) else {
+                            continue
+                        }
+                        
+                        guard let url = (attribs[NSMetadataItemURLKey] as? URL)?.standardized, recursive || url.deletingLastPathComponent().path.trimmingCharacters(in: pathTrimSet) == pathURL.path.trimmingCharacters(in: pathTrimSet) else {
+                            continue
+                        }
+                        
+                        if let file = self.mapFileObject(attributes: attribs) {
+                            foundItemHandler(file)
+                        }
+                    }
+                    lastReportedCount = mdquery.resultCount
+                    
+                    mdquery.enableUpdates()
+                })
+            }
+            
+            var finishObserver: NSObjectProtocol?
+            finishObserver = NotificationCenter.default.addObserver(forName: .NSMetadataQueryDidFinishGathering, object: mdquery, queue: nil, using: { (notification) in
+                defer {
+                    mdquery.stop()
+                    NotificationCenter.default.removeObserver(finishObserver!)
+                }
+                
+                guard let results = mdquery.results as? [NSMetadataItem] else {
+                    return
+                }
+                
+                mdquery.disableUpdates()
+                
+                var contents = [FileObject]()
+                for result in results {
+                    guard let attribs = result.values(forAttributes: [NSMetadataItemURLKey, NSMetadataItemFSNameKey, NSMetadataItemPathKey, NSMetadataItemFSSizeKey, NSMetadataItemContentTypeTreeKey, NSMetadataItemFSCreationDateKey, NSMetadataItemFSContentChangeDateKey]) else {
+                        continue
+                    }
+                    
+                    guard let url = (attribs[NSMetadataItemURLKey] as? URL)?.standardized, recursive || url.deletingLastPathComponent().path.trimmingCharacters(in: pathTrimSet) == pathURL.path.trimmingCharacters(in: pathTrimSet) else {
+                        continue
+                    }
+                    
+                    if let file = self.mapFileObject(attributes: attribs) {
+                        contents.append(file)
+                    }
+                }
+                self.dispatch_queue.async {
+                    completionHandler(contents, nil)
+                }
+            })
+            
+            DispatchQueue.main.async {
+                if !mdquery.start() {
+                    self.dispatch_queue.async {
+                        completionHandler([], self.throwError(path, code: CocoaError.fileReadNoPermission))
+                    }
+                }
+            }
+        }
+    }
+    
+    open override func isReachable(completionHandler: @escaping (Bool) -> Void) {
+        dispatch_queue.async {
+            completionHandler(self.fileManager.ubiquityIdentityToken != nil)
+        }
+    }
+    
+    /**
+     Creates a new directory at the specified path asynchronously.
+     This will create any necessary intermediate directories.
+     
+     - Parameters:
+       - folder: Directory name.
+       - at: Parent path of new directory.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+     - Returns: An `OperationHandle` to get progress or cancel progress. Doesn't work on `CloudFileProvider`.
+     */
    @discardableResult
    open override func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let r = super.create(folder: folderName, at: atPath, completionHandler: completionHandler)
-        return CloudOperationHandle(operationType: r!.operationType, baseURL: self.baseURL)
-    }
-    
-    @discardableResult
-    open override func create(file fileName: String, at atPath: String, contents data: Data?, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let r = super.create(file: fileName, at: atPath, contents: data, completionHandler: completionHandler)
-        return CloudOperationHandle(operationType: r!.operationType, baseURL: self.baseURL)
+        guard let r = super.create(folder: folderName, at: atPath, completionHandler: completionHandler) else { return nil }
+        return CloudOperationHandle(operationType: r.operationType, baseURL: self.baseURL)
    }
    
+    /**
+     Moves a file or directory from `path` to designated path asynchronously.
+     When you want move a file, destination path should also consists of file name.
+     Either a new name or the old one.
+     
+     - Parameters:
+       - path: original file or directory path.
+       - to: destination path of file or directory, including file/directory name.
+       - overwrite: Destination file should be overwritten if file is already exists. **Default** is `false`.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+     - Returns: An `OperationHandle` to get progress or cancel progress. Doesn't work on `CloudFileProvider`.
+     */
    @discardableResult
    open override func moveItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let r = super.moveItem(path: path, to: toPath, overwrite: overwrite, completionHandler: completionHandler)
-        return CloudOperationHandle(operationType: r!.operationType, baseURL: self.baseURL)
+        guard let r = super.moveItem(path: path, to: toPath, overwrite: overwrite, completionHandler: completionHandler) else { return nil }
+        return CloudOperationHandle(operationType: r.operationType, baseURL: self.baseURL)
    }
    
+    /**
+     Copies a file or directory from `path` to designated path asynchronously.
+     When want copy a file, destination path should also consists of file name.
+     Either a new name or the old one.
+     
+     - Parameters:
+       - path: original file or directory path.
+       - to: destination path of file or directory, including file/directory name.
+       - overwrite: Destination file should be overwritten if file is already exists. **Default** is `false`.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+     - Returns: An `OperationHandle` to get progress or cancel progress. Doesn't work on `CloudFileProvider`.
+     */
    @discardableResult
    open override func copyItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let r = super.copyItem(path: path, to: toPath, overwrite: overwrite, completionHandler: completionHandler)
-        return CloudOperationHandle(operationType: r!.operationType, baseURL: self.baseURL)
+        guard let r = super.copyItem(path: path, to: toPath, overwrite: overwrite, completionHandler: completionHandler) else { return nil }
+        return CloudOperationHandle(operationType: r.operationType, baseURL: self.baseURL)
    }
    
+    /**
+     Removes the file or directory at the specified path.
+     
+     - Important: Due to a bug (race condition?) in Apple API, it takes about 3-5 seconds to update containing folder
+       list and triggering notification registered for directory while completion handler will run almost immediately.
+       It's your responsibility to workaourd this bug/feature and mark file as deleted in your software.
+     
+     - Parameters:
+       - path: file or directory path.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+     - Returns: An `OperationHandle` to get progress or cancel progress. Doesn't work on `CloudFileProvider`.
+     
+     */
    @discardableResult
    open override func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let r = super.removeItem(path: path, completionHandler: completionHandler)
-        return CloudOperationHandle(operationType: r!.operationType, baseURL: self.baseURL)
+        guard let r = super.removeItem(path: path, completionHandler: completionHandler) else { return nil }
+        return CloudOperationHandle(operationType: r.operationType, baseURL: self.baseURL)
    }
    
+    /**
+     Uploads a file from local file url to designated path asynchronously.
+     Method will fail if source is not a local url with `file://` scheme.
+     
+     - Parameters:
+       - localFile: a file url to file.
+       - to: destination path of file, including file/directory name.
+       - overwrite: Destination file should be overwritten if file is already exists. **Default** is `false`.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+     - Returns: An `OperationHandle` to get progress or cancel progress.
+     */
    @discardableResult
    open override func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        // TODO: Make use of overwrite parameter
@@ -190,6 +478,16 @@ open class CloudFileProvider: LocalFileProvider {
        return CloudOperationHandle(operationType: opType, baseURL: self.baseURL)
    }
    
+    /**
+     Download a file from `path` to designated local file url asynchronously.
+     Method will fail if destination is not a local url with `file://` scheme.
+     
+     - Parameters:
+       - path: original file or directory path.
+       - toLocalURL: destination local url of file, including file/directory name.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+     - Returns: An `OperationHandle` to get progress or cancel progress.
+     */
    @discardableResult
    open override func copyItem(path: String, toLocalURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.copy(source: path, destination: toLocalURL.absoluteString)
@@ -204,108 +502,87 @@ open class CloudFileProvider: LocalFileProvider {
            return nil
        }
        
-        let r = super.copyItem(path: path, toLocalURL: toLocalURL, completionHandler: completionHandler)
-        return CloudOperationHandle(operationType: r!.operationType, baseURL: self.baseURL)
+        guard let r = super.copyItem(path: path, toLocalURL: toLocalURL, completionHandler: completionHandler) else { return nil }
+        return CloudOperationHandle(operationType: r.operationType, baseURL: self.baseURL)
    }
    
+    /**
+     Retreives a `Data` object with the contents of the file asynchronously vis contents argument of completion handler.
+     If path specifies a directory, or if some other error occurs, data will be nil.
+     
+     - Parameters:
+       - path: Path of file.
+       - completionHandler: a closure with result of file contents or error.
+         `contents`: contents of file in a `Data` object.
+         `error`: Error returned by system.
+     - Returns: An `OperationHandle` to get progress or cancel progress.
+     */
    @discardableResult
    open override func contents(path: String, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
-        let r = super.contents(path: path, completionHandler: completionHandler)
-        return CloudOperationHandle(operationType: r!.operationType, baseURL: self.baseURL)
+        guard let r = super.contents(path: path, completionHandler: completionHandler) else { return nil }
+        return CloudOperationHandle(operationType: r.operationType, baseURL: self.baseURL)
    }
    
+    /**
+     Retreives a `Data` object with a portion contents of the file asynchronously vis contents argument of completion handler.
+     If path specifies a directory, or if some other error occurs, data will be nil.
+     
+     - Parameters:
+       - path: Path of file.
+       - offset: First byte index which should be read. **Starts from 0.**
+       - length: Bytes count of data. Pass `-1` to read until the end of file.
+       - completionHandler: a closure with result of file contents or error.
+         `contents`: contents of file in a `Data` object.
+         `error`: Error returned by system.
+     - Returns: An `OperationHandle` to get progress or cancel progress.
+     */
    @discardableResult
    open override func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
-        let r = super.contents(path: path, offset: offset, length: length, completionHandler: completionHandler)
-        return CloudOperationHandle(operationType: r!.operationType, baseURL: self.baseURL)
+        guard let r = super.contents(path: path, offset: offset, length: length, completionHandler: completionHandler) else { return nil }
+        return CloudOperationHandle(operationType: r.operationType, baseURL: self.baseURL)
    }
    
+    /**
+     Write the contents of the `Data` to a location asynchronously.
+     
+     - Parameters:
+       - path: Path of target file.
+       - contents: Data to be written into file.
+       - overwrite: Destination file should be overwritten if file is already exists. Default is `false`.
+       - atomically: data will be written to a temporary file before writing to final location. Default is `false`.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+     - Returns: An `OperationHandle` to get progress or cancel progress. Doesn't work on `LocalFileProvider`.
+     */
    @discardableResult
-    open override func writeContents(path: String, contents data: Data, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let r = super.writeContents(path: path, contents: data, atomically: atomically, overwrite: overwrite, completionHandler: completionHandler)
-        return CloudOperationHandle(operationType: r!.operationType, baseURL: self.baseURL)
+    open override func writeContents(path: String, contents data: Data?, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        guard let r = super.writeContents(path: path, contents: data, atomically: atomically, overwrite: overwrite, completionHandler: completionHandler) else { return nil }
+        return CloudOperationHandle(operationType: r.operationType, baseURL: self.baseURL)
    }
    
-    open override func searchFiles(path: String, recursive: Bool, query: String, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
-        dispatch_queue.async {
-            let pathURL = self.url(of: path)
-            let query = NSMetadataQuery()
-            query.predicate = NSPredicate(format: "(%K BEGINSWITH %@) && (%K LIKE %@)", NSMetadataItemPathKey, pathURL.path, NSMetadataItemFSNameKey, query)
-            query.searchScopes = [NSMetadataQueryUbiquitousDocumentsScope]
-            
-            var lastReportedCount = 0
-            
-            if let foundItemHandler = foundItemHandler {
-                var updateObserver: NSObjectProtocol?
-                
-                updateObserver = NotificationCenter.default.addObserver(forName: .NSMetadataQueryGatheringProgress, object: query, queue: nil, using: { (notification) in
-                    
-                    query.disableUpdates()
-                    
-                    guard query.resultCount > lastReportedCount else { return }
-                    
-                    for index in lastReportedCount..<query.resultCount {
-                        guard let attribs = (query.result(at: index) as? NSMetadataItem)?.values(forAttributes: [NSMetadataItemURLKey, NSMetadataItemFSNameKey, NSMetadataItemPathKey, NSMetadataItemFSSizeKey, NSMetadataItemContentTypeTreeKey, NSMetadataItemFSCreationDateKey, NSMetadataItemFSContentChangeDateKey]) else {
-                            continue
-                        }
-                        
-                        guard let url = (attribs[NSMetadataItemURLKey] as? URL)?.standardized, recursive || url.deletingLastPathComponent().path.trimmingCharacters(in: pathTrimSet) == pathURL.path.trimmingCharacters(in: pathTrimSet) else {
-                            continue
-                        }
-                        
-                        if let file = self.mapFileObject(attributes: attribs) {
-                            foundItemHandler(file)
-                        }
-                    }
-                    lastReportedCount = query.resultCount
-                    
-                    query.enableUpdates()
-                })
-            }
-            
-            var finishObserver: NSObjectProtocol?
-            finishObserver = NotificationCenter.default.addObserver(forName: .NSMetadataQueryDidFinishGathering, object: query, queue: nil, using: { (notification) in
-                defer {
-                    query.stop()
-                    NotificationCenter.default.removeObserver(finishObserver!)
-                }
-                
-                guard let results = query.results as? [NSMetadataItem] else {
-                    return
-                }
-                
-                query.disableUpdates()
-                
-                var contents = [FileObject]()
-                for result in results {
-                    guard let attribs = result.values(forAttributes: [NSMetadataItemURLKey, NSMetadataItemFSNameKey, NSMetadataItemPathKey, NSMetadataItemFSSizeKey, NSMetadataItemContentTypeTreeKey, NSMetadataItemFSCreationDateKey, NSMetadataItemFSContentChangeDateKey]) else {
-                        continue
-                    }
-                    
-                    guard let url = (attribs[NSMetadataItemURLKey] as? URL)?.standardized, recursive || url.deletingLastPathComponent().path.trimmingCharacters(in: pathTrimSet) == pathURL.path.trimmingCharacters(in: pathTrimSet) else {
-                        continue
-                    }
-                    
-                    if let file = self.mapFileObject(attributes: attribs) {
-                        contents.append(file)
-                    }
-                }
-                
-                completionHandler(contents, nil)
-            })
-            
-            query.start()
-        }
-    }
+    fileprivate var monitors = [String: (NSMetadataQuery, NSObjectProtocol)]()
    
-    fileprivate var monitors = [URL: (NSMetadataQuery, NSObjectProtocol)]()
-    //
+    /**
+     Starts monitoring a path and its subpaths, including files and folders, for any change,
+     including copy, move/rename, content changes, etc.
+     To avoid thread congestion, `evetHandler` will be triggered with 0.2 seconds interval,
+     and has a 0.25 second delay, to ensure it's called after updates.
+     
+     - Note: this functionality is available only in `LocalFileProvider` and `CloudFileProvider`.
+     - Note: `eventHandler` is not called on main thread, for updating UI. dispatch routine to main thread.
+     - Important: `eventHandler` may be called if file is changed in recursive subpaths of registered path.
+     This may cause negative impact on performance if a root path is being monitored.
+     
+     - Parameters:
+       - path: path of directory.
+       - eventHandler: Closure executed after change, on a secondary thread.
+     */
    open override func registerNotifcation(path: String, eventHandler: @escaping (() -> Void)) {
        self.unregisterNotifcation(path: path)
        let pathURL = self.url(of: path)
        let query = NSMetadataQuery()
        query.predicate = NSPredicate(format: "(%K BEGINSWITH %@)", NSMetadataItemPathKey, pathURL.path)
-        query.searchScopes = [NSMetadataQueryUbiquitousDocumentsScope]
+        query.valueListAttributes = []
+        query.searchScopes = [self.scope.rawValue]
        
        let updateObserver = NotificationCenter.default.addObserver(forName: .NSMetadataQueryDidUpdate, object: query, queue: nil, using: { (notification) in
            
@@ -316,38 +593,36 @@ open class CloudFileProvider: LocalFileProvider {
            query.enableUpdates()
        })
        
-        query.start()
-        
-        monitors[pathURL] = (query, updateObserver)
+        DispatchQueue.main.async {
+            if query.start() {
+                self.monitors[path] = (query, updateObserver)
+            }
+        }
    }
    
+    /// Stops monitoring the path.
+    ///
+    /// - Parameter path: path of directory.
    open override func unregisterNotifcation(path: String) {
-        let key = url(of: path)
-        guard let (query, observer) = monitors[key] else {
+        guard let (query, observer) = monitors[path] else {
            return
        }
        query.disableUpdates()
        query.stop()
-        monitors.removeValue(forKey: key)
        NotificationCenter.default.removeObserver(observer)
+        monitors.removeValue(forKey: path)
    }
    
+    /// Investigate either the path is registered for change notification or not.
+    ///
+    /// - Parameter path: path of directory.
+    /// - Returns: Directory is being monitored or not.
    open override func isRegisteredForNotification(path: String) -> Bool {
-        return monitors[url(of: path)] != nil
-    }
-    
-    /// may return nil
-    open override func copy(with zone: NSZone? = nil) -> Any {
-        let copy = CloudFileProvider(containerId: self.containerId)
-        copy?.currentPath = self.currentPath
-        copy?.delegate = self.delegate
-        copy?.fileOperationDelegate = self.fileOperationDelegate
-        copy?.isPathRelative = self.isPathRelative
-        return copy as Any
+        return monitors[path] != nil
    }
    
    fileprivate func mapFileObject(attributes attribs: [String: Any]) -> FileObject? {
-        guard let url = (attribs[NSMetadataItemURLKey] as? URL)?.standardized, let name = attribs[NSMetadataItemFSNameKey] as? String else {
+        guard let url = (attribs[NSMetadataItemURLKey] as? URL)?.standardizedFileURL, let name = attribs[NSMetadataItemFSNameKey] as? String else {
            return nil
        }
        
@@ -366,7 +641,9 @@ open class CloudFileProvider: LocalFileProvider {
        return file
    }
    
-    /// Removes local copy of file, but spares cloud copy
+    /// Removes local copy of file, but spares cloud copy/
+    /// - Parameter path: Path of file or directory to be remoed from local
+    /// - Parameter completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
    open func evictItem(path: String, completionHandler: SimpleCompletionHandler) {
        operation_queue.addOperation {
            do {
@@ -378,21 +655,73 @@ open class CloudFileProvider: LocalFileProvider {
        }
    }
    
-    open func temporaryLink(to path: String, completionHandler: @escaping ((_ link: URL?, _ attribute: FileObject?, _ expiration: Date?, _ error: Error?) -> Void)) {
+    /**
+     Genrates a public url to a file to be shared with other users and can be downloaded without authentication.
+     
+     - Important: URL will be available for a limitied time, determined in `expiration` argument.
+     
+     - Parameters:
+     - to: path of file, including file/directory name.
+     - completionHandler: a closure with result of directory entries or error.
+     `link`: a url returned by Dropbox to share.
+     `attribute`: a `FileObject` containing the attributes of the item.
+     `expiration`: a `Date` object, determines when the public url will expires.
+     `error`: Error returned by Dropbox.
+     */
+    open func publicLink(to path: String, completionHandler: @escaping ((_ link: URL?, _ attribute: FileObject?, _ expiration: Date?, _ error: Error?) -> Void)) {
        operation_queue.addOperation {
            do {
                var expiration: NSDate?
                let url = try self.opFileManager.url(forPublishingUbiquitousItemAt: self.url(of: path), expiration: &expiration)
-                completionHandler(url, nil, expiration as Date?, nil)
+                self.dispatch_queue.async {
+                    completionHandler(url, nil, expiration as Date?, nil)
+                }
            } catch let e {
-                completionHandler(nil, nil, nil, e)
+                self.dispatch_queue.async {
+                    completionHandler(nil, nil, nil, e)
+                }
            }
        }
    }
 }

+public enum UbiquitousScope: RawRepresentable {
+    /// Search all files not in the Documents directories of the app’s iCloud container directories.
+    /// Use this scope to store user-related data files that your app needs to share 
+    /// but that are not files you want the user to manipulate directly.
+    case data
+    /// Search all files in the Documents directories of the app’s iCloud container directories.
+    /// Put documents that the user is allowed to access inside a Documents subdirectory.
+    case documents
+    
+    public typealias RawValue = String
+    
+    public init? (rawValue: String) {
+        switch rawValue {
+        case NSMetadataQueryUbiquitousDataScope:
+            self = .data
+        case NSMetadataQueryUbiquitousDocumentsScope:
+            self = .documents
+        default:
+            return nil
+        }
+    }
+    
+    public var rawValue: String {
+        switch self {
+        case .data:
+            return NSMetadataQueryUbiquitousDataScope
+        case .documents:
+            return NSMetadataQueryUbiquitousDocumentsScope
+        }
+    }
+}
+
+/// Get progress of CloudFileProvider operations
 open class CloudOperationHandle: OperationHandle {
+    /// Url of file which operation is doing on
    public let baseURL: URL?
+    /// Type of operation
    public let operationType: FileOperationType
    
    init (operationType: FileOperationType, baseURL: URL?) {
@@ -410,7 +739,6 @@ open class CloudOperationHandle: OperationHandle {
        return dest.hasPrefix("file://") ? URL(fileURLWithPath: dest) : baseURL.appendingPathComponent(dest)
    }
    
-    /// Caution: may put pressure on CPU, may have latency
    open var bytesSoFar: Int64 {
        assert(!Thread.isMainThread, "Don't run \(#function) method on main thread")
        
@@ -428,7 +756,6 @@ open class CloudOperationHandle: OperationHandle {
        return 0
    }
    
-    /// Caution: may put pressure on CPU, may have latency
    open var totalBytes: Int64 {
        assert(!Thread.isMainThread, "Don't run \(#function) method on main thread")
        guard let url = destURL ?? sourceURL, let item = CloudOperationHandle.getMetadataItem(url: url) else { return -1 }
@@ -444,18 +771,18 @@ open class CloudOperationHandle: OperationHandle {
    
    /// Not usable in local provider
    open func cancel() -> Bool {
-        
        return false
    }
    
    fileprivate static func getMetadataItem(url: URL) -> NSMetadataItem? {
        let query = NSMetadataQuery()
        query.predicate = NSPredicate(format: "(%K LIKE %@)", NSMetadataItemPathKey, url.path)
-        query.searchScopes = [NSMetadataQueryUbiquitousDocumentsScope]
+        query.searchScopes = [NSMetadataQueryUbiquitousDocumentsScope, NSMetadataQueryUbiquitousDataScope]
        
        var item: NSMetadataItem?
        
        let group = DispatchGroup()
+        group.enter()
        var finishObserver: NSObjectProtocol?
        finishObserver = NotificationCenter.default.addObserver(forName: .NSMetadataQueryDidFinishGathering, object: query, queue: nil, using: { (notification) in
            defer {
@@ -472,9 +799,10 @@ open class CloudOperationHandle: OperationHandle {
            
        })
        
-        group.enter()
-        query.start()
-        _ = group.wait(timeout: DispatchTime.now() + 30)
+        DispatchQueue.main.async {
+            query.start()
+        }
+        _ = group.wait(timeout: .now() + 30)
        return item
    }
 }
@@ -10,16 +10,20 @@
 import Foundation
 import CoreGraphics

-// Because this class uses NSURLSession, it's necessary to disable App Transport Security
-// in case of using this class with unencrypted HTTP connection.
-
+/**
+ Allows accessing to Dropbox stored files. This provider doesn't cache or save files internally, however you can
+ set `useCache` and `cache` properties to use Foundation `NSURLCache` system.
+ 
+ - Note: Uploading files and data are limited to 150MB, for now.
+ */
 open class DropboxFileProvider: FileProviderBasicRemote {
-    open static let type: String = "DropBox"
-    open let isPathRelative: Bool
+    open class var type: String { return "DropBox" }
    open let baseURL: URL?
    open var currentPath: String
    
+    /// Dropbox RPC API URL, which is equal with [https://api.dropboxapi.com/2/](https://api.dropboxapi.com/2/)
    open let apiURL: URL
+    /// Dropbox contents download/upload API URL, which is equal with [https://content.dropboxapi.com/2/](https://content.dropboxapi.com/2/)
    open let contentURL: URL
    
    open var dispatch_queue: DispatchQueue
@@ -30,7 +34,11 @@ open class DropboxFileProvider: FileProviderBasicRemote {
    }
    
    open weak var delegate: FileProviderDelegate?
-    open let credential: URLCredential?
+    open var credential: URLCredential? {
+        didSet {
+            sessionDelegate?.credential = self.credential
+        }
+    }
    open private(set) var cache: URLCache?
    public var useCache: Bool
    public var validatingCache: Bool
@@ -38,19 +46,52 @@ open class DropboxFileProvider: FileProviderBasicRemote {
    fileprivate var _session: URLSession?
    fileprivate var sessionDelegate: SessionDelegate?
    public var session: URLSession {
-        if _session == nil {
-            self.sessionDelegate = SessionDelegate(fileProvider: self, credential: credential)
-            let config = URLSessionConfiguration.default
-            config.urlCache = cache
-            config.requestCachePolicy = .returnCacheDataElseLoad
-            _session = URLSession(configuration: config, delegate: sessionDelegate as URLSessionDelegate?, delegateQueue: self.operation_queue)
+        get {
+            if _session == nil {
+                self.sessionDelegate = SessionDelegate(fileProvider: self)
+                let config = URLSessionConfiguration.default
+                config.urlCache = cache
+                config.requestCachePolicy = .returnCacheDataElseLoad
+                _session = URLSession(configuration: config, delegate: sessionDelegate as URLSessionDelegate?, delegateQueue: self.operation_queue)
+                _session!.sessionDescription = UUID().uuidString
+                initEmptySessionHandler(_session!.sessionDescription!)
+            }
+            return _session!
+        }
+        
+        set {
+            assert(newValue.delegate is SessionDelegate, "session instances should have a SessionDelegate instance as delegate.")
+            _session = newValue
+            if session.sessionDescription?.isEmpty ?? true {
+                _session?.sessionDescription = UUID().uuidString
+            }
+            self.sessionDelegate = newValue.delegate as? SessionDelegate
+            initEmptySessionHandler(_session!.sessionDescription!)
        }
-        return _session!
    }
    
-    public init? (credential: URLCredential?, cache: URLCache? = nil) {
+    fileprivate var _longpollSession: URLSession?
+    internal var longpollSession: URLSession {
+        if _longpollSession == nil {
+            let config = URLSessionConfiguration.default
+            config.timeoutIntervalForRequest = 600
+            _longpollSession = URLSession(configuration: config, delegate: nil, delegateQueue: nil)
+        }
+        return _longpollSession!
+    }
+    
+    /**
+     Initializer for Dropbox provider with given client ID and Token.
+     These parameters must be retrieved via [OAuth2 API of Dropbox](https://www.dropbox.com/developers/reference/oauth-guide).
+     
+     There are libraries like [p2/OAuth2](https://github.com/p2/OAuth2) or [OAuthSwift](https://github.com/OAuthSwift/OAuthSwift) which can facilate the procedure to retrieve token. 
+     The latter is easier to use and prefered. Also you can use [auth0/Lock](https://github.com/auth0/Lock.iOS-OSX) which provides graphical user interface.
+     
+     - Parameter credential: a `URLCredential` object with Client ID set as `user` and Token set as `password`.
+     - Parameter cache: A URLCache to cache downloaded files and contents.
+    */
+    public init(credential: URLCredential?, cache: URLCache? = nil) {
        self.baseURL = nil
-        self.isPathRelative = true
        self.currentPath = ""
        self.useCache = false
        self.validatingCache = true
@@ -60,14 +101,50 @@ open class DropboxFileProvider: FileProviderBasicRemote {
        self.apiURL = URL(string: "https://api.dropboxapi.com/2/")!
        self.contentURL = URL(string: "https://content.dropboxapi.com/2/")!
        
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: DispatchQueue.Attributes.concurrent)
+        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: .concurrent)
        operation_queue = OperationQueue()
        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
-
+    }
+    
+    public required convenience init?(coder aDecoder: NSCoder) {
+        self.init(credential: aDecoder.decodeObject(forKey: "credential") as? URLCredential)
+        self.currentPath     = aDecoder.decodeObject(forKey: "currentPath") as? String ?? ""
+        self.useCache        = aDecoder.decodeBool(forKey: "useCache")
+        self.validatingCache = aDecoder.decodeBool(forKey: "validatingCache")
+    }
+    
+    public func encode(with aCoder: NSCoder) {
+        aCoder.encode(self.credential, forKey: "credential")
+        aCoder.encode(self.currentPath, forKey: "currentPath")
+        aCoder.encode(self.useCache, forKey: "useCache")
+        aCoder.encode(self.validatingCache, forKey: "validatingCache")
+    }
+    
+    public static var supportsSecureCoding: Bool {
+        return true
+    }
+    
+    open func copy(with zone: NSZone? = nil) -> Any {
+        let copy = DropboxFileProvider(credential: self.credential, cache: self.cache)
+        copy.currentPath = self.currentPath
+        copy.delegate = self.delegate
+        copy.fileOperationDelegate = self.fileOperationDelegate
+        copy.useCache = self.useCache
+        copy.validatingCache = self.validatingCache
+        return copy
    }
    
    deinit {
-        _session?.invalidateAndCancel()
+        if let sessionuuid = _session?.sessionDescription {
+            removeSessionHandler(for: sessionuuid)
+        }
+        
+        if fileProviderCancelTasksOnInvalidating {
+            _session?.invalidateAndCancel()
+        } else {
+            _session?.finishTasksAndInvalidate()
+        }
+        
    }
    
    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
@@ -83,18 +160,18 @@ open class DropboxFileProvider: FileProviderBasicRemote {
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        let requestDictionary: [String: AnyObject] = ["path": correctPath(path)! as NSString]
-        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
+        request.httpBody = Data(jsonDictionary: requestDictionary)
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderDropboxError?
+            var serverError: FileProviderDropboxError?
            var fileObject: DropboxFileObject?
            if let response = response as? HTTPURLResponse {
                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
-                dbError = code != nil ? FileProviderDropboxError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
-                if let data = data, let jsonStr = String(data: data, encoding: .utf8), let json = jsonToDictionary(jsonStr), let file = DropboxFileObject(json: json) {
+                serverError = code != nil ? FileProviderDropboxError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
+                if let json = data?.deserializeJSON(), let file = DropboxFileObject(json: json) {
                    fileObject = file
                }
            }
-            completionHandler(fileObject, dbError ?? error)
+            completionHandler(fileObject, serverError ?? error)
        }) 
        task.resume()
    }
@@ -107,7 +184,7 @@ open class DropboxFileProvider: FileProviderBasicRemote {
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
            var totalSize: Int64 = -1
            var usedSize: Int64 = 0
-            if let data = data, let jsonStr = String(data: data, encoding: .utf8), let json = jsonToDictionary(jsonStr) {
+            if let json = data?.deserializeJSON() {
                totalSize = ((json["allocation"] as? NSDictionary)?["allocated"] as? NSNumber)?.int64Value ?? -1
                usedSize = (json["used"] as? NSNumber)?.int64Value ?? 0
            }
@@ -116,31 +193,57 @@ open class DropboxFileProvider: FileProviderBasicRemote {
        task.resume()
    }
    
+    open func searchFiles(path: String, recursive: Bool, query: NSPredicate, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
+        var foundFiles = [DropboxFileObject]()
+        if let queryStr = query.findValue(forKey: "name", operator: .beginsWith) as? String {
+            // Dropbox only support searching for file names begin with query in non-enterprise accounts.
+            // We will use it if there is a `name BEGINSWITH[c] "query"` in predicate, then filter to form final result.
+            search(path, query: queryStr, foundItem: { (file) in
+                if query.evaluate(with: file.mapPredicate()) {
+                    foundFiles.append(file)
+                    foundItemHandler?(file)
+                }
+            }, completionHandler: { (error) in
+                completionHandler(foundFiles, error)
+            })
+        } else {
+            // Dropbox doesn't support searching attributes natively. The workaround is to fallback to listing all files
+            // and filter it locally. It may have a network burden in case there is many files in Dropbox, so please use it concisely.
+            list(path, recursive: true, progressHandler: { (files, _, error) in
+                for file in files where query.evaluate(with: file.mapPredicate()) {
+                    foundItemHandler?(file)
+                }
+            }, completionHandler: { (files, _, error) in
+                let predicatedFiles = files.filter { query.evaluate(with: $0.mapPredicate()) }
+                completionHandler(predicatedFiles, error)
+            })
+        }
+    }
+    
+    open func isReachable(completionHandler: @escaping (Bool) -> Void) {
+        self.storageProperties { total, _ in
+            completionHandler(total > 0)
+        }
+    }
+    
    open weak var fileOperationDelegate: FileOperationDelegate?
 }

 extension DropboxFileProvider: FileProviderOperations {
-    
-    
-    public func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let path = (atPath as NSString).appendingPathComponent(folderName) + "/"
        return doOperation(.create(path: path), completionHandler: completionHandler)
    }
    
-    public func create(file fileName: String, at path: String, contents data: Data?, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let filePath = (path as NSString).appendingPathComponent(fileName)
-        return self.writeContents(path: filePath, contents: data ?? Data(), completionHandler: completionHandler)
-    }
-    
-    public func moveItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func moveItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        return doOperation(.move(source: path, destination: toPath), completionHandler: completionHandler)
    }
    
-    public func copyItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func copyItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        return doOperation(.copy(source: path, destination: toPath), completionHandler: completionHandler)
    }
    
-    public func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        return doOperation(.remove(path: path), completionHandler: completionHandler)
    }
    
@@ -174,21 +277,29 @@ extension DropboxFileProvider: FileProviderOperations {
        } else {
            requestDictionary["path"] = correctPath(sourcePath) as NSString?
        }
-        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
+        request.httpBody = Data(jsonDictionary: requestDictionary)
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderDropboxError?
+            var serverError: FileProviderDropboxError?
            if let response = response as? HTTPURLResponse, response.statusCode >= 300, let code = FileProviderHTTPErrorCode(rawValue: response.statusCode) {
-                 dbError = FileProviderDropboxError(code: code, path: sourcePath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
+                 serverError = FileProviderDropboxError(code: code, path: sourcePath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
            }
-            completionHandler?(dbError ?? error)
-            self.delegateNotify(operation, error: dbError ?? error)
+            completionHandler?(serverError ?? error)
+            self.delegateNotify(operation, error: serverError ?? error)
        })
        task.taskDescription = operation.json
        task.resume()
        return RemoteOperationHandle(operationType: operation, tasks: [task])
    }
    
-    public func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        // check file is not a folder
+        guard (try? localFile.resourceValues(forKeys: [.fileResourceTypeKey]))?.fileResourceType ?? .unknown == .regular else {
+            dispatch_queue.async {
+                completionHandler?(self.throwError(localFile.path, code: URLError.fileIsDirectory))
+            }
+            return nil
+        }
+        
        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
@@ -196,33 +307,34 @@ extension DropboxFileProvider: FileProviderOperations {
        return upload_simple(toPath, localFile: localFile, overwrite: overwrite, operation: opType, completionHandler: completionHandler)
    }
    
-    public func copyItem(path: String, toLocalURL destURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func copyItem(path: String, toLocalURL destURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.copy(source: path, destination: destURL.absoluteString)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
        }
        let url = URL(string: "files/download", relativeTo: contentURL)!
        var request = URLRequest(url: url)
-        request.httpMethod = "GET"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        let requestDictionary: [String: AnyObject] = ["path": path as NSString]
-        let requestJson = dictionaryToJSON(requestDictionary) ?? ""
+        let requestJson = String(jsonDictionary: requestDictionary) ?? ""
        request.setValue(requestJson, forHTTPHeaderField: "Dropbox-API-Arg")
-        let task = session.downloadTask(with: request, completionHandler: { (cacheURL, response, error) in
-            guard let cacheURL = cacheURL, let httpResponse = response as? HTTPURLResponse , httpResponse.statusCode < 300 else {
-                let code = FileProviderHTTPErrorCode(rawValue: (response as? HTTPURLResponse)?.statusCode ?? -1)
+        let task = session.downloadTask(with: request)
+        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = completionHandler
+        downloadCompletionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { tempURL in
+            guard let httpResponse = task.response as? HTTPURLResponse , httpResponse.statusCode < 300 else {
+                let code = FileProviderHTTPErrorCode(rawValue: (task.response as? HTTPURLResponse)?.statusCode ?? -1)
                let errorData : Data? = nil //Data(contentsOf:cacheURL) // TODO: Figure out how to get error response data for the error description
-                let dbError : FileProviderDropboxError? = code != nil ? FileProviderDropboxError(code: code!, path: path, errorDescription: String(data: errorData ?? Data(), encoding: .utf8)) : nil
-                completionHandler?(dbError ?? error)
+                let serverError : FileProviderDropboxError? = code != nil ? FileProviderDropboxError(code: code!, path: path, errorDescription: String(data: errorData ?? Data(), encoding: .utf8)) : nil
+                completionHandler?(serverError)
                return
            }
            do {
-                try FileManager.default.moveItem(at: cacheURL, to: destURL)
+                try FileManager.default.moveItem(at: tempURL, to: destURL)
                completionHandler?(nil)
            } catch let e {
                completionHandler?(e)
            }
-        })
+        }
        task.taskDescription = opType.json
        task.resume()
        return RemoteOperationHandle(operationType: opType, tasks: [task])
@@ -230,51 +342,59 @@ extension DropboxFileProvider: FileProviderOperations {
 }

 extension DropboxFileProvider: FileProviderReadWrite {
-    public func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
+    open func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
+        if length == 0 || offset < 0 {
+            dispatch_queue.async {
+                completionHandler(Data(), nil)
+            }
+            return nil
+        }
+        
        let opType = FileOperationType.fetch(path: path)
        let url = URL(string: "files/download", relativeTo: contentURL)!
        var request = URLRequest(url: url)
-        request.httpMethod = "GET"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        if length > 0 {
-            request.setValue("bytes=\(offset)-\(offset + length - 1)", forHTTPHeaderField: "Range")
+            request.setValue("bytes=\(offset)-\(offset + Int64(length) - 1)", forHTTPHeaderField: "Range")
        } else if offset > 0 && length < 0 {
            request.setValue("bytes=\(offset)-", forHTTPHeaderField: "Range")
        }
        let requestDictionary: [String: AnyObject] = ["path": correctPath(path)! as NSString]
-        request.setValue(dictionaryToJSON(requestDictionary), forHTTPHeaderField: "Dropbox-API-Arg")
-        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderDropboxError?
-            if let httpResponse = response as? HTTPURLResponse , httpResponse.statusCode >= 300, let code = FileProviderHTTPErrorCode(rawValue: httpResponse.statusCode) {
-                dbError = FileProviderDropboxError(code: code, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8))
+        request.setValue(String(jsonDictionary: requestDictionary), forHTTPHeaderField: "Dropbox-API-Arg")
+        let task = session.downloadTask(with: request)
+        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { error in
+            completionHandler(nil, error)
+        }
+        downloadCompletionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { tempURL in
+            guard let httpResponse = task.response as? HTTPURLResponse , httpResponse.statusCode < 300 else {
+                let code = FileProviderHTTPErrorCode(rawValue: (task.response as? HTTPURLResponse)?.statusCode ?? -1)
+                let errorData : Data? = nil //Data(contentsOf:cacheURL) // TODO: Figure out how to get error response data for the error description
+                let serverError : FileProviderDropboxError? = code != nil ? FileProviderDropboxError(code: code!, path: path, errorDescription: String(data: errorData ?? Data(), encoding: .utf8)) : nil
+                completionHandler(nil, serverError)
+                return
            }
-            let filedata = dbError ?? error == nil ? data : nil
-            completionHandler(filedata, dbError ?? error)
-        })
+            do {
+                let data = try Data(contentsOf: tempURL)
+                completionHandler(data, nil)
+            } catch let e {
+                completionHandler(nil, e)
+            }
+        }
        task.taskDescription = opType.json
        task.resume()
        return RemoteOperationHandle(operationType: opType, tasks: [task])
    }
    
-    public func writeContents(path: String, contents data: Data, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    public func writeContents(path: String, contents data: Data?, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.modify(path: path)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
        }
        // FIXME: remove 150MB restriction
-        return upload_simple(path, data: data, overwrite: overwrite, operation: opType, completionHandler: completionHandler)
-    }
-    
-    public func searchFiles(path: String, recursive: Bool, query: String, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
-        var foundFiles = [DropboxFileObject]()
-        search(path, query: query, foundItem: { (file) in
-            foundFiles.append(file)
-            foundItemHandler?(file)
-            }, completionHandler: { (error) in
-                completionHandler(foundFiles, error)
-        })
+        return upload_simple(path, data: data ?? Data(), overwrite: overwrite, operation: opType, completionHandler: completionHandler)
    }
    
+    /*
    fileprivate func registerNotifcation(path: String, eventHandler: (() -> Void)) {
        /* There is two ways to monitor folders changing in Dropbox. Either using webooks
         * which means you have to implement a server to translate it to push notifications
@@ -287,34 +407,40 @@ extension DropboxFileProvider: FileProviderReadWrite {
    fileprivate func unregisterNotifcation(path: String) {
        NotImplemented()
    }
-    
-    // TODO: Implement /copy_reference, /get_account & /get_current_account
+    */
+    // TODO: Implement /get_account & /get_current_account
 }

 extension DropboxFileProvider {
-    @available(*, deprecated, message: "Use DropboxFileProvider.temporaryLink(to:, completionHandler: (URL?, DropboxFileObject?, Date?,  Error?)) function instead.")
-    open func temporaryLink(to path: String, completionHandler: @escaping ((_ link: URL?, _ attribute: DropboxFileObject?, _ error: Error?) -> Void)) {
-        self.temporaryLink(to: path) { (url, file, _, error) in
-            completionHandler(url, file, error)
-        }
-    }
-    
-    open func temporaryLink(to path: String, completionHandler: @escaping ((_ link: URL?, _ attribute: DropboxFileObject?, _ expiration: Date?, _ error: Error?) -> Void)) {
+    /**
+     Genrates a public url to a file to be shared with other users and can be downloaded without authentication.
+     
+     - Important: URL will be available for a limitied time (4 hours according to Dropbox documentation).
+     
+     - Parameters:
+       - to: path of file, including file/directory name.
+       - completionHandler: a closure with result of directory entries or error.
+         - `link`: a url returned by Dropbox to share.
+         - `attribute`: a `FileObject` containing the attributes of the item.
+         - `expiration`: a `Date` object, determines when the public url will expires.
+         - `error`: Error returned by Dropbox.
+    */
+    open func publicLink(to path: String, completionHandler: @escaping ((_ link: URL?, _ attribute: DropboxFileObject?, _ expiration: Date?, _ error: Error?) -> Void)) {
        let url = URL(string: "files/get_temporary_link", relativeTo: apiURL)!
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        let requestDictionary: [String: AnyObject] = ["path": correctPath(path)! as NSString]
-        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
+        request.httpBody = Data(jsonDictionary: requestDictionary)
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderDropboxError?
+            var serverError: FileProviderDropboxError?
            var link: URL?
            var fileObject: DropboxFileObject?
            if let response = response as? HTTPURLResponse {
                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
-                dbError = code != nil ? FileProviderDropboxError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
-                if let data = data, let jsonStr = String(data: data, encoding: .utf8), let json = jsonToDictionary(jsonStr) {
+                serverError = code != nil ? FileProviderDropboxError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
+                if let json = data?.deserializeJSON() {
                    if let linkStr = json["link"] as? String {
                        link = URL(string: linkStr)
                    }
@@ -325,60 +451,83 @@ extension DropboxFileProvider {
            }
            
            let expiration: Date? = link != nil ? Date(timeIntervalSinceNow: 4 * 60 * 60) : nil
-            completionHandler(link, fileObject, expiration, dbError ?? error)
+            completionHandler(link, fileObject, expiration, serverError ?? error)
        })
        task.resume()
    }
    
+    /**
+     Downloads a file from remote url to designated path asynchronously.
+     
+     - Parameters:
+       - remoteURL: a valid remote url to file.
+       - to: Destination path of file, including file/directory name.
+       - completionHandler: a closure with result of directory entries or error.
+         - `jobId`: Job ID returned by Dropbox to monitor the copy/download progress.
+         - `attribute`: A `FileObject` containing the attributes of the item.
+         - `error`: Error returned by Dropbox.
+     */
    open func copyItem(remoteURL: URL, to toPath: String, completionHandler: @escaping ((_ jobId: String?, _ attribute: DropboxFileObject?, _ error: Error?) -> Void)) {
+        if remoteURL.isFileURL {
+            completionHandler(nil, nil, self.throwError(remoteURL.path, code: URLError.badURL))
+            return
+        }
        let url = URL(string: "files/save_url", relativeTo: apiURL)!
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        let requestDictionary: [String: AnyObject] = ["path": correctPath(toPath)! as NSString, "url" : remoteURL.absoluteString as NSString]
-        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
+        request.httpBody = Data(jsonDictionary: requestDictionary)
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderDropboxError?
+            var serverError: FileProviderDropboxError?
            var jobId: String?
            var fileObject: DropboxFileObject?
            if let response = response as? HTTPURLResponse {
                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
-                dbError = code != nil ? FileProviderDropboxError(code: code!, path: toPath, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
-                if let data = data, let jsonStr = String(data: data, encoding: .utf8), let json = jsonToDictionary(jsonStr) {
+                serverError = code != nil ? FileProviderDropboxError(code: code!, path: toPath, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
+                if let json = data?.deserializeJSON() {
                    jobId = json["async_job_id"] as? String
                    if let attribDic = json["metadata"] as? [String: AnyObject] {
                        fileObject = DropboxFileObject(json: attribDic)
                    }
                }
            }
-            completionHandler(jobId, fileObject, dbError ?? error)
+            completionHandler(jobId, fileObject, serverError ?? error)
        })
        task.resume()
    }
    
-    open func copyItem(reference: String, to toPath: String, completionHandler:SimpleCompletionHandler) {
-        let url = URL(string: "files/save_url", relativeTo: apiURL)!
+    /**
+     Copys a file from another user Dropbox storage to designated path asynchronously.
+     
+     - Parameters:
+       - reference: a valid reference string from another user via `copy_reference/get` REST method.
+       - to: Destination path of file, including file/directory name.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+     */
+    open func copyItem(reference: String, to toPath: String, completionHandler: SimpleCompletionHandler) {
+        let url = URL(string: "files/copy_reference/save", relativeTo: apiURL)!
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        let requestDictionary: [String: AnyObject] = ["path": correctPath(toPath)! as NSString, "copy_reference" : reference as NSString]
-        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
+        request.httpBody = Data(jsonDictionary: requestDictionary)
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderDropboxError?
+            var serverError: FileProviderDropboxError?
            if let response = response as? HTTPURLResponse {
                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
-                dbError = code != nil ? FileProviderDropboxError(code: code!, path: toPath, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
+                serverError = code != nil ? FileProviderDropboxError(code: code!, path: toPath, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
            }
-            completionHandler?(dbError ?? error)
+            completionHandler?(serverError ?? error)
        })
        task.resume()
    }
 }

 extension DropboxFileProvider: ExtendedFileProvider {
-    public func thumbnailOfFileSupported(path: String) -> Bool {
+    open func thumbnailOfFileSupported(path: String) -> Bool {
        switch (path as NSString).pathExtension.lowercased() {
        case "jpg", "jpeg", "gif", "bmp", "png", "tif", "tiff":
            return true
@@ -393,7 +542,7 @@ extension DropboxFileProvider: ExtendedFileProvider {
        }
    }
    
-    public func propertiesOfFileSupported(path: String) -> Bool {
+    open func propertiesOfFileSupported(path: String) -> Bool {
        let fileExt = (path as NSString).pathExtension.lowercased()
        switch fileExt {
        case "jpg", "jpeg", "bmp", "gif", "png", "tif", "tiff":
@@ -408,7 +557,7 @@ extension DropboxFileProvider: ExtendedFileProvider {
    }
        
    /// Default value for dimension is 64x64, according to Dropbox documentation
-    public func thumbnailOfFile(path: String, dimension: CGSize?, completionHandler: @escaping ((_ image: ImageClass?, _ error: Error?) -> Void)) {
+    open func thumbnailOfFile(path: String, dimension: CGSize?, completionHandler: @escaping ((_ image: ImageClass?, _ error: Error?) -> Void)) {
        let url: URL
        switch (path as NSString).pathExtension.lowercased() {
        case "jpg", "jpeg", "gif", "bmp", "png", "tif", "tiff":
@@ -429,17 +578,17 @@ extension DropboxFileProvider: ExtendedFileProvider {
        if let dimension = dimension {
            requestDictionary["size"] = "w\(Int(dimension.width))h\(Int(dimension.height))" as NSString
        }
-        request.setValue(dictionaryToJSON(requestDictionary), forHTTPHeaderField: "Dropbox-API-Arg")
+        request.setValue(String(jsonDictionary: requestDictionary), forHTTPHeaderField: "Dropbox-API-Arg")
        let task = self.session.dataTask(with: request, completionHandler: { (data, response, error) in
            var image: ImageClass? = nil
-            if let r = response as? HTTPURLResponse, let result = r.allHeaderFields["Dropbox-API-Result"] as? String, let jsonResult = jsonToDictionary(result) {
+            if let r = response as? HTTPURLResponse, let result = r.allHeaderFields["Dropbox-API-Result"] as? String, let jsonResult = result.deserializeJSON() {
                if jsonResult["error"] != nil {
                    completionHandler(nil, self.throwError(path, code: URLError.cannotDecodeRawData as FoundationErrorEnum))
                }
            }
            if let data = data {
-                if DropboxFileProvider.dataIsPDF(data) {
-                    image = DropboxFileProvider.convertToImage(pdfData: data)
+                if data.isPDF, let pageImage = DropboxFileProvider.convertToImage(pdfData: data) {
+                    image = pageImage
                } else if let contentType = (response as? HTTPURLResponse)?.allHeaderFields["Content-Type"] as? String, contentType.contains("text/html") {
                     // TODO: Implement converting html returned type of get_preview to image
                } else {
@@ -451,39 +600,29 @@ extension DropboxFileProvider: ExtendedFileProvider {
        task.resume()
    }
    
-    public func propertiesOfFile(path: String, completionHandler: @escaping ((_ propertiesDictionary: [String : Any], _ keys: [String], _ error: Error?) -> Void)) {
+    open func propertiesOfFile(path: String, completionHandler: @escaping ((_ propertiesDictionary: [String : Any], _ keys: [String], _ error: Error?) -> Void)) {
        let url = URL(string: "files/get_metadata", relativeTo: apiURL)!
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        let requestDictionary: [String: AnyObject] = ["path": correctPath(path)! as NSString, "include_media_info": NSNumber(value: true)]
-        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
+        request.httpBody = Data(jsonDictionary: requestDictionary)
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderDropboxError?
+            var serverError: FileProviderDropboxError?
            var dic = [String: Any]()
            var keys = [String]()
            if let response = response as? HTTPURLResponse {
                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
-                dbError = code != nil ? FileProviderDropboxError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
-                if let data = data, let jsonStr = String(data: data, encoding: .utf8), let json = jsonToDictionary(jsonStr), let properties = json["media_info"] as? [String: Any] {
+                serverError = code != nil ? FileProviderDropboxError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
+                if let json = data?.deserializeJSON(), let properties = json["media_info"] as? [String: Any] {
                    (dic, keys) = self.mapMediaInfo(properties)
                }
            }
-            completionHandler(dic, keys, dbError ?? error)
+            completionHandler(dic, keys, serverError ?? error)
        })
        task.resume()
    }
 }

-extension DropboxFileProvider: FileProvider {
-    open func copy(with zone: NSZone? = nil) -> Any {
-        let copy = DropboxFileProvider(credential: self.credential, cache: self.cache)!
-        copy.currentPath = self.currentPath
-        copy.delegate = self.delegate
-        copy.fileOperationDelegate = self.fileOperationDelegate
-        copy.useCache = self.useCache
-        copy.validatingCache = self.validatingCache
-        return copy
-    }
-}
+extension DropboxFileProvider: FileProvider { }
@@ -8,23 +8,21 @@

 import Foundation

-public struct FileProviderDropboxError: Error, CustomStringConvertible {
+/// Error returned by Dropbox server when trying to access or do operations on a file or folder.
+public struct FileProviderDropboxError: FileProviderHTTPError {
    public let code: FileProviderHTTPErrorCode
    public let path: String
    public let errorDescription: String?
-    
-    public var description: String {
-        return code.description
-    }
 }

+/// Containts path, url and attributes of a Dropbox file or resource.
 public final class DropboxFileObject: FileObject {
    internal init(name: String, path: String) {
        super.init(url: URL(string: path) ?? URL(string: "/")!, name: name, path: path)
    }
    
    internal convenience init? (jsonStr: String) {
-        guard let json = jsonToDictionary(jsonStr) else { return nil }
+        guard let json = jsonStr.deserializeJSON() else { return nil }
        self.init(json: json)
    }
    
@@ -33,45 +31,51 @@ public final class DropboxFileObject: FileObject {
        guard let path = json["path_display"] as? String else { return nil }
        self.init(name: name, path: path)
        self.size = (json["size"] as? NSNumber)?.int64Value ?? -1
-        self.serverTime = resolve(dateString: json["server_modified"] as? String ?? "")
-        self.modifiedDate = resolve(dateString: json["client_modified"] as? String ?? "")
+        self.serverTime = Date(rfcString: json["server_modified"] as? String ?? "")
+        self.modifiedDate = Date(rfcString: json["client_modified"] as? String ?? "")
        self.type = (json[".tag"] as? String) == "folder" ? .directory : .regular
        self.isReadOnly = (json["sharing_info"]?["read_only"] as? NSNumber)?.boolValue ?? false
        self.id = json["id"] as? String
        self.rev = json["rev"] as? String
    }
    
+    /// The time contents of file has been modified on server, returns nil if not set
    open internal(set) var serverTime: Date? {
        get {
-            return allValues["NSURLServerDateKey"] as? Date
+            return allValues[.serverDateKey] as? Date
        }
        set {
-            allValues["NSURLServerDateKey"] = newValue
+            allValues[.serverDateKey] = newValue
        }
    }
    
+    /// The document identifier is a value assigned by the Dropbox to a file.
+    /// This value is used to identify the document regardless of where it is moved on a volume.
+    /// The identifier persists across system restarts.
    open internal(set) var id: String? {
        get {
-            return allValues["NSURLDocumentIdentifyKey"] as? String
+            return allValues[.documentIdentifierKey] as? String
        }
        set {
-            allValues["NSURLDocumentIdentifyKey"] = newValue
+            allValues[.documentIdentifierKey] = newValue
        }
    }
    
+    /// The revision of file, which changes when a file contents are modified.
+    /// Changes to attributes or other file metadata do not change the identifier.
    open internal(set) var rev: String? {
        get {
-            return allValues[URLResourceKey.generationIdentifierKey.rawValue] as? String
+            return allValues[.generationIdentifierKey] as? String
        }
        set {
-            allValues[URLResourceKey.generationIdentifierKey.rawValue] = newValue
+            allValues[.generationIdentifierKey] = newValue
        }
    }
 }

- // codebeat:disable[ARITY]
+// codebeat:disable[ARITY]
 internal extension DropboxFileProvider {
-    func list(_ path: String, cursor: String? = nil, prevContents: [DropboxFileObject] = [], recursive: Bool = false, completionHandler: @escaping ((_ contents: [FileObject], _ cursor: String?, _ error: Error?) -> Void)) {
+    func list(_ path: String, cursor: String? = nil, prevContents: [DropboxFileObject] = [], recursive: Bool = false, session: URLSession? = nil, progressHandler: ((_ contents: [FileObject], _ nextCursor: String?, _ error: Error?) -> Void)? = nil, completionHandler: @escaping ((_ contents: [FileObject], _ cursor: String?, _ error: Error?) -> Void)) {
        var requestDictionary = [String: AnyObject]()
        let url: URL
        if let cursor = cursor {
@@ -86,69 +90,39 @@ internal extension DropboxFileProvider {
        request.httpMethod = "POST"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
-        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
-        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
+        request.httpBody = Data(jsonDictionary: requestDictionary)
+        let task = (session ?? self.session).dataTask(with: request, completionHandler: { (data, response, error) in
            var responseError: FileProviderDropboxError?
-            var files = prevContents
+            var files = [DropboxFileObject]()
            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
                responseError = FileProviderDropboxError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8))
            }
-            if let data = data, let jsonStr = String(data: data, encoding: .utf8) {
-                let json = jsonToDictionary(jsonStr)
-                if let entries = json?["entries"] as? [AnyObject] , entries.count > 0 {
+            if let json = data?.deserializeJSON() {
+                if let entries = json["entries"] as? [AnyObject] , entries.count > 0 {
+                    files.reserveCapacity(entries.count)
                    for entry in entries {
                        if let entry = entry as? [String: AnyObject], let file = DropboxFileObject(json: entry) {
                            files.append(file)
                        }
                    }
-                    let ncursor = json?["cursor"] as? String
-                    let hasmore = (json?["has_more"] as? NSNumber)?.boolValue ?? false
+                    let ncursor = json["cursor"] as? String
+                    let hasmore = (json["has_more"] as? NSNumber)?.boolValue ?? false
                    if hasmore {
-                        self.list(path, cursor: ncursor, prevContents: files, completionHandler: completionHandler)
+                        progressHandler?(files, ncursor, responseError ?? error)
+                        self.list(path, cursor: ncursor, prevContents: prevContents + files, completionHandler: completionHandler)
                        return
                    }
                }
            }
-            completionHandler(files, nil, responseError ?? error)
+            progressHandler?(files, nil, responseError ?? error)
+            completionHandler(prevContents + files, nil, responseError ?? error)
        })
        task.taskDescription = FileOperationType.fetch(path: path).json
        task.resume()
    }
    
-    func upload_simple(_ targetPath: String, data: Data, modifiedDate: Date = Date(), overwrite: Bool, operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        if data.count > 150 * 1024 * 1024 {
-            let error = FileProviderDropboxError(code: .payloadTooLarge, path: targetPath, errorDescription: nil)
-            completionHandler?(error)
-            self.delegateNotify(.create(path: targetPath), error: error)
-            return nil
-        }
-        var requestDictionary = [String: AnyObject]()
-        let url: URL
-        url = URL(string: "files/upload", relativeTo: contentURL)!
-        requestDictionary["path"] = correctPath(targetPath) as NSString?
-        requestDictionary["mode"] = (overwrite ? "overwrite" : "add") as NSString
-        requestDictionary["client_modified"] = rfc3339utc(of: modifiedDate) as NSString
-        var request = URLRequest(url: url)
-        request.httpMethod = "POST"
-        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        request.setValue("application/octet-stream", forHTTPHeaderField: "Content-Type")
-        request.setValue(dictionaryToJSON(requestDictionary), forHTTPHeaderField: "Dropbox-API-Arg")
-        request.httpBody = data
-        let task = session.uploadTask(with: request, from: data, completionHandler: { (data, response, error) in
-            var responseError: FileProviderDropboxError?
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderDropboxError(code: rCode, path: targetPath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
-            }
-            completionHandler?(responseError ?? error)
-            self.delegateNotify(.create(path: targetPath), error: responseError ?? error)
-        })
-        task.taskDescription = operation.json
-        task.resume()
-        return RemoteOperationHandle(operationType: operation, tasks: [task])
-    }
-    
-    func upload_simple(_ targetPath: String, localFile: URL, modifiedDate: Date = Date(), overwrite: Bool, operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let size = (try? localFile.resourceValues(forKeys: [.fileSizeKey]))?.fileSize ?? -1
+    func upload_simple(_ targetPath: String, data: Data? = nil, localFile: URL? = nil, modifiedDate: Date = Date(), overwrite: Bool, operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let size = data?.count ?? Int((try? localFile?.resourceValues(forKeys: [.fileSizeKey]))??.fileSize ?? -1)
        if size > 150 * 1024 * 1024 {
            let error = FileProviderDropboxError(code: .payloadTooLarge, path: targetPath, errorDescription: nil)
            completionHandler?(error)
@@ -160,20 +134,30 @@ internal extension DropboxFileProvider {
        url = URL(string: "files/upload", relativeTo: contentURL)!
        requestDictionary["path"] = correctPath(targetPath) as NSString?
        requestDictionary["mode"] = (overwrite ? "overwrite" : "add") as NSString
-        requestDictionary["client_modified"] = rfc3339utc(of: modifiedDate) as NSString
+        requestDictionary["client_modified"] = modifiedDate.rfc3339utc() as NSString
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        request.setValue("application/octet-stream", forHTTPHeaderField: "Content-Type")
-        request.setValue(dictionaryToJSON(requestDictionary), forHTTPHeaderField: "Dropbox-API-Arg")
-        let task = session.uploadTask(with: request, fromFile: localFile, completionHandler: { (data, response, error) in
+        request.setValue(String(jsonDictionary: requestDictionary), forHTTPHeaderField: "Dropbox-API-Arg")
+        let task: URLSessionUploadTask
+        if let data = data {
+            task = session.uploadTask(with: request, from: data)
+        } else if let localFile = localFile {
+            task = session.uploadTask(with: request, fromFile: localFile)
+        } else {
+            return nil
+        }
+        
+        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { [weak self] error in
            var responseError: FileProviderDropboxError?
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderDropboxError(code: rCode, path: targetPath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
+            if let code = (task.response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
+                // We can't fetch server result from delegate!
+                responseError = FileProviderDropboxError(code: rCode, path: targetPath, errorDescription: nil)
            }
            completionHandler?(responseError ?? error)
-            self.delegateNotify(.create(path: targetPath), error: responseError ?? error)
-        })
+            self?.delegateNotify(.create(path: targetPath), error: responseError ?? error)
+        }
        task.taskDescription = operation.json
        task.resume()
        return RemoteOperationHandle(operationType: operation, tasks: [task])
@@ -189,22 +173,21 @@ internal extension DropboxFileProvider {
        requestDictionary["query"] = query as NSString
        requestDictionary["start"] = start as NSNumber
        requestDictionary["max_results"] = maxResultPerPage as NSNumber
-        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
+        request.httpBody = Data(jsonDictionary: requestDictionary)
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
            var responseError: FileProviderDropboxError?
            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
                responseError = FileProviderDropboxError(code: rCode, path: startPath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
            }
-            if let data = data, let jsonStr = String(data: data, encoding: .utf8) {
-                let json = jsonToDictionary(jsonStr)
-                if let entries = json?["matches"] as? [AnyObject] , entries.count > 0 {
+            if let json = data?.deserializeJSON() {
+                if let entries = json["matches"] as? [AnyObject] , entries.count > 0 {
                    for entry in entries {
                        if let entry = entry as? [String: AnyObject], let file = DropboxFileObject(json: entry) {
                            foundItem(file)
                        }
                    }
-                    let rstart = json?["start"] as? Int
-                    let hasmore = (json?["more"] as? NSNumber)?.boolValue ?? false
+                    let rstart = json["start"] as? Int
+                    let hasmore = (json["more"] as? NSNumber)?.boolValue ?? false
                    if hasmore, let rstart = rstart {
                        self.search(startPath, query: query, start: rstart + entries.count, maxResultPerPage: maxResultPerPage, foundItem: foundItem, completionHandler: completionHandler)
                    } else {
@@ -236,18 +219,18 @@ internal extension DropboxFileProvider {
            DropboxFileProvider.decimalFormatter.numberStyle = .decimal
            DropboxFileProvider.decimalFormatter.maximumFractionDigits = 5
            keys.append("Location")
-            let latStr = DropboxFileProvider.decimalFormatter.string(from: NSNumber(value: latitude))
-            let longStr = DropboxFileProvider.decimalFormatter.string(from: NSNumber(value: longitude))
+            let latStr = DropboxFileProvider.decimalFormatter.string(from: NSNumber(value: latitude))!
+            let longStr = DropboxFileProvider.decimalFormatter.string(from: NSNumber(value: longitude))!
            dic["Location"] = "\(latStr), \(longStr)"
        }
-        if let timeTakenStr = json["time_taken"] as? String, let timeTaken = resolve(dateString: timeTakenStr) {
+        if let timeTakenStr = json["time_taken"] as? String, let timeTaken = Date(rfcString: timeTakenStr) {
            keys.append("Date taken")
            DropboxFileProvider.dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
            dic["Date taken"] = DropboxFileProvider.dateFormatter.string(from: timeTaken)
        }
        if let duration = json["duration"] as? UInt64 {
            keys.append("Duration")
-            dic["Duration"] = DropboxFileProvider.formatshort(interval: TimeInterval(duration))
+            dic["Duration"] = TimeInterval(duration).formatshort
        }
        return (dic, keys)
    }
@@ -10,14 +10,8 @@ import Foundation
 import ImageIO
 import CoreGraphics
 import AVFoundation
-#if os(iOS) || os(tvOS)
-import UIKit
-#elseif os(macOS)
-import Cocoa
-#endif

 extension LocalFileProvider: ExtendedFileProvider {
-    
    public func thumbnailOfFileSupported(path: String) -> Bool {
        switch (path as NSString).pathExtension.lowercased() {
        case LocalFileInformationGenerator.imageThumbnailExtensions:
@@ -61,6 +55,7 @@ extension LocalFileProvider: ExtendedFileProvider {
    }
    
    public func thumbnailOfFile(path: String, dimension: CGSize? = nil, completionHandler: @escaping ((_ image: ImageClass?, _ error: Error?) -> Void)) {
+        let dimension = dimension ?? CGSize(width: 64, height: 64)
        (dispatch_queue).async {
            var thumbnailImage: ImageClass? = nil
            // Check cache
@@ -85,7 +80,7 @@ extension LocalFileProvider: ExtendedFileProvider {
            }
            
            if let image = thumbnailImage {
-                let scaledImage = dimension != nil ? LocalFileProvider.scaleDown(image: image, toSize: dimension!) : image
+                let scaledImage = LocalFileProvider.scaleDown(image: image, toSize: dimension)
                completionHandler(scaledImage, nil)
            }
        }
@@ -122,30 +117,83 @@ extension LocalFileProvider: ExtendedFileProvider {
            
            completionHandler(dic, keys, nil)
        }
-        
    }
 }

+/// Holds supported file types and thumbnail/properties generator for specefied type of file
 public struct LocalFileInformationGenerator {
-    static public var imageThumbnailExtensions: [String] = ["jpg", "jpeg", "gif", "bmp", "png", "tif", "tiff", "ico"]
-    static public var audioThumbnailExtensions: [String] = ["mp3", "aac", "m4a"]
-    static public var videoThumbnailExtensions: [String] = ["mov", "mp4", "m4v", "mpg", "mpeg"]
-    static public var pdfThumbnailExtensions: [String] = ["pdf"]
+    /// Image extensions supportes for thumbnail.
+    ///
+    /// Default: `["jpg", "jpeg", "gif", "bmp", "png", "tif", "tiff", "ico"]`
+    static public var imageThumbnailExtensions: [String]  = ["jpg", "jpeg", "gif", "bmp", "png", "tif", "tiff", "ico"]
+    
+    /// Audio and music extensions supportes for thumbnail.
+    ///
+    /// Default: `["mp3", "aac", "m4a"]`
+    static public var audioThumbnailExtensions: [String]  = ["mp3", "aac", "m4a"]
+    
+    /// Video extensions supportes for thumbnail.
+    ///
+    /// Default: `["mov", "mp4", "m4v", "mpg", "mpeg"]`
+    static public var videoThumbnailExtensions: [String]  = ["mov", "mp4", "m4v", "mpg", "mpeg"]
+    
+    /// Portable document file extensions supportes for thumbnail.
+    ///
+    /// Default: `["pdf"]`
+    static public var pdfThumbnailExtensions: [String]    = ["pdf"]
+    
+    /// Office document extensions supportes for thumbnail.
+    ///
+    /// Default: `empty`
    static public var officeThumbnailExtensions: [String] = []
+    
+    /// Custom document extensions supportes for thumbnail.
+    ///
+    /// Default: `empty`
    static public var customThumbnailExtensions: [String] = []
+
    
-    static public var imagePropertiesExtensions: [String] = ["jpg", "jpeg", "bmp", "gif", "png", "tif", "tiff"]
-    static public var audioPropertiesExtensions: [String] = ["mp3", "aac", "m4a", "caf"]
-    static public var videoPropertiesExtensions: [String] = ["mp4", "mpg", "3gp", "mov", "avi"]
-    static public var pdfPropertiesExtensions: [String] = ["pdf"]
+    /// Image extensions supportes for properties.
+    ///
+    /// Default: `["jpg", "jpeg", "gif", "bmp", "png", "tif", "tiff"]`
+    static public var imagePropertiesExtensions: [String]   = ["jpg", "jpeg", "bmp", "gif", "png", "tif", "tiff"]
+    
+    /// Audio and music extensions supportes for properties.
+    ///
+    /// Default: `["mp3", "aac", "m4a", "caf"]`
+    static public var audioPropertiesExtensions: [String]   = ["mp3", "aac", "m4a", "caf"]
+    
+    /// Video extensions supportes for properties.
+    ///
+    /// Default: `["mp4", "mpg", "3gp", "mov", "avi"]`
+    static public var videoPropertiesExtensions: [String]   = ["mp4", "mpg", "3gp", "mov", "avi"]
+    
+    /// Portable document file extensions supportes for properties.
+    ///
+    /// Default: `["pdf"]`
+    static public var pdfPropertiesExtensions: [String]     = ["pdf"]
+    
+    /// Archive extensions (like zip) supportes for properties.
+    ///
+    /// Default: `empty`
    static public var archivePropertiesExtensions: [String] = []
-    static public var officePropertiesExtensions: [String] = []
-    static public var customPropertiesExtensions: [String] = []
    
+    /// Office document extensions supportes for properties.
+    ///
+    /// Default: `empty`
+    static public var officePropertiesExtensions: [String]  = []
+    
+    /// Custom document extensions supportes for properties.
+    ///
+    /// Default: `empty`
+    static public var customPropertiesExtensions: [String]  = []
+    
+    /// Thumbnail generator closure for image files.
    static public var imageThumbnail: (_ fileURL: URL) -> ImageClass? = { fileURL in
        return ImageClass(contentsOfFile: fileURL.path)
    }
    
+    /// Thumbnail generator closure for audio and music files.
    static public var audioThumbnail: (_ fileURL: URL) -> ImageClass? = { fileURL in
        let playerItem = AVPlayerItem(url: fileURL)
        let metadataList = playerItem.asset.commonMetadata
@@ -159,6 +207,7 @@ public struct LocalFileInformationGenerator {
        return nil
    }
    
+    /// Thumbnail generator closure for video files.
    static public var videoThumbnail: (_ fileURL: URL) -> ImageClass? = { fileURL in
        let asset = AVAsset(url: fileURL)
        let assetImgGenerate = AVAssetImageGenerator(asset: asset)
@@ -166,7 +215,7 @@ public struct LocalFileInformationGenerator {
        let time = CMTimeMake(asset.duration.value / 3, asset.duration.timescale)
        if let cgImage = try? assetImgGenerate.copyCGImage(at: time, actualTime: nil) {
            #if os(macOS)
-            return ImageClass(cgImage: cgImage, size: NSSize.zero)
+            return ImageClass(cgImage: cgImage, size: .zero)
            #else
            return ImageClass(cgImage: cgImage)
            #endif
@@ -174,20 +223,35 @@ public struct LocalFileInformationGenerator {
        return nil
    }
    
+    /// Thumbnail generator closure for portable document files files.
    static public var pdfThumbnail: (_ fileURL: URL) -> ImageClass? = { fileURL in
-        guard let data = try? Data(contentsOf: fileURL) else { return nil }
-        return LocalFileProvider.convertToImage(pdfData: data)
+        return LocalFileProvider.convertToImage(pdfURL: fileURL)
    }
    
+    /// Thumbnail generator closure for office document files.
+    /// - Note: No default implementation is avaiable
    static public var officeThumbnail: (_ fileURL: URL) -> ImageClass? = { fileURL in
        return nil
    }
    
+    /// Thumbnail generator closure for custom type of files.
+    /// - Note: No default implementation is avaiable
    static public var customThumbnail: (_ fileURL: URL) -> ImageClass? = { fileURL in
        return nil
    }
    
+    /// Properties generator closure for image files.
    static public var imageProperties: ((_ fileURL: URL) -> (prop: [String: Any], keys: [String]))? = { fileURL in
+        var dic = [String: Any]()
+        var keys = [String]()
+        
+        func add(key: String, value: Any?) {
+            if let value = value, !((value as? String)?.isEmpty ?? false) {
+                keys.append(key)
+                dic[key] = value
+            }
+        }
+        
        func simplify(_ top:Int64, _ bottom:Int64) -> (newTop:Int, newBottom:Int) {
            var x = top
            var y = bottom
@@ -202,79 +266,55 @@ public struct LocalFileInformationGenerator {
            return(Int(newTopVal), Int(newBottomVal))
        }
        
-        var dic = [String: Any]()
-        var keys = [String]()
        guard let cgDataRef = CGImageSourceCreateWithURL(fileURL as CFURL, nil), let cfImageDict = CGImageSourceCopyPropertiesAtIndex(cgDataRef, 0, nil) else {
            return (dic, keys)
        }
        let imageDict = cfImageDict as NSDictionary
-        let tiffDict = imageDict[kCGImagePropertyTIFFDictionary as String] as? [String : AnyObject] ?? [:]
-        let exifDict = imageDict[kCGImagePropertyExifDictionary as String] as? [String : AnyObject] ?? [:]
-        if let pixelWidth: AnyObject = imageDict.object(forKey: kCGImagePropertyPixelWidth) as? NSNumber, let pixelHeight: AnyObject = imageDict.object(forKey: kCGImagePropertyPixelHeight) as? NSNumber {
-            keys.append("Dimensions")
-            dic["Dimensions"] = "\(pixelWidth)x\(pixelHeight)"
+        let tiffDict = imageDict[kCGImagePropertyTIFFDictionary as String] as? NSDictionary ?? [:]
+        let exifDict = imageDict[kCGImagePropertyExifDictionary as String] as? NSDictionary ?? [:]
+        if let pixelWidth = imageDict.object(forKey: kCGImagePropertyPixelWidth) as? NSNumber, let pixelHeight = imageDict.object(forKey: kCGImagePropertyPixelHeight) as? NSNumber {
+            add(key: "Dimensions", value: "\(pixelWidth)x\(pixelHeight)")
        }
-        if let dpi = imageDict[kCGImagePropertyDPIWidth as String] {
-            keys.append("DPI")
-            dic["DPI"] = dpi
+        
+        add(key: "DPI", value: imageDict[kCGImagePropertyDPIWidth as String])
+        add(key: "Device make", value: tiffDict[kCGImagePropertyTIFFMake as String])
+        add(key: "Device model", value: tiffDict[kCGImagePropertyTIFFModel as String])
+        add(key: "Lens model", value: exifDict[kCGImagePropertyExifLensModel as String])
+        add(key: "Artist", value: tiffDict[kCGImagePropertyTIFFArtist as String] as? String)
+        add(key: "Copyright", value: tiffDict[kCGImagePropertyTIFFCopyright as String] as? String)
+        add(key: "Date taken", value: tiffDict[kCGImagePropertyTIFFDateTime as String] as? String)
+        
+        if let latitude = tiffDict[kCGImagePropertyGPSLatitude as String] as? NSNumber, let longitude = tiffDict[kCGImagePropertyGPSLongitude as String] as? NSNumber {
+            add(key: "Location", value: "\(latitude), \(longitude)")
        }
-        if let devicemake = tiffDict[kCGImagePropertyTIFFMake as String] {
-            keys.append("Device make")
-            dic["Device make"] = devicemake
-        }
-        if let devicemodel = tiffDict[kCGImagePropertyTIFFModel as String] {
-            keys.append("Device model")
-            dic["Device model"] = devicemodel
-        }
-        if let lensmodel = exifDict[kCGImagePropertyExifLensModel as String] {
-            keys.append("Lens model")
-            dic["Lens model"] = lensmodel
-        }
-        if let artist = tiffDict[kCGImagePropertyTIFFArtist as String] as? String , !artist.isEmpty {
-            keys.append("Artist")
-            dic["Artist"] = artist
-        }
-        if let cr = tiffDict[kCGImagePropertyTIFFCopyright as String] as? String , !cr.isEmpty {
-            keys.append("Copyright")
-            dic["Copyright"] = cr
-        }
-        if let date = tiffDict[kCGImagePropertyTIFFDateTime as String] as? String , !date.isEmpty {
-            keys.append("Date taken")
-            dic["Date taken"] = date
-        }
-        if let latitude = tiffDict[kCGImagePropertyGPSLatitude as String]?.doubleValue, let longitude = tiffDict[kCGImagePropertyGPSLongitude as String]?.doubleValue {
-            keys.append("Location")
-            dic["Location"] = "\(latitude), \(longitude)"
-        }
-        if let colorspace = imageDict[kCGImagePropertyColorModel as String] {
-            keys.append("Color space")
-            dic["Color space"] = colorspace
-        }
-        if let focallen = exifDict[kCGImagePropertyExifFocalLength as String] {
-            keys.append("Focal length")
-            dic["Focal length"] = focallen
-        }
-        if let fnum = exifDict[kCGImagePropertyExifFNumber as String] {
-            keys.append("F number")
-            dic["F number"] = fnum
-        }
-        if let expprog = exifDict[kCGImagePropertyExifExposureProgram as String] {
-            keys.append("Exposure program")
-            dic["Exposure program"] = expprog
-        }
-        if let exp = exifDict[kCGImagePropertyExifExposureTime as String]?.doubleValue {
-            let expfrac = simplify(Int64(exp * 10_000_000_000_000), 10_000_000_000_000)
-            keys.append("Exposure time")
-            dic["Exposure time"] = "\(expfrac.newTop)/\(expfrac.newBottom)"
-        }
-        if let iso = exifDict[kCGImagePropertyExifISOSpeedRatings as String] as? NSArray , iso.count > 0 {
-            keys.append("ISO speed")
-            dic["ISO speed"] = iso[0]
+        add(key: "Altitude", value: tiffDict[kCGImagePropertyGPSAltitude as String] as? NSNumber)
+        add(key: "Area", value: tiffDict[kCGImagePropertyGPSAreaInformation as String])
+        
+        add(key: "Color space", value: imageDict[kCGImagePropertyColorModel as String])
+        add(key: "Focal length", value: exifDict[kCGImagePropertyExifFocalLength as String])
+        add(key: "F number", value: exifDict[kCGImagePropertyExifFNumber as String])
+        add(key: "Exposure program", value: exifDict[kCGImagePropertyExifExposureProgram as String])
+        
+        if let exp = exifDict[kCGImagePropertyExifExposureTime as String] as? NSNumber {
+            let expfrac = simplify(Int64(exp.doubleValue * 1_163_962_800_000), 1_163_962_800_000)
+            add(key: "Exposure time", value: "\(expfrac.newTop)/\(expfrac.newBottom)")
        }
+        add(key: "ISO speed", value: (exifDict[kCGImagePropertyExifISOSpeedRatings as String] as? [NSNumber])?.first)
        return (dic, keys)
    }
    
+    /// Properties generator closure for audio and music files.
    static var audioProperties: ((_ fileURL: URL) -> (prop: [String: Any], keys: [String]))? = { fileURL in
+        var dic = [String: Any]()
+        var keys = [String]()
+        
+        func add(key: String, value: Any?) {
+            if let value = value {
+                keys.append(key)
+                dic[key] = value
+            }
+        }
+        
        func makeDescription(_ key: String?) -> String? {
            guard let key = key else {
                return nil
@@ -286,8 +326,6 @@ public struct LocalFileInformationGenerator {
            return newKey.capitalized
        }
        
-        var dic = [String: Any]()
-        var keys = [String]()
        if FileManager.default.fileExists(atPath: fileURL.path) {
            let playerItem = AVPlayerItem(url: fileURL)
            let metadataList = playerItem.asset.commonMetadata
@@ -300,20 +338,25 @@ public struct LocalFileInformationGenerator {
                }
            }
            if let ap = try? AVAudioPlayer(contentsOf: fileURL) {
-                keys.append("Duration")
-                dic["Duration"] = LocalFileProvider.formatshort(interval: ap.duration)
-                if let bitRate = ap.settings[AVSampleRateKey] as? Int {
-                    keys.append("Bitrate")
-                    dic["Bitrate"] = bitRate
-                }
+                add(key: "Duration", value: ap.duration.formatshort)
+                add(key: "Bitrate", value: ap.settings[AVSampleRateKey] as? Int)
            }
        }
        return (dic, keys)
    }
    
+    /// Properties generator closure for video files.
    static public var videoProperties: ((_ fileURL: URL) -> (prop: [String: Any], keys: [String]))? = { fileURL in
        var dic = [String: Any]()
        var keys = [String]()
+        
+        func add(key: String, value: Any?) {
+            if let value = value {
+                keys.append(key)
+                dic[key] = value
+            }
+        }
+        
        if let audioprops = LocalFileInformationGenerator.audioProperties?(fileURL) {
            dic = audioprops.prop
            keys = audioprops.keys
@@ -324,21 +367,18 @@ public struct LocalFileInformationGenerator {
        }
        let asset = AVURLAsset(url: fileURL, options: nil)
        let videoTracks = asset.tracks(withMediaType: AVMediaTypeVideo)
-        if videoTracks.count > 0 {
+        if let videoTrack = videoTracks.first {
            var bitrate: Float = 0
-            let width = Int(videoTracks[0].naturalSize.width)
-            let height = Int(videoTracks[0].naturalSize.height)
-            keys.append("Dimensions")
-            dic["Dimensions"] = "\(width)x\(height)"
+            let width = Int(videoTrack.naturalSize.width)
+            let height = Int(videoTrack.naturalSize.height)
+            add(key: "Dimensions", value: "\(width)x\(height)")
            var duration: Int64 = 0
            for track in videoTracks {
                duration += track.timeRange.duration.timescale > 0 ? track.timeRange.duration.value / Int64(track.timeRange.duration.timescale) : 0
                bitrate += track.estimatedDataRate
            }
-            keys.append("Duration")
-            dic["Duration"] = LocalFileProvider.formatshort(interval: TimeInterval(duration))
-            keys.append("Video Bitrate")
-            dic["Video Bitrate"] = "\(Int(ceil(bitrate / 1000))) kbps"
+            add(key: "Duration", value: TimeInterval(duration).formatshort)
+            add(key: "Video Bitrate", value: "\(Int(ceil(bitrate / 1000))) kbps")
        }
        let audioTracks = asset.tracks(withMediaType: AVMediaTypeAudio)
        // dic["Audio channels"] = audioTracks.count
@@ -346,12 +386,22 @@ public struct LocalFileInformationGenerator {
        for track in audioTracks {
            bitrate += track.estimatedDataRate
        }
-        keys.append("Audio Bitrate")
-        dic["Audio Bitrate"] = "\(Int(ceil(bitrate / 1000))) kbps"
+        add(key: "Audio Bitrate", value: "\(Int(ceil(bitrate / 1000))) kbps")
        return (dic, keys)
    }
    
+    /// Properties generator closure for protable documents files.
    static public var pdfProperties: ((_ fileURL: URL) -> (prop: [String: Any], keys: [String]))? = { fileURL in
+        var dic = [String: Any]()
+        var keys = [String]()
+        
+        func add(key: String, value: Any?) {
+            if let value = value, !((value as? String)?.isEmpty ?? false) {
+                keys.append(key)
+                dic[key] = value
+            }
+        }
+        
        func getKey(_ key: String, from dict: CGPDFDictionaryRef) -> String? {
            var cfValue: CGPDFStringRef? = nil
            if (CGPDFDictionaryGetString(dict, key, &cfValue)), let value = CGPDFStringCopyTextString(cfValue!) {
@@ -360,10 +410,11 @@ public struct LocalFileInformationGenerator {
            return nil
        }
        
-        func convertDate(_ date: String) -> Date? {
+        func convertDate(_ date: String?) -> Date? {
+            guard let date = date else { return nil }
            var dateStr = date
            if dateStr.hasPrefix("D:") {
-                dateStr = date.substring(from: date.characters.index(date.startIndex, offsetBy: 2))
+                dateStr.characters.removeFirst(2)
            }
            let dateFormatter = DateFormatter()
            dateFormatter.dateFormat = "yyyyMMddHHmmssTZD"
@@ -377,67 +428,45 @@ public struct LocalFileInformationGenerator {
            return nil
        }
        
-        var dic = [String: Any]()
-        var keys = [String]()
-        if let data = try? Data(contentsOf: fileURL), let provider = CGDataProvider(data: data as CFData), let reference = CGPDFDocument(provider), let dict = reference.info {
-            if let title = getKey("Title", from: dict), !title.isEmpty {
-                keys.append("Title")
-                dic["Title"] = title
-            }
-            if let author = getKey("Author", from: dict), !author.isEmpty {
-                keys.append("Author")
-                dic["Author"] = author
-            }
-            if let subject = getKey("Subject", from: dict), !subject.isEmpty {
-                keys.append("Subject")
-                dic["Subject"] = subject
-            }
+        if let provider = CGDataProvider(url: fileURL as CFURL), let reference = CGPDFDocument(provider), let dict = reference.info {
+            add(key: "Title", value: getKey("Title", from: dict))
+            add(key: "Author", value: getKey("Author", from: dict))
+            add(key: "Subject", value: getKey("Subject", from: dict))
            var majorVersion: Int32 = 0
            var minorVersion: Int32 = 0
            reference.getVersion(majorVersion: &majorVersion, minorVersion: &minorVersion)
            if majorVersion > 0 {
-                keys.append("Version")
-                dic["Version"] = String(majorVersion) + "." + String(minorVersion)
-            }
-            if reference.numberOfPages > 0 {
-                keys.append("Pages")
-                dic["Pages"] = reference.numberOfPages
+                add(key: "Version", value:  String(majorVersion) + "." + String(minorVersion))
            }
+            add(key: "Pages", value: reference.numberOfPages)
            
            if reference.numberOfPages > 0, let pageRef = reference.page(at: 1) {
                let size = pageRef.getBoxRect(CGPDFBox.mediaBox).size
-                keys.append("Resolution")
-                dic["Resolution"] = "\(Int(size.width))x\(Int(size.height))"
+                add(key: "Resolution", value: "\(Int(size.width))x\(Int(size.height))")
            }
-            if let creator = getKey("Creator", from: dict), !creator.isEmpty {
-                keys.append("Content creator")
-                dic["Content creator"] = creator
-            }
-            if let creationDateString = getKey("CreationDate", from: dict), let creationDate = convertDate(creationDateString) {
-                keys.append("Creation date")
-                dic["Creation date"] = creationDate
-            }
-            if let modifiedDateString = getKey("ModDate", from: dict), let modDate = convertDate(modifiedDateString) {
-                keys.append("Modified date")
-                dic["Modified date"] = modDate
-            }
-            keys.append("Security")
-            dic["Security"] = reference.isEncrypted ? "Present" : "None"
-            keys.append("Allows printing")
-            dic["Allows printing"] = reference.allowsPrinting ? "Yes" : "No"
-            keys.append("Allows copying")
-            dic["Allows copying"] = reference.allowsCopying ? "Yes" : "No"
+            add(key: "Content creator", value: getKey("Creator", from: dict))
+            add(key: "Creation date", value: convertDate(getKey("CreationDate", from: dict)))
+            add(key: "Modified date", value: convertDate(getKey("ModDate", from: dict)))
+            add(key: "Security", value: reference.isEncrypted ? "Present" : "None")
+            add(key: "Allows printing", value: reference.allowsPrinting ? "Yes" : "No")
+            add(key: "Allows copying", value: reference.allowsCopying ? "Yes" : "No")
        }
        return (dic, keys)
    }
    
+    /// Properties generator closure for video files.
+    /// - Note: No default implementation is avaiable
    static public var archiveProperties: ((_ fileURL: URL) -> (prop: [String: Any], keys: [String]))? = nil
    
+    /// Properties generator closure for office doument files.
+    /// - Note: No default implementation is avaiable
    static public var officeProperties: ((_ fileURL: URL) -> (prop: [String: Any], keys: [String]))? = nil
    
+    /// Properties generator closure for custom type of files.
+    /// - Note: No default implementation is avaiable
    static public var customProperties: ((_ fileURL: URL) -> (prop: [String: Any], keys: [String]))? = nil
 }

-func ~=<T : Equatable>(array: [T], value: T) -> Bool {
+fileprivate func ~=<T : Equatable>(array: [T], value: T) -> Bool {
    return array.contains(value)
 }
@@ -12,52 +12,106 @@ private var lasttaskIdAssociated = 1_000_000_000


 /// This class is a replica of NSURLSessionStreamTask with same api for iOS 7/8
-/// while it will fallback to NSURLSessionStreamTask in iOS 9.
-@objc
-open class FPSStreamTask: URLSessionTask, StreamDelegate {
+/// while it can actually fallback to NSURLSessionStreamTask in iOS 9.
+public class FileProviderStreamTask: URLSessionTask, StreamDelegate {
    fileprivate var inputStream: InputStream?
    fileprivate var outputStream: OutputStream?
    
-    fileprivate var dispatch_queue: DispatchQueue!
+    fileprivate var operation_queue: OperationQueue!
    internal var _underlyingSession: URLSession
    fileprivate var streamDelegate: FPSStreamDelegate? {
        return (_underlyingSession.delegate as? FPSStreamDelegate)
    }
    fileprivate var _taskIdentifier: Int
+    fileprivate var _taskDescription: String?
    
+    /// Force using `URLSessionStreamTask` for iOS 9 and later
+    public var useURLSession = true
    @available(iOS 9.0, OSX 10.11, *)
-    static var streamTasks = [Int: URLSessionStreamTask]()
+    fileprivate static var streamTasks = [Int: URLSessionStreamTask]()
    
    @available(iOS 9.0, OSX 10.11, *)
    internal var _underlyingTask: URLSessionStreamTask? {
-        return FPSStreamTask.streamTasks[_taskIdentifier]
+        return FileProviderStreamTask.streamTasks[_taskIdentifier]
    }
    
+    /**
+     * An identifier uniquely identifies the task within a given session.
+     *
+     * This value is unique only within the context of a single session; 
+     * tasks in other sessions may have the same `taskIdentifier` value.
+     */
    open override var taskIdentifier: Int {
        if #available(iOS 9.0, OSX 10.11, *) {
-            return _underlyingTask!.taskIdentifier
-        } else {
-            return _taskIdentifier
+            if self.useURLSession {
+                return _underlyingTask!.taskIdentifier
+            }
+        }
+        
+        return _taskIdentifier
+    }
+    
+    /// An app-provided description of the current task.
+    ///
+    /// This value may be nil. It is intended to contain human-readable strings that you can
+    /// then display to the user as part of your app’s user interface.
+    open override var taskDescription: String? {
+        get {
+            if #available(iOS 9.0, OSX 10.11, *) {
+                if self.useURLSession {
+                    return _underlyingTask!.taskDescription
+                }
+            }
+            
+            return _taskDescription
+        }
+        set {
+            if #available(iOS 9.0, OSX 10.11, *) {
+                if self.useURLSession {
+                    _underlyingTask!.taskDescription = newValue
+                    return
+                }
+            }
+            
+            _taskDescription = newValue
        }
    }
    
    fileprivate var _state: URLSessionTask.State = .suspended
+    /**
+     * The current state of the task—active, suspended, in the process 
+     * of being canceled, or completed.
+    */
    override open var state: URLSessionTask.State {
        if #available(iOS 9.0, OSX 10.11, *) {
-            return _underlyingTask!.state
-        } else {
-            return _state
+            if self.useURLSession {
+                return _underlyingTask!.state
+            }
        }
+        
+        return _state
    }
    
+    /**
+     * The original request object passed when the task was created.
+     * This value is typically the same as the currently active request (`currentRequest`)
+     * except when the server has responded to the initial request with a redirect to a different URL.
+    */
    override open var originalRequest: URLRequest? {
        if #available(iOS 9.0, OSX 10.11, *) {
-            return _underlyingTask!.originalRequest
-        } else {
-            return nil
+            if self.useURLSession {
+                return _underlyingTask!.originalRequest
+            }
        }
+        
+        return nil
    }
    
+    /**
+     * The URL request object currently being handled by the task.
+     * This value is typically the same as the initial request (`originalRequest`)
+     * except when the server has responded to the initial request with a redirect to a different URL.
+    */
    override open var currentRequest: URLRequest? {
        if #available(iOS 9.0, OSX 10.11, *) {
            return _underlyingTask!.currentRequest
@@ -69,441 +123,552 @@ open class FPSStreamTask: URLSessionTask, StreamDelegate {
    fileprivate var _countOfBytesSent: Int64 = 0
    fileprivate var _countOfBytesRecieved: Int64 = 0
    
+    /**
+     * The number of bytes that the task has sent to the server in the request body.
+     *
+     * This byte count includes only the length of the request body itself, not the request headers.
+     *
+     * To be notified when this value changes, implement the 
+     * `urlSession(_:task:didSendBodyData:totalBytesSent:totalBytesExpectedToSend:)` delegate method.
+    */
    override open var countOfBytesSent: Int64 {
        if #available(iOS 9.0, OSX 10.11, *) {
-            return _underlyingTask!.countOfBytesSent
-        } else {
-            return _countOfBytesSent
+            if self.useURLSession {
+                return _underlyingTask!.countOfBytesSent
+            }
        }
+        
+        return _countOfBytesSent
    }
    
+    /**
+     * The number of bytes that the task has received from the server in the response body.
+     *
+     * To be notified when this value changes, implement the `urlSession(_:dataTask:didReceive:)` delegate method (for data and upload tasks)
+     * or the `urlSession(_:downloadTask:didWriteData:totalBytesWritten:totalBytesExpectedToWrite:)` method (for download tasks).
+    */
    override open var countOfBytesReceived: Int64 {
        if #available(iOS 9.0, OSX 10.11, *) {
-            return _underlyingTask!.countOfBytesReceived
-        } else {
-            return _countOfBytesRecieved
+            if self.useURLSession {
+                return _underlyingTask!.countOfBytesReceived
+            }
        }
+        
+        return _countOfBytesRecieved
    }
    
+    /**
+     * The number of bytes that the task expects to send in the request body.
+     *
+     * The `URL` loading system can determine the length of the upload data in three ways:
+     * - From the length of the `NSData` object provided as the upload body.
+     * - From the length of the file on disk provided as the upload body of an upload task (not a download task).
+     * - From the `Content-Length` in the request object, if you explicitly set it.
+     *
+     * Otherwise, the value is `NSURLSessionTransferSizeUnknown` (`-1`) if you provided a stream or body data object, or zero (`0`) if you did not.
+    */
    override open var countOfBytesExpectedToSend: Int64 {
        if #available(iOS 9.0, OSX 10.11, *) {
            return _underlyingTask!.countOfBytesExpectedToSend
        } else {
-            return Int64(dataToBeSent.length)
+            return Int64(dataToBeSent.count)
        }
    }
    
+    /**
+     * The number of bytes that the task expects to receive in the response body.
+     *
+     * This value is determined based on the `Content-Length` header received from the server.
+     * If that header is absent, the value is `NSURLSessionTransferSizeUnknown`.
+    */
    override open var countOfBytesExpectedToReceive: Int64 {
        if #available(iOS 9.0, OSX 10.11, *) {
-            return _underlyingTask!.countOfBytesExpectedToReceive
-        } else {
-            return Int64(dataReceived.length)
+            if self.useURLSession {
+                return _underlyingTask!.countOfBytesExpectedToReceive
+            }
        }
+        
+        return Int64(dataReceived.count)
    }
    
    override public init() {
        fatalError("Use NSURLSession.fpstreamTask() method")
    }
    
-    var host: (hostname: String, port: Int)?
-    var service: NetService?
+    fileprivate var host: (hostname: String, port: Int)?
+    fileprivate var service: NetService?
    
    internal init(session: URLSession, host: String, port: Int) {
        self._underlyingSession = session
        if #available(iOS 9.0, OSX 10.11, *) {
-            let task = session.streamTask(withHostName: host, port: port)
-            self._taskIdentifier = task.taskIdentifier
-            FPSStreamTask.streamTasks[_taskIdentifier] = task
-        } else {
-            lasttaskIdAssociated += 1
-            self._taskIdentifier = lasttaskIdAssociated
-            self.host = (host, port)
-            self.dispatch_queue = DispatchQueue(label: "FSPStreamTask", attributes: DispatchQueue.Attributes.concurrent)
+            if self.useURLSession {
+                let task = session.streamTask(withHostName: host, port: port)
+                self._taskIdentifier = task.taskIdentifier
+                FileProviderStreamTask.streamTasks[_taskIdentifier] = task
+                return
+            }
        }
+        
+        lasttaskIdAssociated += 1
+        self._taskIdentifier = lasttaskIdAssociated
+        self.host = (host, port)
+        self.operation_queue = OperationQueue()
+        self.operation_queue.name = "FileProviderStreamTask"
+        self.operation_queue.maxConcurrentOperationCount = 1
    }
    
    internal init(session: URLSession, netService: NetService) {
        self._underlyingSession = session
        if #available(iOS 9.0, OSX 10.11, *) {
-            let task = session.streamTask(with: netService)
-            self._taskIdentifier = task.taskIdentifier
-            FPSStreamTask.streamTasks[_taskIdentifier] = task
-        } else {
-            lasttaskIdAssociated += 1
-            self._taskIdentifier = lasttaskIdAssociated
-            self.service = netService
-            self.dispatch_queue = DispatchQueue(label: "FSPStreamTask", attributes: DispatchQueue.Attributes.concurrent)
+            if self.useURLSession {
+                let task = session.streamTask(with: netService)
+                self._taskIdentifier = task.taskIdentifier
+                FileProviderStreamTask.streamTasks[_taskIdentifier] = task
+                return
+            }
        }
+        
+        lasttaskIdAssociated += 1
+        self._taskIdentifier = lasttaskIdAssociated
+        self.service = netService
+        self.operation_queue = OperationQueue()
+        self.operation_queue.name = "FileProviderStreamTask"
+        self.operation_queue.maxConcurrentOperationCount = 1
    }
    
+    /**
+     * Cancels the task.
+     *
+     * This method returns immediately, marking the task as being canceled. Once a task is marked as being canceled, 
+     * `urlSession(_:task:didCompleteWithError:)` will be sent to the task delegate, passing an error
+     * in the domain NSURLErrorDomain with the code `NSURLErrorCancelled`. A task may, under some circumstances,
+     * send messages to its delegate before the cancelation is acknowledged.
+     *
+     * This method may be called on a task that is suspended.
+    */
    override open func cancel() {
        if #available(iOS 9.0, OSX 10.11, *) {
-            _underlyingTask!.cancel()
-        } else {
-            self._state = .canceling
-            inputStream?.setValue(kCFBooleanTrue, forKey: kCFStreamPropertyShouldCloseNativeSocket as String)
-            outputStream?.setValue(kCFBooleanTrue, forKey: kCFStreamPropertyShouldCloseNativeSocket as String)
-            
-            self.inputStream?.close()
-            self.outputStream?.close()
-            
-            self.inputStream?.remove(from: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
-            self.outputStream?.remove(from: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
-            
-            self.inputStream?.delegate = nil
-            self.outputStream?.delegate = nil
-            
-            self.inputStream = nil
-            self.outputStream = nil
-            
-            self._state = .completed
-            self._countOfBytesSent = 0
-            self._countOfBytesRecieved = 0
+            if self.useURLSession {
+                _underlyingTask!.cancel()
+                return
+            }
        }
+        
+        self._state = .canceling
+        inputStream?.setValue(kCFBooleanTrue, forKey: kCFStreamPropertyShouldCloseNativeSocket as String)
+        outputStream?.setValue(kCFBooleanTrue, forKey: kCFStreamPropertyShouldCloseNativeSocket as String)
+        
+        self.inputStream?.close()
+        self.outputStream?.close()
+        
+        self.inputStream?.remove(from: RunLoop.main, forMode: .defaultRunLoopMode)
+        self.outputStream?.remove(from: RunLoop.main, forMode: .defaultRunLoopMode)
+        
+        self.inputStream?.delegate = nil
+        self.outputStream?.delegate = nil
+        
+        self.inputStream = nil
+        self.outputStream = nil
+        
+        self._state = .completed
+        self._countOfBytesSent = 0
+        self._countOfBytesRecieved = 0
    }
    
    var _error: Error? = nil
+    
+    /**
+     * An error object that indicates why the task failed.
+     *
+     * This value is `NULL` if the task is still active or if the transfer completed successfully.
+    */
    override open var error: Error? {
        if #available(iOS 9.0, OSX 10.11, *) {
-            return _underlyingTask!.error
-        } else {
-            return _error
+            if useURLSession {
+                return _underlyingTask!.error
+            }
        }
+        
+        return _error
    }
    
+    /**
+     * Temporarily suspends a task.
+     *
+     * A task, while suspended, produces no network traffic and is not subject to timeouts. 
+     * A download task can continue transferring data at a later time. 
+     * All other tasks must start over when resumed.
+    */
    override open func suspend() {
        if #available(iOS 9.0, OSX 10.11, *) {
-            _underlyingTask!.suspend()
-        } else {
-            self._state = .suspended
+            if self.useURLSession {
+                _underlyingTask!.suspend()
+                return
+            }
        }
+        
+        self._state = .suspended
+        self.operation_queue.isSuspended = true
    }
    
+    // Resumes the task, if it is suspended.
    override open func resume() {
        if #available(iOS 9.0, OSX 10.11, *) {
-            _underlyingTask!.resume()
-        } else {
-            var readStream : Unmanaged<CFReadStream>?
-            var writeStream : Unmanaged<CFWriteStream>?
-            
-            if inputStream == nil || outputStream == nil {
-                if let host = host {
-                    let hostRef: CFString = NSString(string: host.hostname)
-                    CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, hostRef, UInt32(host.port), &readStream, &writeStream)
-                } else if let service = service {
-                    let cfnetService = CFNetServiceCreate(kCFAllocatorDefault, service.domain as CFString, service.type as CFString, service.name as CFString, Int32(service.port))
-                    CFStreamCreatePairWithSocketToNetService(kCFAllocatorDefault, cfnetService.takeRetainedValue(), &readStream, &writeStream)
-                }
-                
-                inputStream = readStream?.takeRetainedValue()
-                outputStream = writeStream?.takeRetainedValue()
-                guard let inputStream = inputStream, let outputStream = outputStream else {
-                    return
-                }
-                streamDelegate?.urlSession?(self._underlyingSession, streamTask: self, didBecome: inputStream, outputStream: outputStream)
+            if self.useURLSession {
+                _underlyingTask!.resume()
+                return
+            }
+        }
+        
+        var readStream : Unmanaged<CFReadStream>?
+        var writeStream : Unmanaged<CFWriteStream>?
+        
+        if inputStream == nil || outputStream == nil {
+            if let host = host {
+                CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, host.hostname as CFString, UInt32(host.port), &readStream, &writeStream)
+            } else if let service = service {
+                let cfnetService = CFNetServiceCreate(kCFAllocatorDefault, service.domain as CFString, service.type as CFString, service.name as CFString, Int32(service.port))
+                CFStreamCreatePairWithSocketToNetService(kCFAllocatorDefault, cfnetService.takeRetainedValue(), &readStream, &writeStream)
            }
            
+            inputStream = readStream?.takeRetainedValue()
+            outputStream = writeStream?.takeRetainedValue()
            guard let inputStream = inputStream, let outputStream = outputStream else {
                return
            }
-            
-            inputStream.delegate = self
-            outputStream.delegate = self
-            
-            dispatch_queue.sync(execute: { 
-                inputStream.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
-                outputStream.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
-            })
-            
-            inputStream.open()
-            outputStream.open()
-            
-            _state = .running
+            streamDelegate?.urlSession?(self._underlyingSession, streamTask: self, didBecome: inputStream, outputStream: outputStream)
        }
-    }
-    
-    fileprivate let dataToBeSent: NSMutableData = NSMutableData()
-    fileprivate let dataReceived: NSMutableData = NSMutableData()
-    
-    /* Read minBytes, or at most maxBytes bytes and invoke the completion
-     * handler on the sessions delegate queue with the data or an error.
-     * If an error occurs, any outstanding reads will also fail, and new
-     * read requests will error out immediately.
-     */
-    open func readData(OfMinLength minBytes: Int, maxLength maxBytes: Int, timeout: TimeInterval, completionHandler: @escaping (Data?, Bool, NSError?) -> Void) {
-        if #available(iOS 9.0, OSX 10.11, *) {
-            _underlyingTask!.readData(ofMinLength: minBytes, maxLength: maxBytes, timeout: timeout, completionHandler: completionHandler as! (Data?, Bool, Error?) -> Void)
-        } else {
-            guard let inputStream = inputStream else {
-                return
-            }
-            var timedOut: Bool = false
-            dispatch_queue.async {
-                if timeout > 0 {
-                    self.dispatch_queue.asyncAfter(deadline: DispatchTime.now() + Double(Int64(timeout * 1_000_000_000)) / Double(NSEC_PER_SEC), execute: {
-                        timedOut = true
-                        completionHandler(nil, inputStream.streamStatus == .atEnd, inputStream.streamError as NSError?)
-                    })
-                }
-                while (self.dataReceived.length == 0 || self.dataReceived.length < minBytes) && !timedOut {
-                    RunLoop.current.run(until: Date(timeIntervalSinceNow: 0.1));
-                    Thread.sleep(forTimeInterval: 0.1)
-                }
-                let dR = NSMutableData()
-                if self.dataReceived.length > maxBytes {
-                    let range = NSRange(location: 0, length: maxBytes - 1)
-                    dR.append(self.dataReceived.subdata(with: range))
-                    self.dataReceived.replaceBytes(in: range, withBytes: nil, length: 0)
-                } else {
-                    dR.append(self.dataReceived as Data)
-                    self.dataReceived.length = 0
-                }
-                completionHandler(dR as Data, inputStream.streamStatus == .atEnd, inputStream.streamError as NSError?)
-            }
-        }
-    }
-    
-    /* Write the data completely to the underlying socket.  If all the
-     * bytes have not been written by the timeout, a timeout error will
-     * occur.  Note that invocation of the completion handler does not
-     * guarantee that the remote side has received all the bytes, only
-     * that they have been written to the kernel. */
-    open func writeData(_ data: Data, timeout: TimeInterval, completionHandler: @escaping (Error?) -> Void) {
-        if #available(iOS 9.0, OSX 10.11, *) {
-            _underlyingTask!.write(data, timeout: timeout, completionHandler: completionHandler)
-        } else {
-            guard let outputStream = outputStream else {
-                return
-            }
-            var timedOut: Bool = false
-            dispatch_queue.async {
-                if timeout > 0 {
-                    self.dispatch_queue.asyncAfter(deadline: DispatchTime.now() + Double(Int64(timeout * 1_000_000_000)) / Double(NSEC_PER_SEC), execute: {
-                        timedOut = true
-                        completionHandler(self._error)
-                    })
-                }
-                
-                self.dataToBeSent.append(data)
-                while !outputStream.hasSpaceAvailable && !timedOut {
-                    RunLoop.current.run(until: Date(timeIntervalSinceNow: 0.1));
-                    Thread.sleep(forTimeInterval: 0.1)
-                }
-                if self.dataToBeSent.length > 0 {
-                    let bytesWritten = outputStream.write(self.dataToBeSent.bytes.bindMemory(to: UInt8.self, capacity: self.dataToBeSent.length), maxLength: self.dataToBeSent.length) 
-                    if bytesWritten > 0 {
-                        let range = NSRange(location: 0, length: bytesWritten)
-                        self.dataToBeSent.replaceBytes(in: range, withBytes: nil, length: 0)
-                        self._countOfBytesSent += bytesWritten
-                        completionHandler(nil)
-                    } else {
-                        self._error = outputStream.streamError
-                        completionHandler(outputStream.streamError)
-                    }
-                }
-            }
-        }
-    }
-    
-    /* -captureStreams completes any already enqueued reads
-     * and writes, and then invokes the
-     * URLSession:streamTask:didBecomeInputStream:outputStream: delegate
-     * message. When that message is received, the task object is
-     * considered completed and will not receive any more delegate
-     * messages. */
-    open func captureStreams() {
-        if #available(iOS 9.0, OSX 10.11, *) {
-            _underlyingTask!.captureStreams()
-        } else {
-            guard let outputStream = outputStream, let inputStream = inputStream else {
-                return
-            }
-            dispatch_queue.async {
-                self.write(false)
-                while inputStream.streamStatus != .atEnd {
-                    RunLoop.current.run(until: Date(timeIntervalSinceNow: 0.1));
-                    Thread.sleep(forTimeInterval: 0.1)
-                }
-                self.streamDelegate?.urlSession?(self._underlyingSession, streamTask: self, didBecome: inputStream, outputStream: outputStream)
-            }
-        }
-    }
-    
-    /* Enqueue a request to close the write end of the underlying socket.
-     * All outstanding IO will complete before the write side of the
-     * socket is closed.  The server, however, may continue to write bytes
-     * back to the client, so best practice is to continue reading from
-     * the server until you receive EOF.
-     */
-    open func closeWrite() {
-        if #available(iOS 9.0, OSX 10.11, *) {
-            _underlyingTask!.closeWrite()
-        } else {
-            dispatch_queue.async(execute: { 
-                self.write(true)
-            })
-        }
-    }
-    
-    fileprivate func write(_ close: Bool) {
-        guard let outputStream = outputStream else {
+        
+        guard let inputStream = inputStream, let outputStream = outputStream else {
            return
        }
-        while self.dataToBeSent.length > 0 {
-            let bytesWritten = outputStream.write(self.dataToBeSent.bytes.bindMemory(to: UInt8.self, capacity: self.dataToBeSent.length), maxLength: self.dataToBeSent.length) 
-            if bytesWritten > 0 {
-                let range = NSRange(location: 0, length: bytesWritten)
-                self.dataToBeSent.replaceBytes(in: range, withBytes: nil, length: 0)
-                self._countOfBytesSent += bytesWritten
-            } else {
-                self._error = outputStream.streamError as NSError?
+        
+        inputStream.delegate = self
+        outputStream.delegate = self
+        
+        operation_queue.addOperation {
+            inputStream.schedule(in: RunLoop.main, forMode: .defaultRunLoopMode)
+            outputStream.schedule(in: RunLoop.main, forMode: .defaultRunLoopMode)
+        }
+        
+        inputStream.open()
+        outputStream.open()
+        
+        operation_queue.isSuspended = false
+        _state = .running
+    }
+    
+    fileprivate var dataToBeSent: Data = Data()
+    fileprivate var dataReceived: Data = Data()
+    
+    /**
+     * Asynchronously reads a number of bytes from the stream, and calls a handler upon completion.
+     *
+     * - Parameter minBytes: The minimum number of bytes to read.
+     * - ParametermaxBytes: The maximum number of bytes to read.
+     * - Parameter timeout:  A timeout for reading bytes. If the read is not completed within the specified interval,
+     *        the read is canceled and the completionHandler is called with an error. Pass `0` to prevent a read from timing out.
+     * - Parameter completionHandler: The completion handler to call when all bytes are read, or an error occurs.
+     *        This handler is executed on the delegate queue. This completion handler takes the following parameters:
+     *     - data: The data read from the stream.
+     *     - atEOF: Whether or not the stream reached end-of-file (`EOF`), such that no more data can be read.
+     *     - error: An error object that indicates why the read failed, or `nil` if the read was successful.
+    */
+    open func readData(ofMinLength minBytes: Int, maxLength maxBytes: Int, timeout: TimeInterval, completionHandler: @escaping (_ data: Data?, _ atEOF: Bool, _ error :Error?) -> Void) {
+        if #available(iOS 9.0, OSX 10.11, *) {
+            if self.useURLSession {
+                _underlyingTask!.readData(ofMinLength: minBytes, maxLength: maxBytes, timeout: timeout, completionHandler: completionHandler)
+                return
            }
-            if self.dataToBeSent.length == 0 {
+        }
+        
+        guard let inputStream = inputStream else {
+            return
+        }
+        
+        let expireDate = Date(timeIntervalSinceNow: timeout)
+        operation_queue.addOperation {
+            var timedOut: Bool = false
+            while (self.dataReceived.count == 0 || self.dataReceived.count < minBytes) && !timedOut {
+                Thread.sleep(forTimeInterval: 0.1)
+                timedOut = expireDate < Date()
+            }
+            var dR: Data?
+            if self.dataReceived.count > maxBytes {
+                let range: Range = 0..<maxBytes
+                dR = self.dataReceived.subdata(in: range)
+                self.dataReceived.replaceSubrange(range, with: Data())
+            } else {
+                if self.dataReceived.count > 0 {
+                    dR = self.dataReceived
+                    self.dataReceived.count = 0
+                }
+            }
+            let isEOF = inputStream.streamStatus == .atEnd && self.dataReceived.count == 0
+            completionHandler(dR, isEOF, dR == nil ? inputStream.streamError : nil)
+        }
+    }
+    
+    /**
+     * Asynchronously writes the specified data to the stream, and calls a handler upon completion.
+     *
+     * There is no guarantee that the remote side of the stream has received all of the written bytes
+     * at the time that `completionHandler` is called, only that all of the data has been written to the kernel.
+     *
+     * - Parameter data: The data to be written.
+     * - Parameter timeout: A timeout for writing bytes. If the write is not completed within the specified interval,
+     *      the write is canceled and the `completionHandler` is called with an error.
+     *      Pass `0` to prevent a write from timing out.
+     * - Parameter completionHandler: The completion handler to call when all bytes are written, or an error occurs.
+     *      This handler is executed on the delegate queue.
+     *      This completion handler takes the following parameter:
+     *      - error: An error object that indicates why the write failed, or nil if the write was successful.
+    */
+    open func write(_ data: Data, timeout: TimeInterval, completionHandler: @escaping (_ error: Error?) -> Void) {
+        if #available(iOS 9.0, OSX 10.11, *) {
+            if self.useURLSession {
+                _underlyingTask!.write(data, timeout: timeout, completionHandler: completionHandler)
+                return
+            }
+        }
+        
+        guard outputStream != nil else {
+            return
+        }
+        
+        
+        operation_queue.addOperation {
+            self.dataToBeSent.append(data)
+            let result = self.write(timeout: timeout, close: false)
+            if result < 0 {
+                let error = self.outputStream?.streamError ?? NSError(domain: URLError.errorDomain, code: URLError.cannotWriteToFile.rawValue, userInfo: nil)
+                completionHandler(error)
+            } else {
+                completionHandler(nil)
+            }
+        }
+    }
+    
+    /**
+     * Completes any already enqueued reads and writes, and then invokes the 
+     * `urlSession(_:streamTask:didBecome:outputStream:)` delegate message.
+    */
+    open func captureStreams() {
+        if #available(iOS 9.0, OSX 10.11, *) {
+            if self.useURLSession {
+                _underlyingTask!.captureStreams()
+                return
+            }
+        }
+        
+        guard let outputStream = outputStream, let inputStream = inputStream else {
+            return
+        }
+        self.operation_queue.addOperation {
+            _=self.write(close: false)
+            while inputStream.streamStatus != .atEnd || outputStream.streamStatus == .writing {
+                Thread.sleep(forTimeInterval: 0.1)
+            }
+            self.streamDelegate?.urlSession?(self._underlyingSession, streamTask: self, didBecome: inputStream, outputStream: outputStream)
+        }
+    }
+    
+    /**
+     * Completes any enqueued reads and writes, and then closes the write side of the underlying socket.
+     *
+     * You may continue to read data using the `readData(ofMinLength:maxLength:timeout:completionHandler:)`
+     * method after calling this method. Any calls to `write(_:timeout:completionHandler:)` after calling 
+     * this method will result in an error.
+     *
+     * Because the server may continue to write bytes to the client, it is recommended that 
+     * you continue reading until the stream reaches end-of-file (EOF).
+    */
+    open func closeWrite() {
+        if #available(iOS 9.0, OSX 10.11, *) {
+            if self.useURLSession {
+                _underlyingTask!.closeWrite()
+                return
+            }
+        }
+        
+        operation_queue.addOperation {
+            _ = self.write(close: true)
+        }
+    }
+    
+    fileprivate func write(timeout: TimeInterval = 0, close: Bool) -> Int {
+        guard let outputStream = outputStream else {
+            return -1
+        }
+        
+        var byteSent: Int = 0
+        let expireDate = Date(timeIntervalSinceNow: timeout)
+        while self.dataToBeSent.count > 0 && (timeout == 0 || expireDate > Date()) {
+            let bytesWritten = self.dataToBeSent.withUnsafeBytes {
+                outputStream.write($0, maxLength: self.dataToBeSent.count)
+            }
+            
+            if bytesWritten > 0 {
+                let range = 0..<bytesWritten
+                self.dataToBeSent.replaceSubrange(range, with: Data())
+                byteSent += bytesWritten
+            } else if bytesWritten < 0 {
+                self._error = outputStream.streamError
+                return bytesWritten
+            }
+            if self.dataToBeSent.count == 0 {
                break
            }
-            RunLoop.current.run(until: Date(timeIntervalSinceNow: 0.1));
-            Thread.sleep(forTimeInterval: 0.1)
        }
+        self._countOfBytesSent += Int64(byteSent)
        if close {
            outputStream.close()
            self.streamDelegate?.urlSession?(self._underlyingSession, writeClosedFor: self)
        }
+        return byteSent
    }
    
-    /* Enqueue a request to close the read side of the underlying socket.
-     * All outstanding IO will complete before the read side is closed.
-     * You may continue writing to the server.
-     */
+    /**
+     * Completes any enqueued reads and writes, and then closes the read side of the underlying socket.
+     *
+     * You may continue to write data using the `write(_:timeout:completionHandler:)` method after 
+     * calling this method. Any calls to `readData(ofMinLength:maxLength:timeout:completionHandler:)`
+     * after calling this method will result in an error.
+    */
    open func closeRead() {
        if #available(iOS 9.0, OSX 10.11, *) {
-            _underlyingTask!.closeRead()
-        } else {
-            guard let inputStream = inputStream else {
+            if self.useURLSession {
+                _underlyingTask!.closeRead()
                return
            }
-            dispatch_queue.async {
-                while inputStream.streamStatus != .atEnd {
-                    RunLoop.current.run(until: Date(timeIntervalSinceNow: 0.1));
-                    Thread.sleep(forTimeInterval: 0.1)
-                }
-                inputStream.close()
-                self.streamDelegate?.urlSession?(self._underlyingSession, readClosedFor: self)
+        }
+        
+        guard let inputStream = inputStream else {
+            return
+        }
+        operation_queue.addOperation {
+            while inputStream.streamStatus != .atEnd {
+                Thread.sleep(forTimeInterval: 0.1)
            }
+            inputStream.close()
+            self.streamDelegate?.urlSession?(self._underlyingSession, readClosedFor: self)
        }
    }
    
-    /*
-     * Begin encrypted handshake.  The hanshake begins after all pending
-     * IO has completed.  TLS authentication callbacks are sent to the
-     * session's -URLSession:task:didReceiveChallenge:completionHandler:
-     */
+    /**
+     * Completes any enqueued reads and writes, and establishes a secure connection.
+     *
+     * Authentication callbacks are sent to the session's delegate using the
+     * `urlSession(_:task:didReceive:completionHandler:)` method.
+    */
    open func startSecureConnection() {
        if #available(iOS 9.0, OSX 10.11, *) {
-            _underlyingTask!.startSecureConnection()
-        } else {
-            inputStream!.setProperty(StreamSocketSecurityLevel.negotiatedSSL.rawValue, forKey: .socketSecurityLevelKey)
-            outputStream!.setProperty(StreamSocketSecurityLevel.negotiatedSSL.rawValue, forKey: .socketSecurityLevelKey)
+            if self.useURLSession {
+                _underlyingTask!.startSecureConnection()
+                return
+            }
+        }
+        
+        operation_queue.addOperation {
+            self.inputStream!.setProperty(StreamSocketSecurityLevel.negotiatedSSL.rawValue, forKey: .socketSecurityLevelKey)
+            self.outputStream!.setProperty(StreamSocketSecurityLevel.negotiatedSSL.rawValue, forKey: .socketSecurityLevelKey)
        }
    }
    
-    /*
-     * Cleanly close a secure connection after all pending secure IO has
-     * completed.
-     */
+    /**
+     * Completes any enqueued reads and writes, and closes the secure connection.
+    */
    open func stopSecureConnection() {
        if #available(iOS 9.0, OSX 10.11, *) {
-            _underlyingTask!.stopSecureConnection()
-        } else {
-            inputStream!.setProperty(StreamSocketSecurityLevel.none.rawValue, forKey: .socketSecurityLevelKey)
-            outputStream!.setProperty(StreamSocketSecurityLevel.none.rawValue, forKey: .socketSecurityLevelKey)
+            if self.useURLSession {
+                _underlyingTask!.stopSecureConnection()
+                return
+            }
+        }
+        operation_queue.addOperation {
+            self.inputStream!.setProperty(StreamSocketSecurityLevel.none.rawValue, forKey: .socketSecurityLevelKey)
+            self.outputStream!.setProperty(StreamSocketSecurityLevel.none.rawValue, forKey: .socketSecurityLevelKey)
        }
    }
    
    open func stream(_ aStream: Stream, handle eventCode: Stream.Event) {
-        switch (eventCode) {
-        case Stream.Event.errorOccurred:
-            self._error = aStream.streamError as NSError?
+        if eventCode.contains(.errorOccurred) {
+            self._error = aStream.streamError
            streamDelegate?.urlSession?(_underlyingSession, task: self, didCompleteWithError: error)
-        case Stream.Event.endEncountered:
-            break
-        case Stream.Event():
-            break
-        case Stream.Event.openCompleted:
-            break
-        case Stream.Event.hasBytesAvailable:
-            var buffer = [UInt8](repeating: 0, count: 2048)
-            if (aStream == inputStream) {
-                while (inputStream!.hasBytesAvailable) {
-                    let len = inputStream!.read(&buffer, maxLength: buffer.count)
-                    if len > 0 {
-                        dataReceived.append(&buffer, length: len)
-                        self._countOfBytesRecieved += len
-                    }
+        }
+        
+        if aStream == inputStream && eventCode.contains(.hasBytesAvailable) {
+            while (inputStream!.hasBytesAvailable) {
+                var buffer = [UInt8](repeating: 0, count: 2048)
+                let len = inputStream!.read(&buffer, maxLength: buffer.count)
+                if len > 0 {
+                    dataReceived.append(&buffer, count: len)
+                    self._countOfBytesRecieved += Int64(len)
                }
            }
-        case Stream.Event.hasSpaceAvailable:
-            break
-        default:
-            break
        }
    }
 }

-extension URLSession {
-    /* Creates a bidirectional stream task to a given host and port.
-     */
-    public func fpstreamTaskWithHostName(_ hostname: String, port: Int) -> FPSStreamTask {
-        return FPSStreamTask(session: self, host: hostname, port: port)
+public extension URLSession {
+    /// Creates a bidirectional stream task to a given host and port.
+    func fpstreamTask(withHostName hostname: String, port: Int) -> FileProviderStreamTask {
+        return FileProviderStreamTask(session: self, host: hostname, port: port)
    }
    
-    /* Creates a bidirectional stream task with an NSNetService to identify the endpoint.
+    /**
+     * Creates a bidirectional stream task with an NSNetService to identify the endpoint.
     * The NSNetService will be resolved before any IO completes.
-     */
-    public func fpstreamTaskWithNetService(_ service: NetService) -> FPSStreamTask {
-        return fpstreamTaskWithNetService(service)
+    */
+    func fpstreamTask(withNetService service: NetService) -> FileProviderStreamTask {
+        return FileProviderStreamTask(session: self, netService: service)
    }
 }

@objc
-public protocol FPSStreamDelegate : URLSessionTaskDelegate {
+internal protocol FPSStreamDelegate : URLSessionTaskDelegate {
    
    
-    /* Indiciates that the read side of a connection has been closed.  Any
+    /**
+     * Indiciates that the read side of a connection has been closed.  Any
     * outstanding reads complete, but future reads will immediately fail.
     * This may be sent even when no reads are in progress. However, when
     * this delegate message is received, there may still be bytes
     * available.  You only know that no more bytes are available when you
     * are able to read until EOF. */
-    @objc optional func urlSession(_ session: URLSession, readClosedFor streamTask: FPSStreamTask)
+    @objc optional func urlSession(_ session: URLSession, readClosedFor streamTask: FileProviderStreamTask)
    
    
-    /* Indiciates that the write side of a connection has been closed.
+    /**
+     * Indiciates that the write side of a connection has been closed.
     * Any outstanding writes complete, but future writes will immediately
     * fail.
     */
-    @objc optional func urlSession(_ session: URLSession, writeClosedFor streamTask: FPSStreamTask)
+    @objc optional func urlSession(_ session: URLSession, writeClosedFor streamTask: FileProviderStreamTask)
    
    
-    /* A notification that the system has determined that a better route
+    /**
+     * A notification that the system has determined that a better route
     * to the host has been detected (eg, a wi-fi interface becoming
     * available.)  This is a hint to the delegate that it may be
     * desirable to create a new task for subsequent work.  Note that
     * there is no guarantee that the future task will be able to connect
     * to the host, so callers should should be prepared for failure of
     * reads and writes over any new interface. */
-    @objc optional func urlSession(_ session: URLSession, betterRouteDiscoveredFor streamTask: FPSStreamTask)
+    @objc optional func urlSession(_ session: URLSession, betterRouteDiscoveredFor streamTask: FileProviderStreamTask)
    
    
-    /* The given task has been completed, and unopened NSInputStream and
+    /**
+     * The given task has been completed, and unopened NSInputStream and
     * NSOutputStream objects are created from the underlying network
     * connection.  This will only be invoked after all enqueued IO has
     * completed (including any necessary handshakes.)  The streamTask
     * will not receive any further delegate messages.
     */
-    @objc optional func urlSession(_ session: URLSession, streamTask: FPSStreamTask, didBecome inputStream: InputStream, outputStream: OutputStream)
+    @objc optional func urlSession(_ session: URLSession, streamTask: FileProviderStreamTask, didBecome inputStream: InputStream, outputStream: OutputStream)
 }

-private let ports: [String: Int] = ["http": 80, "https": 443, "smb": 445,"ftp": 21,"ftps": 22, "sftp": 2121,
+private let ports: [String: Int] = ["http": 80, "https": 443, "smb": 445,"ftp": 21,
                                    "telnet": 23, "pop": 110, "smtp": 25, "imap": 143]
-private let securePorts: [String: Int] =  ["https": 443, "smb": 445, "ftps": 22, "sftp": 2121,
-                                           "telnet": 992, "pop": 995, "smtp": 465, "imap": 993]
+private let securePorts: [String: Int] =  ["ssh": 22, "https": 443, "smb": 445, "smtp": 465,
+                                            "ftps": 990,"telnet": 992, "imap": 993, "pop": 995]
@@ -0,0 +1,784 @@
+//
+//  FTPFileProvider.swift
+//  FileProvider
+//
+//  Created by Amir Abbas Mousavian.
+//  Copyright © 2017 Mousavian. Distributed under MIT license.
+//
+
+import Foundation
+
+/**
+ Allows accessing to FTP files and directories. This provider doesn't cache or save files internally.
+ It's a complete reimplementation and doesn't use CFNetwork deprecated API.
+ */
+open class FTPFileProvider: FileProviderBasicRemote {
+    open class var type: String { return "FTP" }
+    open let baseURL: URL?
+    open var currentPath: String
+    
+    open var dispatch_queue: DispatchQueue
+    open var operation_queue: OperationQueue {
+        willSet {
+            assert(_session == nil, "It's not effective to change dispatch_queue property after session is initialized.")
+        }
+    }
+    
+    open weak var delegate: FileProviderDelegate?
+    open var credential: URLCredential? {
+        didSet {
+            sessionDelegate?.credential = self.credential
+        }
+    }
+    open private(set) var cache: URLCache?
+    public var useCache: Bool
+    public var validatingCache: Bool
+    
+    /// Determine either FTP session is in passive or active mode.
+    /// - Note: Due to `URLSessionStreamTask` restrictions for determining listening port,
+    /// only passive sessions are available in current implementation.
+    public let passiveMode = true
+    
+    /// Force to use URLSessionDownloadTask/URLSessionDataTask when possible
+    public var useAppleImplementation = true
+    
+    fileprivate var _session: URLSession?
+    internal var sessionDelegate: SessionDelegate?
+    public var session: URLSession {
+        get {
+            if _session == nil {
+                self.sessionDelegate = SessionDelegate(fileProvider: self)
+                let config = URLSessionConfiguration.default
+                config.urlCache = cache
+                config.requestCachePolicy = .returnCacheDataElseLoad
+                _session = URLSession(configuration: config, delegate: sessionDelegate as URLSessionDelegate?, delegateQueue: self.operation_queue)
+                _session?.sessionDescription = UUID().uuidString
+                initEmptySessionHandler(_session!.sessionDescription!)
+            }
+            return _session!
+        }
+        
+        set {
+            assert(newValue.delegate is SessionDelegate, "session instances should have a SessionDelegate instance as delegate.")
+            _session = newValue
+            if session.sessionDescription?.isEmpty ?? true {
+                _session?.sessionDescription = UUID().uuidString
+            }
+            self.sessionDelegate = newValue.delegate as? SessionDelegate
+            initEmptySessionHandler(_session!.sessionDescription!)
+        }
+    }
+    
+    /**
+     Initializer for FTP provider with given username and password.
+     
+     - Parameter baseURL: a url with `ftp://hostaddress/` format.
+     - Parameter credential: a `URLCredential` object contains user and password.
+     - Parameter cache: A URLCache to cache downloaded files and contents. (unimplemented for FTP and should be nil)
+     */
+    public init? (baseURL: URL, credential: URLCredential? = nil, cache: URLCache? = nil) {
+        guard (baseURL.scheme ?? "ftp").lowercased().hasPrefix("ftp") else { return nil }
+        guard baseURL.host != nil else { return nil }
+        var urlComponents = URLComponents(url: baseURL, resolvingAgainstBaseURL: true)!
+        urlComponents.port = urlComponents.port ?? 21
+        urlComponents.scheme = urlComponents.scheme ?? "ftp"
+        
+        self.baseURL =  (urlComponents.url!.path.hasSuffix("/") ? urlComponents.url! : urlComponents.url!.appendingPathComponent("")).absoluteURL
+        self.currentPath = ""
+        self.useCache = false
+        self.validatingCache = true
+        self.cache = cache
+        self.credential = credential
+        
+        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: [])
+        operation_queue = OperationQueue()
+        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
+    }
+    
+    public required convenience init?(coder aDecoder: NSCoder) {
+        guard let baseURL = aDecoder.decodeObject(forKey: "baseURL") as? URL else { return nil }
+        self.init(baseURL: baseURL, credential: aDecoder.decodeObject(forKey: "credential") as? URLCredential)
+        self.currentPath     = aDecoder.decodeObject(forKey: "currentPath") as? String ?? ""
+        self.useCache        = aDecoder.decodeBool(forKey: "useCache")
+        self.validatingCache = aDecoder.decodeBool(forKey: "validatingCache")
+        self.useAppleImplementation = aDecoder.decodeBool(forKey: "useAppleImplementation")
+    }
+    
+    public func encode(with aCoder: NSCoder) {
+        aCoder.encode(self.baseURL, forKey: "baseURL")
+        aCoder.encode(self.credential, forKey: "credential")
+        aCoder.encode(self.currentPath, forKey: "currentPath")
+        aCoder.encode(self.useCache, forKey: "useCache")
+        aCoder.encode(self.validatingCache, forKey: "validatingCache")
+        aCoder.encode(self.useAppleImplementation, forKey: "useAppleImplementation")
+    }
+    
+    public static var supportsSecureCoding: Bool {
+        return true
+    }
+    
+    open func copy(with zone: NSZone? = nil) -> Any {
+        let copy = FTPFileProvider(baseURL: self.baseURL!, credential: self.credential, cache: self.cache)!
+        copy.currentPath = self.currentPath
+        copy.delegate = self.delegate
+        copy.fileOperationDelegate = self.fileOperationDelegate
+        copy.useCache = self.useCache
+        copy.validatingCache = self.validatingCache
+        copy.useAppleImplementation = self.useAppleImplementation
+        return copy
+    }
+    
+    deinit {
+        if let sessionuuid = _session?.sessionDescription {
+            removeSessionHandler(for: sessionuuid)
+        }
+        
+        if fileProviderCancelTasksOnInvalidating {
+            _session?.invalidateAndCancel()
+        } else {
+            _session?.finishTasksAndInvalidate()
+        }
+    }
+    
+    public func contentsOfDirectory(path: String, completionHandler: @escaping (([FileObject], Error?) -> Void)) {
+        self.contentsOfDirectory(path: path, rfc3659enabled: true, completionHandler: completionHandler)
+    }
+    
+    /**
+     Returns an Array of `FileObject`s identifying the the directory entries via asynchronous completion handler.
+     
+     If the directory contains no entries or an error is occured, this method will return the empty array.
+     
+     - Parameter path: path to target directory. If empty, `currentPath` value will be used.
+     - Parameter rfc3659enabled: uses MLST command instead of old LIST to get files attributes, default is `true`.
+     - Parameter completionHandler: a closure with result of directory entries or error.
+         `contents`: An array of `FileObject` identifying the the directory entries.
+         `error`: Error returned by system.
+     */
+    
+    open func contentsOfDirectory(path apath: String, rfc3659enabled: Bool , completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
+        let path = ftpPath(apath)
+        
+        let task = session.fpstreamTask(withHostName: baseURL!.host!, port: baseURL!.port!)
+        self.ftpLogin(task) { (error) in
+            if let error = error {
+                self.dispatch_queue.async {
+                    completionHandler([], error)
+                }
+                return
+            }
+            
+            self.ftpList(task, of: self.ftpPath(path), useMLST: rfc3659enabled, completionHandler: { (contents, error) in
+                defer {
+                    self.ftpQuit(task)
+                }
+                if let error = error {
+                    self.dispatch_queue.async {
+                        completionHandler([], error)
+                    }
+                    return
+                }
+                
+                
+                let files: [FileObject] = contents.flatMap {
+                    rfc3659enabled ? self.parseMLST($0, in: path) : self.parseUnixList($0, in: path)
+                }
+                
+                self.dispatch_queue.async {
+                    completionHandler(files, nil)
+                }
+            })
+        }
+    }
+    
+    public func attributesOfItem(path: String, completionHandler: @escaping ((FileObject?, Error?) -> Void)) {
+        self.attributesOfItem(path: path, rfc3659enabled: true, completionHandler: completionHandler)
+    }
+    
+    /**
+     Returns a `FileObject` containing the attributes of the item (file, directory, symlink, etc.) at the path in question via asynchronous completion handler.
+     
+     If the directory contains no entries or an error is occured, this method will return the empty `FileObject`.
+     
+     - Parameter path: path to target directory. If empty, `currentPath` value will be used.
+     - Parameter rfc3659enabled: uses MLST command instead of old LIST to get files attributes, default is true.
+     - Parameter completionHandler: a closure with result of directory entries or error.
+         `attributes`: A `FileObject` containing the attributes of the item.
+         `error`: Error returned by system.
+     */
+    open func attributesOfItem(path apath: String, rfc3659enabled: Bool, completionHandler: @escaping ((_ attributes: FileObject?, _ error: Error?) -> Void)) {
+        let path = ftpPath(apath)
+        
+        let task = session.fpstreamTask(withHostName: baseURL!.host!, port: baseURL!.port!)
+        self.ftpLogin(task) { (error) in
+            if let error = error {
+                self.dispatch_queue.async {
+                    completionHandler(nil, error)
+                }
+                return
+            }
+            
+            let command = rfc3659enabled ? "MLST \(path)" : "LIST \(path)"
+            self.execute(command: command, on: task, completionHandler: { (response, error) in
+                defer {
+                    self.ftpQuit(task)
+                }
+                if let error = error {
+                    self.dispatch_queue.async {
+                        completionHandler(nil, error)
+                    }
+                    return
+                }
+                
+                guard let response = response, response.hasPrefix("250") || (response.hasPrefix("50") && rfc3659enabled) else {
+                    self.dispatch_queue.async {
+                        completionHandler(nil, self.throwError(path, code: URLError.badServerResponse))
+                    }
+                    return
+                }
+                
+                if response.hasPrefix("500") {
+                    self.attributesOfItem(path: path, rfc3659enabled: false, completionHandler: completionHandler)
+                }
+                
+                let lines = response.components(separatedBy: "\n").flatMap { $0.isEmpty ? nil : $0.trimmingCharacters(in: .whitespacesAndNewlines) }
+                guard lines.count > 2 else {
+                    self.dispatch_queue.async {
+                        completionHandler(nil, self.throwError(path, code: URLError.badServerResponse))
+                    }
+                    return
+                }
+                let file = rfc3659enabled ? self.parseMLST(lines[1], in: path) : self.parseUnixList(lines[1], in: path)
+                self.dispatch_queue.async {
+                    completionHandler(file, nil)
+                }
+            })
+        }
+    }
+    
+    open func storageProperties(completionHandler: @escaping ((_ total: Int64, _ used: Int64) -> Void)) {
+        dispatch_queue.async {
+            completionHandler(-1, 0)
+        }
+    }
+    
+    open func searchFiles(path: String, recursive: Bool, query: NSPredicate, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
+        self.recursiveList(path: path, useMLST: true, foundItemsHandler: { items in
+            if let foundItemHandler = foundItemHandler {
+                for item in items where query.evaluate(with: item.mapPredicate()) {
+                    foundItemHandler(item)
+                }
+            }
+        }, completionHandler: {files, error in
+            if let error = error {
+                completionHandler([], error)
+                return
+            }
+            
+            let foundFiles = files.filter { query.evaluate(with: $0.mapPredicate()) }
+            completionHandler(foundFiles, nil)
+        })
+    }
+    
+    public func url(of path: String?) -> URL {
+        let path = (path ?? self.currentPath).trimmingCharacters(in: CharacterSet(charactersIn: "/ ")).addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) ?? (path ?? self.currentPath)
+        
+        var baseUrlComponent = URLComponents(url: self.baseURL!, resolvingAgainstBaseURL: true)
+        baseUrlComponent?.user = credential?.user
+        baseUrlComponent?.password = credential?.password
+        return URL(string: path, relativeTo: baseUrlComponent?.url ?? baseURL) ?? baseUrlComponent?.url ?? baseURL!
+    }
+    
+    public func relativePathOf(url: URL) -> String {
+        // check if url derieved from current base url
+        let relativePath = url.relativePath
+        if !relativePath.isEmpty, url.baseURL == self.baseURL {
+            return (relativePath.removingPercentEncoding ?? relativePath).replacingOccurrences(of: "/", with: "", options: .anchored)
+        }
+        
+        if !relativePath.isEmpty, self.baseURL == self.url(of: "/") {
+            return (relativePath.removingPercentEncoding ?? relativePath).replacingOccurrences(of: "/", with: "", options: .anchored)
+        }
+        
+        return relativePath.replacingOccurrences(of: "/", with: "", options: .anchored)
+    }
+    
+    open func isReachable(completionHandler: @escaping (Bool) -> Void) {
+        self.attributesOfItem(path: "/") { (file, error) in
+            completionHandler(file != nil)
+        }
+    }
+    
+    open weak var fileOperationDelegate: FileOperationDelegate?
+}
+
+extension FTPFileProvider: FileProviderOperations {
+    open func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let path = (atPath as NSString).appendingPathComponent(folderName) + "/"
+        return doOperation(.create(path: path), completionHandler: completionHandler)
+    }
+    
+    open func moveItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        return doOperation(.move(source: path, destination: toPath), completionHandler: completionHandler)
+    }
+    
+    open func copyItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        return doOperation(.copy(source: path, destination: toPath), completionHandler: completionHandler)
+    }
+    
+    open func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        return doOperation(.remove(path: path), completionHandler: completionHandler)
+    }
+    
+    fileprivate func doOperation(_ opType: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
+            return nil
+        }
+        guard let sourcePath = opType.source else { return nil }
+        let destPath = opType.destination
+        
+        let command: String
+        switch opType {
+        case .create:
+            command = "MKD \(ftpPath(sourcePath))"
+        case .copy:
+            command = "SITE CPFR \(ftpPath(sourcePath))\r\nSITE CPTO \(ftpPath(destPath!))"
+        case .move:
+            command = "RNFR \(ftpPath(sourcePath))\r\nRNTO \(ftpPath(destPath!))"
+        case .remove:
+            command = "DELE \(ftpPath(sourcePath))"
+        case .link:
+            command = "SITE SYMLINK \(ftpPath(sourcePath)) \(ftpPath(destPath!))"
+        default: // modify, fetch
+            return nil
+        }
+        let operationHandle = RemoteOperationHandle(operationType: opType, tasks: [])
+        
+        let task = session.fpstreamTask(withHostName: baseURL!.host!, port: baseURL!.port!)
+        self.ftpLogin(task) { (error) in
+            if let error = error {
+                self.dispatch_queue.async {
+                    completionHandler?(error)
+                    self.delegateNotify(opType, error: error)
+                }
+                return
+            }
+            
+            self.execute(command: command, on: task, completionHandler: { (response, error) in
+                if let error = error {
+                    self.dispatch_queue.async {
+                        completionHandler?(error)
+                        self.delegateNotify(opType, error: error)
+                    }
+                    return
+                }
+                
+                guard let response = response else {
+                    self.dispatch_queue.async {
+                        completionHandler?(error)
+                        self.delegateNotify(opType, error: self.throwError(sourcePath, code: URLError.badServerResponse))
+                    }
+                    return
+                }
+                
+                let codes: [Int] = response.components(separatedBy: .newlines).flatMap({ $0.isEmpty ? nil : $0})
+                .flatMap {
+                    let code = $0.components(separatedBy: .whitespaces).flatMap({ $0.isEmpty ? nil : $0}).first
+                    return code != nil ? Int(code!) : nil
+                }
+                
+                if codes.filter({ (450..<560).contains($0) }).count > 0 {
+                    let errorCode: URLError.Code
+                    switch opType {
+                    case .create:
+                        errorCode = URLError.cannotCreateFile
+                    case .modify:
+                        errorCode = URLError.cannotWriteToFile
+                    case .copy:
+                        let opHandle = self.fallbackCopy(opType, completionHandler: completionHandler) as? RemoteOperationHandle
+                        operationHandle.tasks = opHandle?.tasks ?? []
+                        return
+                    case .move:
+                        errorCode = URLError.cannotMoveFile
+                    case .remove:
+                        self.fallbackRemove(opType, on: task, completionHandler: completionHandler)
+                        return
+                    case .link:
+                        errorCode = URLError.cannotWriteToFile
+                    default:
+                        errorCode = URLError.cannotOpenFile
+                    }
+                    let error = self.throwError(sourcePath, code: errorCode)
+                    self.dispatch_queue.async {
+                        completionHandler?(error)
+                        self.delegateNotify(opType, error: error)
+                    }
+                    return
+                }
+                
+                self.dispatch_queue.async {
+                    completionHandler?(nil)
+                    self.delegateNotify(opType, error: nil)
+                }
+            })
+        }
+        
+        operationHandle.add(task: task)
+        return operationHandle
+    }
+    
+    private func fallbackCopy(_ opType: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        guard let sourcePath = opType.source else { return nil }
+        guard let destPath = opType.destination else { return nil }
+        
+        let localURL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(UUID().uuidString).appendingPathExtension("tmp")
+        let operationHandle = RemoteOperationHandle(operationType: opType, tasks: [])
+        let firstOp = self.copyItem(path: sourcePath, toLocalURL: localURL, completionHandler: { (error) in
+            if let error = error {
+                self.dispatch_queue.async {
+                    completionHandler?(error)
+                    self.delegateNotify(opType, error: error)
+                }
+                return
+            }
+            
+            let secondOp = self.copyItem(localFile: localURL, to: destPath, completionHandler: completionHandler) as? RemoteOperationHandle
+            operationHandle.tasks = secondOp?.tasks ?? []
+        }) as? RemoteOperationHandle
+        operationHandle.tasks = firstOp?.tasks ?? []
+        return operationHandle
+    }
+    
+    private func fallbackRemove(_ opType: FileOperationType, on task: FileProviderStreamTask, completionHandler: SimpleCompletionHandler) {
+        guard let sourcePath = opType.source else { return }
+        
+        self.execute(command: "SITE RMDIR \(ftpPath(sourcePath))", on: task) { (response, error) in
+            if let error = error {
+                self.dispatch_queue.async {
+                    completionHandler?(error)
+                    self.delegateNotify(opType, error: error)
+                }
+                return
+            }
+            
+            guard let response = response else {
+                let error = self.throwError(sourcePath, code: URLError.badServerResponse)
+                self.dispatch_queue.async {
+                    completionHandler?(error)
+                    self.delegateNotify(opType, error: error)
+                }
+                return
+            }
+            
+            if response.hasPrefix("50") {
+                self.fallbackRecursiveRemove(opType, on: task, completionHandler: completionHandler)
+                return
+            }
+            
+            let error = self.throwError(sourcePath, code: URLError.cannotRemoveFile)
+            self.dispatch_queue.async {
+                completionHandler?(error)
+                self.delegateNotify(opType, error: error)
+            }
+        }
+    }
+    
+    private func fallbackRecursiveRemove(_ opType: FileOperationType, on task: FileProviderStreamTask, completionHandler: SimpleCompletionHandler) {
+        guard let sourcePath = opType.source else { return }
+        
+        self.recursiveList(path: sourcePath, useMLST: true, completionHandler: { (contents, error) in
+            if let error = error {
+                self.dispatch_queue.async {
+                    completionHandler?(error)
+                    self.delegateNotify(opType, error: error)
+                }
+                return
+            }
+            
+            let sortedContents = contents.sorted(by: {
+                $0.path.localizedStandardCompare($1.path) == .orderedDescending
+            })
+            var command = ""
+            for file in sortedContents {
+                command += (file.isDirectory ? "RMD \(self.ftpPath(file.path))" : "DELE \(self.ftpPath(file.path))") + "\r\n"
+            }
+            command += "RMD \(self.ftpPath(sourcePath))"
+            
+            self.execute(command: command, on: task, completionHandler: { (response, error) in
+                self.dispatch_queue.async {
+                    completionHandler?(error)
+                    self.delegateNotify(opType, error: error)
+                }
+                // TODO: Digest response
+            })
+        })
+    }
+    
+    open func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        // check file is not a folder
+        guard (try? localFile.resourceValues(forKeys: [.fileResourceTypeKey]))?.fileResourceType ?? .unknown == .regular else {
+            dispatch_queue.async {
+                completionHandler?(self.throwError(localFile.path, code: URLError.fileIsDirectory))
+            }
+            return nil
+        }
+        
+        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
+        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
+            return nil
+        }
+        let operation = RemoteOperationHandle(operationType: opType, tasks: [])
+        
+        let task = session.fpstreamTask(withHostName: baseURL!.host!, port: baseURL!.port!)
+        self.ftpLogin(task) { (error) in
+            if let error = error {
+                self.dispatch_queue.async {
+                    completionHandler?(error)
+                    self.delegateNotify(opType, error: error)
+                }
+                return
+            }
+            
+            self.ftpStore(task, filePath: self.ftpPath(toPath), fromData: nil, fromFile: localFile, onTask: {
+                operation.add(task: $0)
+                $0.taskDescription = opType.json
+            }, onProgress: { bytesSent, totalSent, expectedBytes in
+                DispatchQueue.main.async {
+                    self.delegate?.fileproviderProgress(self, operation: opType, progress: Float(Double(totalSent) / Double(expectedBytes)))
+                }
+            }, completionHandler: { (error) in
+                self.ftpQuit(task)
+                self.dispatch_queue.async {
+                    completionHandler?(error)
+                    self.delegateNotify(opType, error: error)
+                }
+            })
+        }
+        
+        return operation
+    }
+    
+    open func copyItem(path: String, toLocalURL destURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let opType = FileOperationType.copy(source: path, destination: destURL.absoluteString)
+        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
+            return nil
+        }
+        let operation = RemoteOperationHandle(operationType: opType, tasks: [])
+        
+        if self.useAppleImplementation {
+            self.attributesOfItem(path: path, completionHandler: { (file, error) in
+                if let error = error {
+                    self.dispatch_queue.async {
+                        completionHandler?(error)
+                        self.delegateNotify(opType, error: error)
+                    }
+                    return
+                }
+                
+                if file?.isDirectory ?? false {
+                    self.dispatch_queue.async {
+                        let error = self.throwError(path, code: URLError.fileIsDirectory)
+                        completionHandler?(error)
+                        self.delegateNotify(opType, error: error)
+                    }
+                    return
+                }
+                
+                let task = self.session.downloadTask(with: self.url(of: path))
+                completionHandlersForTasks[self.session.sessionDescription!]?[task.taskIdentifier] = completionHandler
+                downloadCompletionHandlersForTasks[self.session.sessionDescription!]?[task.taskIdentifier] = { tempURL in
+                    do {
+                        try FileManager.default.moveItem(at: tempURL, to: destURL)
+                        completionHandler?(nil)
+                    } catch let e {
+                        completionHandler?(e)
+                    }
+                }
+                operation.add(task: task)
+                task.taskDescription = opType.json
+                task.resume()
+            })
+        } else {
+            let task = session.fpstreamTask(withHostName: baseURL!.host!, port: baseURL!.port!)
+            self.ftpLogin(task) { (error) in
+                if let error = error {
+                    self.dispatch_queue.async {
+                        completionHandler?(error)
+                    }
+                    return
+                }
+                
+                self.ftpRetrieveFile(task, filePath: self.ftpPath(path), onTask: {
+                    operation.add(task: $0)
+                    $0.taskDescription = opType.json
+                }, onProgress: { recevied, totalReceived, totalSize in
+                    let progress = Double(totalReceived) / Double(totalSize)
+                    self.delegate?.fileproviderProgress(self, operation: opType, progress: Float(progress))
+                }) { (tmpurl, error) in
+                    if let error = error {
+                        self.dispatch_queue.async {
+                            completionHandler?(error)
+                            self.delegateNotify(opType, error: error)
+                        }
+                        return
+                    }
+                    
+                    if let tmpurl = tmpurl {
+                        try? FileManager.default.moveItem(at: tmpurl, to: destURL)
+                        self.dispatch_queue.async {
+                            completionHandler?(nil)
+                            self.delegateNotify(opType, error: nil)
+                        }
+                    }
+                }
+            }
+        }
+        return operation
+    }
+}
+
+extension FTPFileProvider: FileProviderReadWrite {
+    public func contents(path: String, completionHandler: @escaping ((Data?, Error?) -> Void)) -> OperationHandle? {
+        let opType = FileOperationType.fetch(path: path)
+        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
+            return nil
+        }
+        
+        if self.useAppleImplementation {
+            let task = session.downloadTask(with: url(of: path))
+            completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { error in
+                completionHandler(nil, error)
+            }
+            downloadCompletionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { tempURL in
+                do {
+                    let data = try Data(contentsOf: tempURL)
+                    completionHandler(data, nil)
+                } catch let e {
+                    completionHandler(nil, e)
+                }
+            }
+            task.taskDescription = opType.json
+            task.resume()
+            return RemoteOperationHandle(operationType: opType, tasks: [task])
+        } else {
+            return self.contents(path: path, offset: 0, length: -1, completionHandler: completionHandler)
+        }
+    }
+    
+    open func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
+        let opType = FileOperationType.fetch(path: path)
+        if length == 0 || offset < 0 {
+            dispatch_queue.async {
+                completionHandler(Data(), nil)
+                self.delegateNotify(opType, error: nil)
+            }
+            return nil
+        }
+        let operation = RemoteOperationHandle(operationType: opType, tasks: [])
+        
+        let task = session.fpstreamTask(withHostName: baseURL!.host!, port: baseURL!.port!)
+        self.ftpLogin(task) { (error) in
+            if let error = error {
+                self.dispatch_queue.async {
+                    completionHandler(nil, error)
+                }
+                return
+            }
+            
+            self.ftpRetrieveData(task, filePath: self.ftpPath(path), from: offset, length: length, onTask: {
+                operation.add(task: $0)
+                $0.taskDescription = opType.json
+            }, onProgress: { recevied, totalReceived, totalSize in
+                let progress = Double(totalReceived) / Double(totalSize)
+                self.delegate?.fileproviderProgress(self, operation: opType, progress: Float(progress))
+            }) { (data, error) in
+                if let error = error {
+                    self.dispatch_queue.async {
+                        completionHandler(nil, error)
+                        self.delegateNotify(opType, error: error)
+                    }
+                    return
+                }
+                
+                if let data = data {
+                    self.dispatch_queue.async {
+                        completionHandler(data, nil)
+                        self.delegateNotify(opType, error: nil)
+                    }
+                }
+            }
+        }
+        
+        return operation
+    }
+    
+    public func writeContents(path: String, contents data: Data?, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let opType = FileOperationType.modify(path: path)
+        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
+            return nil
+        }
+        
+        let operation = RemoteOperationHandle(operationType: opType, tasks: [])
+        let task = session.fpstreamTask(withHostName: baseURL!.host!, port: baseURL!.port!)
+        self.ftpLogin(task) { (error) in
+            if let error = error {
+                self.dispatch_queue.async {
+                    completionHandler?(error)
+                    self.delegateNotify(opType, error: error)
+                }
+                return
+            }
+            
+            let storeHandler = {
+                self.ftpStore(task, filePath: self.ftpPath(path), fromData: data ?? Data(), fromFile: nil, onTask: {
+                    operation.add(task: $0)
+                    $0.taskDescription = opType.json
+                }, onProgress: { bytesSent, totalSent, expectedBytes in
+                    DispatchQueue.main.async {
+                        self.delegate?.fileproviderProgress(self, operation: opType, progress: Float(Double(totalSent) / Double(expectedBytes)))
+                    }
+                }, completionHandler: { (error) in
+                    self.ftpQuit(task)
+                    self.dispatch_queue.async {
+                        completionHandler?(error)
+                        self.delegateNotify(opType, error: error)
+                    }
+                })
+            }
+            
+            if overwrite {
+                storeHandler()
+            } else {
+                self.attributesOfItem(path: path, completionHandler: { (file, erroe) in
+                    if file == nil {
+                        storeHandler()
+                    }
+                })
+            }
+        }
+        
+        return operation
+    }
+}
+
+extension FTPFileProvider {
+    /**
+     Creates a symbolic link at the specified path that points to an item at the given path.
+     This method does not traverse symbolic links contained in destination path, making it possible
+     to create symbolic links to locations that do not yet exist.
+     Also, if the final path component is a symbolic link, that link is not followed.
+     
+     - Note: Many servers does't support this functionality.
+     
+     - Parameters:
+       - symbolicLink: The file path at which to create the new symbolic link. The last component of the path issued as the name of the link.
+       - withDestinationPath: The path that contains the item to be pointed to by the link. In other words, this is the destination of the link.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+     */
+    public func create(symbolicLink path: String, withDestinationPath destPath: String, completionHandler: SimpleCompletionHandler) {
+        let opType = FileOperationType.link(link: path, target: destPath)
+        _=self.doOperation(opType, completionHandler: completionHandler)
+    }
+}
+
+extension FTPFileProvider: FileProvider { }
@@ -0,0 +1,897 @@
+//
+//  FTPHelper.swift
+//  FileProvider
+//
+//  Created by Amir Abbas Mousavian.
+//  Copyright © 2017 Mousavian. Distributed under MIT license.
+//
+
+import Foundation
+
+extension FTPFileProvider {
+    func delegateNotify(_ operation: FileOperationType, error: Error?) {
+        DispatchQueue.main.async(execute: {
+            if error == nil {
+                self.delegate?.fileproviderSucceed(self, operation: operation)
+            } else {
+                self.delegate?.fileproviderFailed(self, operation: operation)
+            }
+        })
+    }
+    
+    func readDataUntilEOF(of task: FileProviderStreamTask, minLength: Int, receivedData: Data? = nil, timeout: TimeInterval, completionHandler: @escaping (_ data: Data?, _ errror:Error?) -> Void) {
+        task.readData(ofMinLength: minLength, maxLength: 65535, timeout: timeout) { (data, eof, error) in
+            if let error = error {
+                completionHandler(nil, error)
+                return
+            }
+            
+            var receivedData = receivedData
+            if let data = data {
+                if receivedData != nil {
+                    receivedData!.append(data)
+                } else {
+                    receivedData = data
+                }
+            }
+            
+            if eof {
+                completionHandler(receivedData, nil)
+            } else {
+                self.readDataUntilEOF(of: task, minLength: 0, receivedData: receivedData, timeout: timeout, completionHandler: completionHandler)
+            }
+            
+        }
+    }
+    
+    func execute(command: String, on task: FileProviderStreamTask, minLength: Int = 4, afterSend: ((_ error: Error?) -> Void)? = nil, completionHandler: @escaping (_ response: String?, _ error: Error?) -> Void) {
+        let timeout = session.configuration.timeoutIntervalForRequest
+        let terminalcommand = command + "\r\n"
+        task.write(terminalcommand.data(using: .utf8)!, timeout: timeout) { (error) in
+            if let error = error {
+                completionHandler(nil, error)
+                return
+            }
+            afterSend?(error)
+            
+            if task.state == .suspended {
+                task.resume()
+            }
+            
+            task.readData(ofMinLength: minLength, maxLength: 1024, timeout: timeout) { (data, eof, error) in
+                if let error = error {
+                    completionHandler(nil, error)
+                    return
+                }
+                
+                if let data = data, let response = String(data: data, encoding: .utf8) {
+                    completionHandler(response.trimmingCharacters(in: CharacterSet(charactersIn: "\r\n")), nil)
+                } else {
+                    completionHandler(nil, self.throwError("", code: URLError.cannotParseResponse))
+                    return
+                }
+            }
+        }
+    }
+    
+    func ftpLogin(_ task: FileProviderStreamTask, completionHandler: @escaping (_ error: Error?) -> Void) {
+        let timeout = session.configuration.timeoutIntervalForRequest
+        if task.state == .suspended {
+            task.resume()
+        }
+        
+        let credential = self.credential
+        
+        task.readData(ofMinLength: 4, maxLength: 2048, timeout: timeout) { (data, eof, error) in
+            if let error = error {
+                completionHandler(error)
+                return
+            }
+            
+            guard let data = data, let response = String(data: data, encoding: .utf8) else {
+                completionHandler(self.throwError("", code: URLError.cannotParseResponse))
+                return
+            }
+            
+            guard response.hasPrefix("22") else {
+                let spaceIndex = response.characters.index(of: "-") ?? response.startIndex
+                let code = Int(response.substring(to: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)) ?? -1
+                let description = response.substring(from: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)
+                let error = FileProviderFTPError(code: code, path: "", errorDescription: description)
+                completionHandler(error)
+                return
+            }
+            
+            let loginHandle = {
+                self.execute(command: "USER \(credential?.user ?? "anonymous")", on: task) { (response, error) in
+                    if let error = error {
+                        completionHandler(error)
+                        return
+                    }
+                    
+                    guard let response = response else {
+                        completionHandler(self.throwError("", code: URLError.badServerResponse))
+                        return
+                    }
+                    
+                    // successfully logged in
+                    if response.hasPrefix("23") {
+                        completionHandler(nil)
+                        return
+                    }
+                    
+                    // needs password
+                    if response.hasPrefix("33") {
+                        self.execute(command: "PASS \(credential?.password ?? "fileprovider@")", on: task) { (response, error) in
+                            if response?.hasPrefix("2") ?? false {
+                                completionHandler(nil)
+                            } else {
+                                completionHandler(self.throwError("", code: URLError.userAuthenticationRequired))
+                            }
+                        }
+                        return
+                    }
+                    
+                    let spaceIndex = response.characters.index(of: "-") ?? response.startIndex
+                    let code = Int(response.substring(to: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)) ?? -1
+                    let description = response.substring(from: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)
+                    let error = FileProviderFTPError(code: code, path: "", errorDescription: description)
+                    completionHandler(error)
+                    return
+                }
+            }
+            
+            if self.baseURL?.scheme == "ftps" || self.baseURL?.port == 990 {
+                self.execute(command: "AUTH TLS", on: task, minLength: 0, completionHandler: { (response, error) in
+                    task.startSecureConnection()
+                    loginHandle()
+                })
+            } else {
+                loginHandle()
+            }
+        }
+    }
+    
+    func ftpCwd(_ task: FileProviderStreamTask, to path: String, completionHandler: @escaping (_ error: Error?) -> Void) {
+        self.execute(command: "CWD \(path)", on: task) { (response, error) in
+            if let error = error {
+                completionHandler(error)
+                return
+            }
+            
+            guard let response = response else {
+                completionHandler(self.throwError(path, code: URLError.badServerResponse))
+                return
+            }
+            
+            // successfully logged in
+            if response.hasPrefix("25") {
+                completionHandler(nil)
+            }
+            // not logged in
+            else if response.hasPrefix("55") {
+                let spaceIndex = response.characters.index(of: "-") ?? response.startIndex
+                let code = Int(response.substring(to: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)) ?? -1
+                let description = response.substring(from: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)
+                let error = FileProviderFTPError(code: code, path: "", errorDescription: description)
+                completionHandler(error)
+                return
+            }
+        }
+    }
+    
+    func ftpPassive(_ task: FileProviderStreamTask, completionHandler: @escaping (_ dataTask: FileProviderStreamTask?, _ error: Error?) -> Void) {
+        func trimmedNumber(_ s : String) -> String {
+            let characterSet = Set("+*#0123456789".characters)
+            return String(s.characters.lazy.filter(characterSet.contains))
+        }
+        
+        self.execute(command: "PASV", on: task) { (response, error) in
+            if let error = error {
+                completionHandler(nil, error)
+                return
+            }
+            
+            guard let response = response, let destString = response.components(separatedBy: " ").flatMap({ $0 }).last else {
+                completionHandler(nil, self.throwError("", code: URLError.badServerResponse))
+                return
+            }
+            
+            let destArray = destString.components(separatedBy: ",").flatMap({ UInt32(trimmedNumber($0)) })
+            guard destArray.count == 6 else {
+                completionHandler(nil, self.throwError("", code: URLError.badServerResponse))
+                return
+            }
+            
+            // first 4 elements are ip, 2 next are port, as byte
+            var host = destArray.prefix(4).flatMap({ String($0) }).joined(separator: ".")
+            let port = Int(destArray[4] << 8 + destArray[5])
+            // IPv6 workaround
+            if host == "127.555.555.555" {
+                host = self.baseURL!.host!
+            }
+            
+            let passiveTask = self.session.fpstreamTask(withHostName: host, port: port)
+            passiveTask.resume()
+            if self.baseURL?.scheme == "ftps" || self.baseURL?.port == 990 {
+                task.startSecureConnection()
+            }
+            completionHandler(passiveTask, nil)
+        }
+    }
+    
+    func ftpActive(_ task: FileProviderStreamTask, completionHandler: @escaping (_ dataTask: FileProviderStreamTask?, _ error: Error?) -> Void) {
+        var port: Int32 = 0
+        var _activeTask: FileProviderStreamTask?
+        while (_activeTask?.state ?? .suspended) == .suspended {
+            port = 32000 + Int32(arc4random_uniform(16384))
+            let service = NetService(domain: "", type: "_tcp.", name: "", port: port)
+            _activeTask = self.session.fpstreamTask(withNetService: service)
+            _activeTask?.resume()
+        }
+        guard let activeTask = _activeTask else { return }
+        if self.baseURL?.scheme == "ftps" || self.baseURL?.port == 990 {
+            task.startSecureConnection()
+        }
+        self.execute(command: "PORT \(port)", on: task) { (response, error) in
+            if let error = error {
+                activeTask.cancel()
+                completionHandler(nil, error)
+                return
+            }
+            
+            guard let response = response else {
+                completionHandler(nil, self.throwError("", code: URLError.badServerResponse))
+                return
+            }
+            
+            guard !response.hasPrefix("5") else {
+                completionHandler(nil, self.throwError("", code: URLError.cannotConnectToHost))
+                return
+            }
+            
+            completionHandler(activeTask, nil)
+        }
+    }
+    
+    func ftpDataConnect(_ task: FileProviderStreamTask, completionHandler: @escaping (_ dataTask: FileProviderStreamTask?, _ error: Error?) -> Void) {
+        if self.passiveMode {
+            self.ftpPassive(task, completionHandler: completionHandler)
+        } else {
+            self.ftpActive(task, completionHandler: completionHandler)
+        }
+    }
+    
+    func ftpRest(_ task: FileProviderStreamTask, startPosition: Int64, completionHandler: @escaping (_ error: Error?) -> Void) {
+        self.execute(command: "REST \(startPosition)", on: task) { (response, error) in
+            if let error = error {
+                completionHandler(error)
+                return
+            }
+            
+            // Successful
+            if response?.hasPrefix("35") ?? false {
+                completionHandler(nil)
+            } else {
+                let spaceIndex = response?.characters.index(of: "-") ?? response?.startIndex
+                let code = Int((response?.substring(to: spaceIndex!).trimmingCharacters(in: .whitespacesAndNewlines))!) ?? -1
+                let description = response?.substring(from: spaceIndex!).trimmingCharacters(in: .whitespacesAndNewlines)
+                let error = FileProviderFTPError(code: code, path: "", errorDescription: description)
+                completionHandler(error)
+                return
+            }
+        }
+    }
+    
+    func ftpList(_ task: FileProviderStreamTask, of path: String, useMLST: Bool, completionHandler: @escaping (_ contents: [String], _ error: Error?) -> Void) {
+        self.ftpDataConnect(task) { (dataTask, error) in
+            if let error = error {
+                completionHandler([], error)
+                return
+            }
+            
+            guard let dataTask = dataTask else {
+                completionHandler([], self.throwError(path, code: URLError.badServerResponse))
+                return
+            }
+            
+            var success = false
+            let command = useMLST ? "MLSD \(path)" : "LIST \(path)"
+            self.execute(command: command, on: task, minLength: 70, afterSend: { error in
+                // starting passive task
+                let timeout = self.session.configuration.timeoutIntervalForRequest
+                
+                DispatchQueue.global().async {
+                    var finalData = Data()
+                    var eof = false
+                    var error: Error?
+                    while !eof {
+                        let group = DispatchGroup()
+                        group.enter()
+                        dataTask.readData(ofMinLength: 0, maxLength: 65535, timeout: timeout, completionHandler: { (data, seof, serror) in
+                            if let data = data {
+                                finalData.append(data)
+                            }
+                            eof = seof
+                            error = serror
+                            group.leave()
+                        })
+                        let waitResult = group.wait(timeout: .now() + timeout)
+                        
+                        if let error = error {
+                            completionHandler([], error)
+                            return
+                        }
+                        
+                        if waitResult == .timedOut {
+                            completionHandler([], self.throwError(path, code: URLError.timedOut))
+                            return
+                        }
+                    }
+                    
+                    guard let response = String(data: finalData, encoding: .utf8) else {
+                        completionHandler([], self.throwError(path, code: URLError.badServerResponse))
+                        return
+                    }
+                    
+                    let contents = response.components(separatedBy: "\n").flatMap({ $0.trimmingCharacters(in: .whitespacesAndNewlines) })
+                    success = true
+                    completionHandler(contents, nil)
+                    return
+                }
+            }) { (response, error) in
+                if let error = error {
+                    completionHandler([], error)
+                    return
+                }
+                
+                guard let response = response else {
+                    completionHandler([], self.throwError(path, code: URLError.cannotParseResponse))
+                    return
+                }
+                
+                if response.hasPrefix("50") && useMLST {
+                    self.ftpList(task, of: path, useMLST: false, completionHandler: completionHandler)
+                    return
+                }
+                
+                if !success && !(response.hasPrefix("25") || response.hasPrefix("15")) {
+                    let spaceIndex = response.characters.index(of: " ") ?? response.startIndex
+                    let code = Int(response.substring(to: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)) ?? -1
+                    let description = response.substring(from: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)
+                    let error = FileProviderFTPError(code: code, path: path, errorDescription: description)
+
+                    self.dispatch_queue.async {
+                        completionHandler([], error)
+                    }
+                    return
+                }
+            }
+        }
+    }
+    
+    func recursiveList(path: String, useMLST: Bool, foundItemsHandler: ((_ contents: [FileObject]) -> Void)? = nil, completionHandler: @escaping (_ contents: [FileObject], _ error: Error?) -> Void) {
+        let queue = DispatchQueue(label: "test")
+        queue.async {
+            let group = DispatchGroup()
+            var result = [FileObject]()
+            var success = true
+            group.enter()
+            self.contentsOfDirectory(path: path, completionHandler: { (files, error) in
+                success = success && (error == nil)
+                if let error = error {
+                    completionHandler([], error)
+                    group.leave()
+                    return
+                }
+                
+                result.append(contentsOf: files)
+                foundItemsHandler?(files)
+                
+                let directories: [FileObject] = files.filter { $0.isDirectory }
+                for dir in directories {
+                    group.enter()
+                    self.recursiveList(path: dir.path, useMLST: useMLST, foundItemsHandler: foundItemsHandler, completionHandler: { (contents, error) in
+                        success = success && (error == nil)
+                        if let error = error {
+                            completionHandler([], error)
+                            group.leave()
+                            return
+                        }
+                        
+                        foundItemsHandler?(files)
+                        result.append(contentsOf: contents)
+                        group.leave()
+                    })
+                }
+                group.leave()
+            })
+            group.wait()
+            
+            if success {
+                self.dispatch_queue.async {
+                    completionHandler(result, nil)
+                }
+            }
+        }
+    }
+    
+    func ftpRetrieveData(_ task: FileProviderStreamTask, filePath: String, from position: Int64 = 0, length: Int = -1, onTask: ((_ task: FileProviderStreamTask) -> Void)?, onProgress: ((_ bytesReceived: Int64, _ totalReceived: Int64, _ expectedBytes: Int64) -> Void)?, completionHandler: @escaping (_ data: Data?, _ error: Error?) -> Void) {
+        
+        // Check cache
+        if useCache, let url = URL(string: filePath.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) ?? filePath, relativeTo: self.baseURL!)?.absoluteURL, let cachedResponse = self.cache?.cachedResponse(for: URLRequest(url: url)), cachedResponse.data.count > 0 {
+            dispatch_queue.async {
+                completionHandler(cachedResponse.data, nil)
+            }
+            return
+        }
+        
+        self.attributesOfItem(path: filePath) { (file, error) in
+            let totalSize = file?.size ?? -1
+            // Retreive data from server
+            self.ftpDataConnect(task) { (dataTask, error) in
+                if let error = error {
+                    completionHandler(nil, error)
+                    return
+                }
+                
+                guard let dataTask = dataTask else {
+                    completionHandler(nil, self.throwError(filePath, code: URLError.badServerResponse))
+                    return
+                }
+                
+                // Send retreive command
+                let len = 19 /* TYPE response */ + 65 + String(position).characters.count /* REST Response */ + 53 + filePath.characters.count + String(totalSize).characters.count /* RETR open response */ + 26 /* RETR Transfer complete message. */
+                self.execute(command: "TYPE I" + "\r\n" + "REST \(position)" + "\r\n" + "RETR \(filePath)", on: task, minLength: len, afterSend: { error in
+                    // starting passive task
+                    onTask?(dataTask)
+                    
+                    let timeout = self.session.configuration.timeoutIntervalForRequest
+                    DispatchQueue.global().async {
+                        var finalData = Data()
+                        var eof = false
+                        var error: Error?
+                        while !eof {
+                            let group = DispatchGroup()
+                            group.enter()
+                            dataTask.readData(ofMinLength: 0, maxLength: 65535, timeout: timeout, completionHandler: { (data, seof, serror) in
+                                if let data = data {
+                                    finalData.append(data)
+                                    onProgress?(Int64(data.count), Int64(finalData.count), totalSize)
+                                }
+                                eof = seof || (length > 0 && finalData.count >= length)
+                                if length > 0 && finalData.count > length {
+                                    finalData.count = length
+                                }
+                                error = serror
+                                group.leave()
+                            })
+                            let waitResult = group.wait(timeout: .now() + timeout)
+                            
+                            if let error = error {
+                                completionHandler(nil, error)
+                                return
+                            }
+                            
+                            if waitResult == .timedOut {
+                                completionHandler(nil, self.throwError(filePath, code: URLError.timedOut))
+                                return
+                            }
+                        }
+                        
+                        if let url = URL(string: filePath.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) ?? filePath, relativeTo: self.baseURL!)?.absoluteURL {
+                            let urlresponse = URLResponse(url: url, mimeType: nil, expectedContentLength: finalData.count, textEncodingName: nil)
+                            let cachedResponse = CachedURLResponse(response: urlresponse, data: finalData)
+                            let request = URLRequest(url: url)
+                            self.cache?.storeCachedResponse(cachedResponse, for: request)
+                        }
+                        
+                        completionHandler(finalData, nil)
+                        return
+                    }
+                }) { (response, error) in
+                    if let error = error {
+                        completionHandler(nil, error)
+                        return
+                    }
+                    
+                    guard let response = response else {
+                        completionHandler(nil, self.throwError(filePath, code: URLError.cannotParseResponse))
+                        return
+                    }
+                    
+                    if !(response.hasPrefix("1") || !response.hasPrefix("2")) {
+                        let spaceIndex = response.characters.index(of: "-") ?? response.startIndex
+                        let code = Int(response.substring(to: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)) ?? -1
+                        let description = response.substring(from: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)
+                        let error = FileProviderFTPError(code: code, path: "", errorDescription: description)
+                        
+                        self.dispatch_queue.async {
+                            completionHandler(nil, error)
+                        }
+                        return
+                    }
+                }
+            }
+        }
+    }
+    
+    func ftpRetrieveFile(_ task: FileProviderStreamTask, filePath: String, from position: Int64 = 0, length: Int = -1, onTask: ((_ task: FileProviderStreamTask) -> Void)?, onProgress: ((_ bytesReceived: Int64, _ totalReceived: Int64, _ expectedBytes: Int64) -> Void)?, completionHandler: @escaping (_ file: URL?, _ error: Error?) -> Void) {
+        let tempURL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(UUID().uuidString).appendingPathExtension("tmp")
+        
+        // Check cache
+        if useCache, let url = URL(string: filePath.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) ?? filePath, relativeTo: self.baseURL!)?.absoluteURL, let cachedResponse = self.cache?.cachedResponse(for: URLRequest(url: url)), cachedResponse.data.count > 0 {
+            dispatch_queue.async {
+                do {
+                    try cachedResponse.data.write(to: tempURL)
+                    completionHandler(tempURL, nil)
+                } catch {
+                    completionHandler(nil, error)
+                }
+                try? FileManager.default.removeItem(at: tempURL)
+            }
+            return
+        }
+        
+        self.attributesOfItem(path: filePath) { (file, error) in
+            let totalSize = file?.size ?? -1
+            // Retreive data from server
+            self.ftpDataConnect(task) { (dataTask, error) in
+                if let error = error {
+                    completionHandler(nil, error)
+                    return
+                }
+                
+                guard let dataTask = dataTask else {
+                    completionHandler(nil, self.throwError(filePath, code: URLError.badServerResponse))
+                    return
+                }
+                
+                // Send retreive command
+                let len = 19 /* TYPE response */ + 65 + String(position).characters.count /* REST Response */ + 53 + filePath.characters.count + String(totalSize).characters.count /* RETR open response */ + 26 /* RETR Transfer complete message. */
+                self.execute(command: "TYPE I"  + "\r\n" + "REST \(position)" + "\r\n" + "RETR \(filePath)", on: task, minLength: len, afterSend: { error in
+                    // starting passive task
+                    onTask?(dataTask)
+                    
+                    let timeout = self.session.configuration.timeoutIntervalForRequest
+                    DispatchQueue.global().async {
+                        var finalData = Data()
+                        var eof = false
+                        var error: Error?
+                        while !eof {
+                            let group = DispatchGroup()
+                            group.enter()
+                            dataTask.readData(ofMinLength: 0, maxLength: 65535, timeout: timeout, completionHandler: { (data, seof, serror) in
+                                if let data = data {
+                                    finalData.append(data)
+                                    onProgress?(Int64(data.count), Int64(finalData.count), totalSize)
+                                }
+                                eof = seof || (length > 0 && finalData.count >= length)
+                                if length > 0 && finalData.count > length {
+                                    finalData.count = length
+                                }
+                                error = serror
+                                group.leave()
+                            })
+                            let waitResult = group.wait(timeout: .now() + timeout)
+                            
+                            if let error = error {
+                                completionHandler(nil, error)
+                                return
+                            }
+                            
+                            if waitResult == .timedOut {
+                                error = self.throwError("", code: URLError.timedOut)
+                                completionHandler(nil, error)
+                                return
+                            }
+                        }
+                        
+                        if let url = URL(string: filePath.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) ?? filePath, relativeTo: self.baseURL!)?.absoluteURL {
+                            let urlresponse = URLResponse(url: url, mimeType: nil, expectedContentLength: finalData.count, textEncodingName: nil)
+                            let cachedResponse = CachedURLResponse(response: urlresponse, data: finalData)
+                            let request = URLRequest(url: url)
+                            self.cache?.storeCachedResponse(cachedResponse, for: request)
+                        }
+                        
+                        self.dispatch_queue.async {
+                            do {
+                                try finalData.write(to: tempURL)
+                                completionHandler(tempURL, nil)
+                            } catch {
+                                completionHandler(nil, error)
+                            }
+                            try? FileManager.default.removeItem(at: tempURL)
+                        }
+                        return
+                    }
+                }) { (response, error) in
+                    if let error = error {
+                        completionHandler(nil, error)
+                        return
+                    }
+                    
+                    guard let response = response else {
+                        completionHandler(nil, self.throwError(filePath, code: URLError.cannotParseResponse))
+                        return
+                    }
+                    
+                    if !(response.hasPrefix("1") || response.hasPrefix("2")) {
+                        let spaceIndex = response.characters.index(of: "-") ?? response.startIndex
+                        let code = Int(response.substring(to: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)) ?? -1
+                        let description = response.substring(from: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)
+                        let error = FileProviderFTPError(code: code, path: "", errorDescription: description)
+                        
+                        self.dispatch_queue.async {
+                            completionHandler(nil, error)
+                        }
+                        return
+                    }
+                }
+            }
+        }
+    }
+    
+    func ftpStore(_ task: FileProviderStreamTask, filePath: String, fromData: Data?, fromFile: URL?, onTask: ((_ task: FileProviderStreamTask) -> Void)?,  onProgress: ((_ bytesSent: Int64, _ totalSent: Int64, _ expectedBytes: Int64) -> Void)?, completionHandler: @escaping (_ error: Error?) -> Void) {
+        
+        self.ftpDataConnect(task) { (dataTask, error) in
+            if let error = error {
+                completionHandler(error)
+                return
+            }
+            
+            guard let dataTask = dataTask else {
+                completionHandler(self.throwError(filePath, code: URLError.badServerResponse))
+                return
+            }
+            
+            // Send retreive command
+            let len = 17 /* */
+            self.execute(command: "TYPE I"  + "\r\n" + "REST 0"  + "\r\n" + "STOR \(filePath)", on: task, minLength: 90 + filePath.characters.count, afterSend: { error in
+                // starting passive task
+                let timeout = self.session.configuration.timeoutIntervalForRequest
+                if self.baseURL?.scheme == "ftps" || self.baseURL?.port == 990 {
+                    task.startSecureConnection()
+                }
+                onTask?(dataTask)
+                
+                DispatchQueue.global().async {
+                    var error: Error?
+                    let chunkSize = 65536
+                    
+                    guard let size: Int64 = (fromData != nil ? Int64(fromData!.count) : nil) ?? fromFile?.fileSize else { return }
+                    var fileHandle: FileHandle?
+                    if let file = fromFile {
+                        fileHandle = FileHandle(forReadingAtPath: file.path)
+                    }
+                    defer {
+                        fileHandle?.closeFile()
+                    }
+                    var eof = false
+                    var sent: Int64 = 0
+                    let group = DispatchGroup()
+                    while !eof {
+                        group.enter()
+                        
+                        let subdata: Data
+                        if let data = fromData {
+                            let endIndex = min(data.count, Int(sent) + chunkSize)
+                            eof = endIndex == data.count
+                            subdata = data.subdata(in: Int(sent)..<endIndex)
+                        }else if let fileHandle = fileHandle {
+                            subdata = fileHandle.readData(ofLength: chunkSize)
+                            eof = Int64(fileHandle.offsetInFile) == size
+                        } else {
+                            return
+                        }
+                        if subdata.count == 0 { continue }
+                        
+                        dataTask.write(subdata, timeout: timeout, completionHandler: { (serror) in
+                            error = serror
+                            sent += Int64(subdata.count)
+                            onProgress?(Int64(subdata.count), sent, size)
+                            group.leave()
+                        })
+                    }
+                    let waitResult = group.wait(timeout: .now() + timeout)
+                    
+                    if let error = error {
+                        completionHandler(error)
+                        return
+                    }
+                    
+                    if waitResult == .timedOut {
+                        error = self.throwError(fromFile?.relativePath ?? filePath, code: URLError.timedOut)
+                        completionHandler(error)
+                        return
+                    }
+                    
+                    dataTask.closeRead()
+                    dataTask.closeWrite()
+                    completionHandler(nil)
+                    return
+                }
+            }) { (response, error) in
+                if let error = error {
+                    completionHandler(error)
+                    return
+                }
+                
+                guard let response = response else {
+                    completionHandler(self.throwError(filePath, code: URLError.cannotParseResponse))
+                    return
+                }
+                
+                if !(response.hasPrefix("1") || response.hasPrefix("2")) {
+                    let spaceIndex = response.characters.index(of: "-") ?? response.startIndex
+                    let code = Int(response.substring(to: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)) ?? -1
+                    let description = response.substring(from: spaceIndex).trimmingCharacters(in: .whitespacesAndNewlines)
+                    let error = FileProviderFTPError(code: code, path: "", errorDescription: description)
+                    
+                    self.dispatch_queue.async {
+                        completionHandler(error)
+                    }
+                    return
+                }
+            }
+        }
+    }
+    
+    func ftpQuit(_ task: FileProviderStreamTask) {
+        self.execute(command: "QUIT", on: task) { (_, _) in
+            //task.closeRead()
+            //task.closeWrite()
+        }
+    }
+    
+    func ftpPath(_ apath: String) -> String {
+        var path = apath.isEmpty ? self.currentPath : apath
+        
+        // path of base url should be concreted into file path!
+        path = baseURL!.appendingPathComponent(path).path
+        
+        // Fixing slashes
+        if !path.hasPrefix("/") {
+            path = "/" + path
+        }
+        if path.hasSuffix("/"){
+            path.characters.removeLast()
+        }
+        
+        if path.isEmpty {
+            path = "/"
+        }
+        
+        return path
+    }
+    
+    func parseUnixList(_ text: String, in path: String) -> FileObject? {
+        let gregorian = Calendar(identifier: .gregorian)
+        let nearDateFormatter = DateFormatter()
+        nearDateFormatter.calendar = gregorian
+        nearDateFormatter.locale = Locale(identifier: "en_US_POSIX")
+        nearDateFormatter.dateFormat = "MMM dd hh:ss yyyy"
+        let farDateFormatter = DateFormatter()
+        farDateFormatter.calendar = gregorian
+        farDateFormatter.locale = Locale(identifier: "en_US_POSIX")
+        farDateFormatter.dateFormat = "MMM dd yyyy"
+        let thisYear = gregorian.component(.year, from: Date())
+        
+        let components = text.components(separatedBy: " ").flatMap { $0.isEmpty ? nil : $0 }
+        guard components.count >= 9 else { return nil }
+        let posixPermission = components[0]
+        let linksCount = Int(components[1]) ?? 0
+        //let owner = components[2]
+        //let groupOwner = components[3]
+        let size = Int64(components[4]) ?? -1
+        let date = components[5..<8].joined(separator: " ")
+        let name = components[8..<components.count].joined(separator: " ")
+        
+        guard name != "." && name != ".." else { return nil }
+        var path = (path as NSString).appendingPathComponent(name)
+        if path.hasPrefix("/") {
+            path.characters.removeFirst()
+        }
+        
+        let file = FileObject(url: url(of: path), name: name, path: path)
+        switch String(posixPermission.characters.first!) {
+        case "d": file.type = .directory
+        case "l": file.type = .symbolicLink
+        default:  file.type = .regular
+        }
+        file.isReadOnly = !posixPermission.contains("w")
+        file.size = file.isDirectory ? -1 : size
+        file.allValues[.linkCountKey] = linksCount
+        
+        if let parsedDate = nearDateFormatter.date(from: date + " " + String(thisYear)) {
+            if parsedDate > Date() {
+                file.modifiedDate = gregorian.date(byAdding: .year, value: -1, to: parsedDate)
+            } else {
+                file.modifiedDate = parsedDate
+            }
+        } else if let parsedDate = farDateFormatter.date(from: date) {
+            file.modifiedDate = parsedDate
+        }
+        
+        return file
+    }
+    
+    func parseMLST(_ text: String, in path: String) -> FileObject? {
+        var components = text.components(separatedBy: ";").flatMap { $0.isEmpty ? nil : $0 }
+        guard components.count > 1 else { return nil }
+        
+        let nameOrPath = components.removeLast().trimmingCharacters(in: .whitespacesAndNewlines)
+        var correctedPath: String
+        let name: String
+        if nameOrPath.hasPrefix("/") {
+            correctedPath = nameOrPath.replacingOccurrences(of: baseURL!.path, with: "", options: .anchored)
+            name = (nameOrPath as NSString).lastPathComponent
+        } else {
+            name = nameOrPath
+            correctedPath = (path as NSString).appendingPathComponent(nameOrPath)
+        }
+        if correctedPath.hasPrefix("/") {
+            correctedPath.characters.removeFirst()
+        }
+        
+        var attributes = [String: String]()
+        for component in components {
+            let keyValue = component.components(separatedBy: "=") .flatMap { $0.isEmpty ? nil : $0 }
+            guard keyValue.count >= 2, !keyValue[0].isEmpty else { continue }
+            attributes[keyValue[0].lowercased()] = keyValue.dropFirst().joined(separator: "=")
+        }
+        
+        let file = FileObject(url: url(of: correctedPath), name: name, path: correctedPath)
+        let dateFormatter = DateFormatter()
+        dateFormatter.calendar = Calendar(identifier: .gregorian)
+        dateFormatter.locale = Locale(identifier: "en_US_POSIX")
+        dateFormatter.dateFormat = "yyyyMMddhhmmss"
+        for (key, attribute) in attributes {
+            switch key {
+            case "type":
+                switch attribute.lowercased() {
+                case "file": file.type = .regular
+                case "dir": file.type = .directory
+                case "link": file.type = .symbolicLink
+                case "os.unix=block": file.type = .blockSpecial
+                case "cdir", "pdir": return nil // . and .. files are redundant in listing
+                default: file.type = .unknown
+                }
+                
+            case "unique":
+                file.allValues[.fileResourceIdentifierKey] = attribute
+                
+            case "modify":
+                file.modifiedDate = dateFormatter.date(from: attribute)
+            
+            case "create":
+                file.creationDate = dateFormatter.date(from: attribute)
+                
+            case "perm":
+                file.allValues[.isReadableKey] = attribute.contains("r") || attribute.contains("l")
+                file.allValues[.isWritableKey] = attribute.contains("w") || attribute.contains("a")
+                
+            case "size":
+                file.size = Int64(attribute) ?? -1
+                
+            case "media-type":
+                file.allValues[.mimeTypeKey] = attribute
+                
+            default:
+                break
+            }
+        }
+        
+        return file
+    }
+}
+
+/// Contains error code and description returned by FTP/S provider.
+public struct FileProviderFTPError: Error {
+    /// HTTP status code returned for error by server.
+    public let code: Int
+    /// Path of file/folder casued that error
+    public let path: String
+    /// Contents returned by server as error description
+    public let errorDescription: String?
+}
@@ -8,119 +8,111 @@

 import Foundation

-/// Containts path and attributes of a file or resource.
-open class FileObject {
-    open internal(set) var allValues: [String: Any]
+/// Containts path, url and attributes of a file or resource.
+open class FileObject: Equatable {
+    /// A `Dictionary` contains file information,  using `URLResourceKey` keys.
+    open internal(set) var allValues: [URLResourceKey: Any]
    
-    internal init(allValues: [String: Any]) {
+    internal init(allValues: [URLResourceKey: Any]) {
        self.allValues = allValues
    }
    
    internal init(url: URL, name: String, path: String) {
-        self.allValues = [String: Any]()
+        self.allValues = [URLResourceKey: Any]()
        self.url = url
        self.name = name
        self.path = path
    }
    
-    /// url to access the resource, not supported by Dropbox provider
-    @available(*, deprecated, message: "Use FileObject.url.absoluteURL instead.")
-    open var absoluteURL: URL? {
-        return url?.absoluteURL
-    }
-    
+    /// URL to access the resource, can be a relative URL against base URL.
+    /// not supported by Dropbox provider.
    open internal(set) var url: URL? {
        get {
-            return allValues["NSURLFileURLKey"] as? URL
+            return allValues[.fileURLKey] as? URL
        }
        set {
-            allValues["NSURLFileURLKey"] = newValue
+            allValues[.fileURLKey] = newValue
        }
    }
    
    /// Name of the file, usually equals with the last path component
    open internal(set) var name: String {
        get {
-            return allValues[URLResourceKey.nameKey.rawValue] as! String
+            return allValues[.nameKey] as! String
        }
        set {
-            allValues[URLResourceKey.nameKey.rawValue] = newValue
+            allValues[.nameKey] = newValue
        }
    }
    
    /// Relative path of file object
    open internal(set) var path: String {
        get {
-            return allValues[URLResourceKey.pathKey.rawValue] as! String
+            return allValues[.pathKey] as! String
        }
        set {
-            allValues[URLResourceKey.pathKey.rawValue] = newValue
+            allValues[.pathKey] = newValue
        }
    }
    
    /// Size of file on disk, return -1 for directories.
    open internal(set) var size: Int64 {
        get {
-            return allValues[URLResourceKey.fileSizeKey.rawValue] as? Int64 ?? -1
+            return allValues[.fileSizeKey] as? Int64 ?? -1
        }
        set {
-            allValues[URLResourceKey.fileSizeKey.rawValue] = newValue
+            allValues[.fileSizeKey] = newValue
        }
    }
    
    /// The time contents of file has been created, returns nil if not set
    open internal(set) var creationDate: Date? {
        get {
-            return allValues[URLResourceKey.creationDateKey.rawValue] as? Date
+            return allValues[.creationDateKey] as? Date
        }
        set {
-            allValues[URLResourceKey.creationDateKey.rawValue] = newValue
+            allValues[.creationDateKey] = newValue
        }
    }
    
    /// The time contents of file has been modified, returns nil if not set
    open internal(set) var modifiedDate: Date? {
        get {
-            return allValues[URLResourceKey.contentModificationDateKey.rawValue] as? Date
+            return allValues[.contentModificationDateKey] as? Date
        }
        set {
-            allValues[URLResourceKey.contentModificationDateKey.rawValue] = newValue
+            allValues[.contentModificationDateKey] = newValue
        }
    }
    
    /// return resource type of file, usually directory, regular or symLink
    open internal(set) var type: URLFileResourceType? {
        get {
-            return allValues[URLResourceKey.fileResourceTypeKey.rawValue] as? URLFileResourceType
+            return allValues[.fileResourceTypeKey] as? URLFileResourceType
        }
        set {
-            allValues[URLResourceKey.fileResourceTypeKey.rawValue] = newValue
+            allValues[.fileResourceTypeKey] = newValue
        }
    }
    
-    @available(*, deprecated, message: "Use FileObject.type property instead.")
-    open var fileType: URLFileResourceType? {
-        return self.type
-    }
-    
    /// File is hidden either because begining with dot or filesystem flags
    /// Setting this value on a file begining with dot has no effect
    open internal(set) var isHidden: Bool {
        get {
-            return allValues[URLResourceKey.isHiddenKey.rawValue] as? Bool ?? false
+            return allValues[.isHiddenKey] as? Bool ?? false
        }
        set {
-            allValues[URLResourceKey.isHiddenKey.rawValue] = newValue
+            allValues[.isHiddenKey] = newValue
        }
    }
    
    /// File can not be written
    open internal(set) var isReadOnly: Bool {
        get {
-            return !(allValues[URLResourceKey.isWritableKey.rawValue] as? Bool ?? true)
+            return !(allValues[.isWritableKey] as? Bool ?? true)
        }
        set {
-            allValues[URLResourceKey.isWritableKey.rawValue] = !newValue
+            allValues[.isWritableKey] = !newValue
        }
    }
    
@@ -138,37 +130,67 @@ open class FileObject {
    open var isSymLink: Bool {
        return self.type == .symbolicLink
    }
-}
-
-internal func resolve(dateString: String) -> Date? {
-    let dateFor: DateFormatter = DateFormatter()
-    dateFor.locale = Locale(identifier: "en_US")
-    dateFor.dateFormat = "yyyy'-'MM'-'dd'T'HH':'mm':'ssZ"
-    if let rfc3339 = dateFor.date(from: dateString) {
-        return rfc3339
-    }
-    dateFor.dateFormat = "EEE',' dd' 'MMM' 'yyyy HH':'mm':'ss z"
-    if let rfc1123 = dateFor.date(from: dateString) {
-        return rfc1123
-    }
-    dateFor.dateFormat = "EEEE',' dd'-'MMM'-'yy HH':'mm':'ss z"
-    if let rfc850 = dateFor.date(from: dateString) {
-        return rfc850
-    }
-    dateFor.dateFormat = "EEE MMM d HH':'mm':'ss yyyy"
-    if let asctime = dateFor.date(from: dateString) {
-        return asctime
+    
+    /// Check `FileObject` equality
+    public static func ==(lhs: FileObject, rhs: FileObject) -> Bool {
+        if rhs === lhs {
+            return true
+        }
+        if type(of: lhs) != type(of: rhs) {
+            return false
+        }
+        if let rurl = rhs.url, let lurl = lhs.url {
+            return rurl == lurl
+        }
+        return rhs.path == lhs.path && rhs.size == lhs.size && rhs.modifiedDate == lhs.modifiedDate
    }
    
-    return nil
-}
-
-internal func rfc3339utc(of date:Date) -> String {
-    let fm = DateFormatter()
-    fm.dateFormat = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'Z'"
-    fm.timeZone = TimeZone(identifier:"UTC")
-    fm.locale = Locale(identifier:"en_US_POSIX")
-    return fm.string(from:date)
+    internal func mapPredicate() -> [String: Any] {
+        let mapDict: [URLResourceKey: String] = [.fileURLKey: "url", .nameKey: "name", .pathKey: "path", .fileSizeKey: "filesize", .creationDateKey: "creationDate",
+                                                 .contentModificationDateKey: "modifiedDate", .isHiddenKey: "isHidden", .isWritableKey: "isWritable", .serverDateKey: "serverDate", .entryTagKey: "entryTag", .mimeTypeKey: "mimeType"]
+        let typeDict: [URLFileResourceType: String] = [.directory: "directory", .regular: "regular", .symbolicLink: "symbolicLink", .unknown: "unknown"]
+        var result = [String: Any]()
+        for (key, value) in allValues {
+            if let convertkey = mapDict[key] {
+                result[convertkey] = value
+            }
+        }
+        result["eTag"] = result["entryTag"]
+        result["isReadOnly"] = self.isReadOnly
+        result["isDirectory"] = self.isDirectory
+        result["isRegularFile"] = self.isRegularFile
+        result["isSymLink"] = self.isSymLink
+        result["type"] = typeDict[self.type ?? .unknown] ?? "unknown"
+        return result
+    }
+    
+    /// Converts macOS spotlight query for searching files to a query that can be used for `searchFiles()` method
+    static public func convertPredicate(fromSpotlight query: NSPredicate) -> NSPredicate {
+        let mapDict: [String: URLResourceKey] = [NSMetadataItemURLKey: .fileURLKey, NSMetadataItemFSNameKey: .nameKey, NSMetadataItemPathKey: .pathKey,
+                                                 NSMetadataItemFSSizeKey: .fileSizeKey, NSMetadataItemFSCreationDateKey: .creationDateKey,
+                                                 NSMetadataItemFSContentChangeDateKey: .contentModificationDateKey, "kMDItemFSInvisible": .isHiddenKey, "kMDItemFSIsWriteable": .isWritableKey, "kMDItemKind": .mimeTypeKey]
+        
+        if let cQuery = query as? NSCompoundPredicate {
+            let newSub = cQuery.subpredicates.map { convertPredicate(fromSpotlight: $0 as! NSPredicate) }
+            switch cQuery.compoundPredicateType {
+            case .and: return NSCompoundPredicate(andPredicateWithSubpredicates: newSub)
+            case .not: return NSCompoundPredicate(notPredicateWithSubpredicate: newSub[0])
+            case .or:  return NSCompoundPredicate(orPredicateWithSubpredicates: newSub)
+            }
+        } else if let cQuery = query as? NSComparisonPredicate {
+            var newLeft = cQuery.leftExpression
+            var newRight = cQuery.rightExpression
+            if newLeft.expressionType == .keyPath, let newKey = mapDict[newLeft.keyPath] {
+                newLeft = NSExpression(forKeyPath: newKey.rawValue)
+            }
+            if newRight.expressionType == .keyPath, let newKey = mapDict[newRight.keyPath] {
+                newRight = NSExpression(forKeyPath: newKey.rawValue)
+            }
+            return NSComparisonPredicate(leftExpression: newLeft, rightExpression: newRight, modifier: cQuery.comparisonPredicateModifier, type: cQuery.predicateOperatorType, options: cQuery.options)
+        } else {
+            return query
+        }
+    }
 }

 /// Sorting FileObject array by given criteria, **not thread-safe**
@@ -215,13 +237,19 @@ public struct FileObjectSorting {
    public static let createdAscending = FileObjectSorting(type: .creationDate, ascending: true)
    public static let createdDesceding = FileObjectSorting(type: .creationDate, ascending: false)
    
+    /// Initializes a `FileObjectSorting` allows to sort an `Array` of `FileObject`.
+    ///
+    /// - Parameters:
+    ///   - type: Determines to sort based on which file property.
+    ///   - ascending: `true` of resulting `Array` is ascending
+    ///   - isDirectoriesFirst: Puts directoris on the top of resulting `Array`.
    public init (type: SortType, ascending: Bool = true, isDirectoriesFirst: Bool = false) {
        self.sortType = type
        self.ascending = ascending
        self.isDirectoriesFirst = isDirectoriesFirst
    }
    
-    /// Sorts array of FileObjects by criterias set in properties
+    /// Sorts array of `FileObject`s by criterias set in attributes.
    public func sort(_ files: [FileObject]) -> [FileObject] {
        return files.sorted {
            if isDirectoriesFirst {
@@ -257,52 +285,3 @@ public struct FileObjectSorting {
        }
    }
 }
-
-extension Array where Element: FileObject {
-    public func sorted(by type: FileObjectSorting.SortType, ascending: Bool = true, isDirectoriesFirst: Bool = false) -> [Element] {
-        let sorting = FileObjectSorting(type: type, ascending: ascending, isDirectoriesFirst: isDirectoriesFirst)
-        return sorting.sort(self) as! [Element]
-    }
-    
-    public mutating func sorted(by type: FileObjectSorting.SortType, ascending: Bool = true, isDirectoriesFirst: Bool = false) {
-        self = self.sorted(by: type, ascending: ascending, isDirectoriesFirst: isDirectoriesFirst)
-    }
-}
-
-extension URLFileResourceType {
-    public init(fileTypeValue: FileAttributeType) {
-        switch fileTypeValue {
-        case FileAttributeType.typeCharacterSpecial: self = .characterSpecial
-        case FileAttributeType.typeDirectory: self = .directory
-        case FileAttributeType.typeBlockSpecial: self = .blockSpecial
-        case FileAttributeType.typeRegular: self = .regular
-        case FileAttributeType.typeSymbolicLink: self = .symbolicLink
-        case FileAttributeType.typeSocket: self = .socket
-        case FileAttributeType.typeUnknown: self = .unknown
-        default: self = .unknown
-        }
-    }
-}
-
-internal extension URL {
-    var uw_scheme: String {
-        return self.scheme ?? ""
-    }
-}
-
-internal func jsonToDictionary(_ jsonString: String) -> [String: AnyObject]? {
-    guard let data = jsonString.data(using: .utf8) else {
-        return nil
-    }
-    if let dic = try? JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions()) as? [String: AnyObject] {
-        return dic
-    }
-    return nil
-}
-
-internal func dictionaryToJSON(_ dictionary: [String: AnyObject]) -> String? {
-    if let data = try? JSONSerialization.data(withJSONObject: dictionary, options: JSONSerialization.WritingOptions()) {
-        return String(data: data, encoding: .utf8)
-    }
-    return nil
-}
@@ -0,0 +1,228 @@
+//
+//  FileProviderExtensions.swift
+//  FileProvider
+//
+//  Created by Amir Abbas on 12/27/1395 AP.
+//
+//
+
+import Foundation
+
+extension Array where Element: FileObject {
+    /// Returns a sorted array of `FileObject`s by criterias set in attributes.
+    public func sort(by type: FileObjectSorting.SortType, ascending: Bool = true, isDirectoriesFirst: Bool = false) -> [Element] {
+        let sorting = FileObjectSorting(type: type, ascending: ascending, isDirectoriesFirst: isDirectoriesFirst)
+        return sorting.sort(self) as! [Element]
+    }
+    
+    /// Sorts array of `FileObject`s by criterias set in attributes.
+    public mutating func sorted(by type: FileObjectSorting.SortType, ascending: Bool = true, isDirectoriesFirst: Bool = false) {
+        self = self.sort(by: type, ascending: ascending, isDirectoriesFirst: isDirectoriesFirst)
+    }
+}
+
+extension URLFileResourceType {
+    /// Returns corresponding `URLFileResourceType` of a `FileAttributeType` value
+    public init(fileTypeValue: FileAttributeType) {
+        switch fileTypeValue {
+        case FileAttributeType.typeCharacterSpecial: self = .characterSpecial
+        case FileAttributeType.typeDirectory: self = .directory
+        case FileAttributeType.typeBlockSpecial: self = .blockSpecial
+        case FileAttributeType.typeRegular: self = .regular
+        case FileAttributeType.typeSymbolicLink: self = .symbolicLink
+        case FileAttributeType.typeSocket: self = .socket
+        case FileAttributeType.typeUnknown: self = .unknown
+        default: self = .unknown
+        }
+    }
+}
+
+internal extension URLResourceKey {
+    static let fileURLKey = URLResourceKey(rawValue: "NSURLFileURLKey")
+    static let serverDateKey = URLResourceKey(rawValue: "NSURLServerDateKey")
+    static let entryTagKey = URLResourceKey(rawValue: "NSURLEntryTagKey")
+    static let mimeTypeKey = URLResourceKey(rawValue: "NSURLMIMETypeIdentifierKey")
+    
+    @available(*, deprecated, renamed: "fileURLKey")
+    static let fileURL = fileURLKey
+    @available(*, deprecated, renamed: "serverDateKey")
+    static let serverDate = serverDateKey
+    @available(*, deprecated, renamed: "entryTagKey")
+    static let entryTag = entryTagKey
+    @available(*, deprecated, renamed: "mimeTypeKey")
+    static let mimeType = mimeTypeKey
+}
+
+internal extension URL {
+    var uw_scheme: String {
+        return self.scheme ?? ""
+    }
+    
+    var fileIsDirectory: Bool {
+        return (try? self.resourceValues(forKeys: [.isDirectoryKey]))?.isDirectory ?? false
+    }
+    
+    var fileSize: Int64 {
+        return Int64((try? self.resourceValues(forKeys: [.fileSizeKey]))?.fileSize ?? -1)
+    }
+    
+    var fileExists: Bool {
+        return self.isFileURL && FileManager.default.fileExists(atPath: self.path)
+    }
+}
+
+internal extension Data {
+    internal var isPDF: Bool {
+        return self.count > 4 && self.scanString(length: 4, using: .ascii) == "%PDF"
+    }
+    
+    init? (jsonDictionary dictionary: [String: AnyObject]) {
+        guard let data = try? JSONSerialization.data(withJSONObject: dictionary, options: []) else {
+            return nil
+        }
+        self = data
+    }
+    
+    func deserializeJSON() -> [String: AnyObject]? {
+        if let dic = try? JSONSerialization.jsonObject(with: self, options: []) as? [String: AnyObject] {
+            return dic
+        }
+        return nil
+    }
+    
+    init<T>(value: T) {
+        var value = value
+        self = Data(buffer: UnsafeBufferPointer(start: &value, count: 1))
+    }
+    
+    func scanValue<T>() -> T? {
+        guard MemoryLayout<T>.size <= self.count else { return nil }
+        return self.withUnsafeBytes { $0.pointee }
+    }
+    
+    func scanValue<T>(start: Int) -> T? {
+        let length = MemoryLayout<T>.size
+        guard self.count >= start + length else { return nil }
+        return self.subdata(in: start..<start+length).withUnsafeBytes { $0.pointee }
+    }
+    
+    func scanString(start: Int = 0, length: Int, using encoding: String.Encoding = .utf8) -> String? {
+        guard self.count >= start + length else { return nil }
+        return String(data: self.subdata(in: start..<start+length), encoding: encoding)
+    }
+    
+    static func mapMemory<T, U>(from: T) -> U? {
+        guard MemoryLayout<T>.size >= MemoryLayout<U>.size else { return nil }
+        let data = Data(value: from)
+        return data.scanValue()
+    }
+}
+
+internal extension String {
+    init? (jsonDictionary: [String: AnyObject]) {
+        guard let data = Data(jsonDictionary: jsonDictionary) else {
+            return nil
+        }
+        self.init(data: data, encoding: .utf8)
+    }
+    
+    func deserializeJSON(using encoding: String.Encoding = .utf8) -> [String: AnyObject]? {
+        guard let data = self.data(using: encoding) else {
+            return nil
+        }
+        return data.deserializeJSON()
+    }
+}
+
+internal extension TimeInterval {
+    internal var formatshort: String {
+        var result = "0:00"
+        if self < TimeInterval(Int32.max) {
+            result = ""
+            var time = DateComponents()
+            time.hour   = Int(self / 3600)
+            time.minute = Int((self.truncatingRemainder(dividingBy: 3600)) / 60)
+            time.second = Int(self.truncatingRemainder(dividingBy: 60))
+            let formatter = NumberFormatter()
+            formatter.paddingCharacter = "0"
+            formatter.minimumIntegerDigits = 2
+            formatter.maximumFractionDigits = 0
+            let formatterFirst = NumberFormatter()
+            formatterFirst.maximumFractionDigits = 0
+            if time.hour! > 0 {
+                result = "\(formatterFirst.string(from: NSNumber(value: time.hour!))!):\(formatter.string(from: NSNumber(value: time.minute!))!):\(formatter.string(from: NSNumber(value: time.second!))!)"
+            } else {
+                result = "\(formatterFirst.string(from: NSNumber(value: time.minute!))!):\(formatter.string(from: NSNumber(value: time.second!))!)"
+            }
+        }
+        result = result.trimmingCharacters(in: CharacterSet(charactersIn: ": "))
+        return result
+    }
+}
+
+extension Date {
+   init?(rfcString: String) {
+        let dateFor: DateFormatter = DateFormatter()
+        dateFor.locale = Locale(identifier: "en_US")
+        dateFor.dateFormat = "yyyy'-'MM'-'dd'T'HH':'mm':'ssZ"
+        if let rfc3339 = dateFor.date(from: rfcString) {
+            self = rfc3339
+            return
+        }
+        dateFor.dateFormat = "EEE',' dd' 'MMM' 'yyyy HH':'mm':'ss z"
+        if let rfc1123 = dateFor.date(from: rfcString) {
+            self = rfc1123
+             return
+        }
+        dateFor.dateFormat = "EEEE',' dd'-'MMM'-'yy HH':'mm':'ss z"
+        if let rfc850 = dateFor.date(from: rfcString) {
+            self = rfc850
+             return
+        }
+        dateFor.dateFormat = "EEE MMM d HH':'mm':'ss yyyy"
+        if let asctime = dateFor.date(from: rfcString) {
+            self = asctime
+             return
+        }
+        
+        return nil
+    }
+    
+    internal func rfc3339utc() -> String {
+        let fm = DateFormatter()
+        fm.dateFormat = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'Z'"
+        fm.timeZone = TimeZone(identifier: "UTC")
+        fm.locale = Locale(identifier: "en_US_POSIX")
+        return fm.string(from: self)
+    }
+}
+
+extension NSPredicate {
+    func findValue(forKey key: String?, operator op: NSComparisonPredicate.Operator? = nil) -> Any? {
+        let val = findAllValues(forKey: key).lazy.filter { (op == nil || $0.operator == op!) && !$0.not }
+        return val.first?.value
+    }
+    
+    func findAllValues(forKey key: String?) -> [(value: Any, operator: NSComparisonPredicate.Operator, not: Bool)] {
+        if let cQuery = self as? NSCompoundPredicate {
+            let find = cQuery.subpredicates.flatMap { ($0 as! NSPredicate).findAllValues(forKey: key) }
+            if cQuery.compoundPredicateType == .not {
+                return find.map { return ($0.value, $0.operator, !$0.not) }
+            }
+            return find
+        } else if let cQuery = self as? NSComparisonPredicate {
+            if cQuery.leftExpression.expressionType == .keyPath, key == nil || cQuery.leftExpression.keyPath == key!, let const = cQuery.rightExpression.constantValue {
+                return [(value: const, operator: cQuery.predicateOperatorType, false)]
+            }
+            if cQuery.rightExpression.expressionType == .keyPath, key == nil || cQuery.rightExpression.keyPath == key!, let const = cQuery.leftExpression.constantValue {
+                return [(value: const, operator: cQuery.predicateOperatorType, false)]
+            }
+            return []
+        } else {
+            return []
+        }
+    }
+}
+
+extension URLError.Code: FoundationErrorEnum {}
+extension CocoaError.Code: FoundationErrorEnum {}
@@ -8,36 +8,69 @@

 import Foundation

-open class LocalFileProvider: FileProvider, FileProviderMonitor {
-    open static let type: String = "Local"
-    open var isPathRelative: Bool
+/**
+ This provider class allows interacting with local files placed in user disk. It also allows an
+ easy way to use `NSFileCoordintaing` to coordinate read and write when neccessary.
+ 
+ it uses `FileManager` foundation class with some additions like searching and reading a portion of file.
+ */
+open class LocalFileProvider: FileProvider, FileProviderMonitor, FileProvideUndoable {
+    open class var type: String { return "Local" }
    open fileprivate(set) var baseURL: URL?
    open var currentPath: String
    open var dispatch_queue: DispatchQueue
    open var operation_queue: OperationQueue
    open weak var delegate: FileProviderDelegate?
-    open internal(set) var credential: URLCredential?
-        
+    open var credential: URLCredential?
+    
+    /// Underlying `FileManager` object for listing and metadata fetching.
    open private(set) var fileManager = FileManager()
+    /// Underlying `FileManager` object for operationa like copying, moving, etc.
    open private(set) var opFileManager = FileManager()
    fileprivate var fileProviderManagerDelegate: LocalFileProviderManagerDelegate? = nil
    
-    /// Forces file operations to use NSFileCoordinating, should be set true if:
-    /// - Files are on ubiquity(iCloud) container
-    /// - Multiple processes are accessing same file, recommended always in macOS and when using app extensions in iOS/tvOS (shared container)
+    open var undoManager: UndoManager? = nil
+    
+    /**
+     Forces file operations to use `NSFileCoordinating`, should be set `true` if:
+     - Files are on ubiquity (iCloud) container.
+     - Multiple processes are accessing same file, recommended when accessing a shared/public 
+     user document in macOS and when using app extensions in iOS/tvOS (shared container).
+     
+     By default it's `true` when using iCloud or shared container (App Group) initializers,
+     otherwise it's `false` to accelerate operations.
+    */
    open var isCoorinating: Bool
    
-    /// default values are `directory: .documentDirectory, domainMask: .userDomainMask`
-    public convenience init (directory: FileManager.SearchPathDirectory = .documentDirectory, domainMask: FileManager.SearchPathDomainMask = .userDomainMask) {
+    /**
+     Initializes provider for the specified common directory in the requested domains.
+     default values are `directory: .documentDirectory, domainMask: .userDomainMask`.
+     
+     - Parameters:
+     - for: The search path directory. The supported values are described in `FileManager.SearchPathDirectory`.
+     - in: Base locations for directory to search. The value for this parameter is one or more of the constants described in `FileManager.SearchPathDomainMask`.
+     */
+    public convenience init (for directory: FileManager.SearchPathDirectory = .documentDirectory, in domainMask: FileManager.SearchPathDomainMask = .userDomainMask) {
        self.init(baseURL: FileManager.default.urls(for: directory, in: domainMask).first!)
    }
    
-    public convenience init ? (sharedContainerId: String, directory: FileManager.SearchPathDirectory = .userDirectory) {
+    /**
+     Failable initializer for the specified shared container directory, allows data and files to be shared among app
+     and extensions regarding sandbox requirements. Container ID is same with app group specified in project `Capabilities`
+     tab under `App Group` item. If you don't have enough privilage to access container or the app group imply does't exist,
+     initialing will fail.
+     default values are `directory: .documentDirectory`.
+    
+     - Parameters:
+       - sharedContainerId: Same with `App Group` identifier defined in project settings.
+       - directory: The search path directory. The supported values are described in `FileManager.SearchPathDirectory`.
+    */
+    public convenience init? (sharedContainerId: String, directory: FileManager.SearchPathDirectory = .documentDirectory) {
        guard let baseURL = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: sharedContainerId) else {
            return nil
        }
        
-        var finalBaseURL = baseURL
+        var finalBaseURL = baseURL.absoluteURL
        
        switch directory {
        case .documentDirectory:
@@ -47,41 +80,70 @@ open class LocalFileProvider: FileProvider, FileProviderMonitor {
        case .cachesDirectory:
            finalBaseURL = baseURL.appendingPathComponent("Library/Caches")
        case .applicationSupportDirectory:
-            finalBaseURL = baseURL.appendingPathComponent("Library/Application%20support")
+            finalBaseURL = baseURL.appendingPathComponent("Library/Application support")
        default:
            break
        }
        
        self.init(baseURL: finalBaseURL)
+        self.isCoorinating = true
        
        try? fileManager.createDirectory(at: finalBaseURL, withIntermediateDirectories: true)
    }
    
+    /// Initializes provider for the specified local URL.
+    ///
+    /// - Parameter baseURL: Local URL location for base directory.
    public init (baseURL: URL) {
+        guard baseURL.isFileURL else {
+            fatalError("Cannot initialize a Local provider from remote URL.")
+        }
        self.baseURL = baseURL
-        self.isPathRelative = true
        self.currentPath = ""
        self.credential = nil
        self.isCoorinating = false
        
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: DispatchQueue.Attributes.concurrent)
+        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: .concurrent)
        operation_queue = OperationQueue()
        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
        
        fileProviderManagerDelegate = LocalFileProviderManagerDelegate(provider: self)
        opFileManager.delegate = fileProviderManagerDelegate
-        
    }
    
-    @available(*, deprecated, message: "Overriding this method has no effect anymore.")
-    open class func defaultBaseURL() -> URL {
-        return FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
+    public required convenience init?(coder aDecoder: NSCoder) {
+        guard let baseURL = aDecoder.decodeObject(forKey: "baseURL") as? URL else {
+            return nil
+        }
+        self.init(baseURL: baseURL)
+        self.currentPath   = aDecoder.decodeObject(forKey: "currentPath") as? String ?? ""
+        self.isCoorinating = aDecoder.decodeBool(forKey: "isCoorinating")
+    }
+    
+    open func encode(with aCoder: NSCoder) {
+        aCoder.encode(self.baseURL, forKey: "currentPath")
+        aCoder.encode(self.currentPath, forKey: "currentPath")
+        aCoder.encode(self.isCoorinating, forKey: "isCoorinating")
+    }
+    
+    public static var supportsSecureCoding: Bool {
+        return true
+    }
+    
+    public func copy(with zone: NSZone? = nil) -> Any {
+        let copy = LocalFileProvider(baseURL: self.baseURL!)
+        copy.currentPath = self.currentPath
+        copy.undoManager = self.undoManager
+        copy.isCoorinating = self.isCoorinating
+        copy.delegate = self.delegate
+        copy.fileOperationDelegate = self.fileOperationDelegate
+        return copy
    }
    
    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
        dispatch_queue.async {
            do {
-                let contents = try self.fileManager.contentsOfDirectory(at: self.url(of: path), includingPropertiesForKeys: [.nameKey, .fileSizeKey, .fileAllocatedSizeKey, .creationDateKey, .contentModificationDateKey, .isHiddenKey, .volumeIsReadOnlyKey], options: .skipsSubdirectoryDescendants)
+                let contents = try self.fileManager.contentsOfDirectory(at: self.url(of: path), includingPropertiesForKeys: nil, options: .skipsSubdirectoryDescendants)
                let filesAttributes = contents.flatMap({ (fileURL) -> LocalFileObject? in
                    let path = self.relativePathOf(url: fileURL)
                    return LocalFileObject(fileWithPath: path, relativeTo: self.baseURL)
@@ -93,202 +155,181 @@ open class LocalFileProvider: FileProvider, FileProviderMonitor {
        }
    }
    
-    open func storageProperties(completionHandler: (@escaping (_ total: Int64, _ used: Int64) -> Void)) {
-        let dict = (try? FileManager.default.attributesOfFileSystem(forPath: baseURL?.path ?? "/"))
-        let totalSize = (dict?[.systemSize] as? NSNumber)?.int64Value ?? -1;
-        let freeSize = (dict?[.systemFreeSize] as? NSNumber)?.int64Value ?? 0;
-        completionHandler(totalSize, totalSize - freeSize)
-    }
-    
    open func attributesOfItem(path: String, completionHandler: @escaping ((_ attributes: FileObject?, _ error: Error?) -> Void)) {
        dispatch_queue.async {
            completionHandler(LocalFileObject(fileWithPath: path, relativeTo: self.baseURL), nil)
        }
    }
    
+    open func storageProperties(completionHandler: (@escaping (_ total: Int64, _ used: Int64) -> Void)) {
+        let values = try? baseURL?.resourceValues(forKeys: [.volumeTotalCapacityKey, .volumeAvailableCapacityKey])
+        let totalSize = Int64(values??.volumeTotalCapacity ?? -1)
+        let freeSize = Int64(values??.volumeAvailableCapacity ?? 0)
+        completionHandler(totalSize, totalSize - freeSize)
+    }
+    
+    open func searchFiles(path: String, recursive: Bool, query: NSPredicate, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
+        dispatch_queue.async {
+            let iterator = self.fileManager.enumerator(at: self.url(of: path), includingPropertiesForKeys: nil, options: recursive ? [] : [.skipsSubdirectoryDescendants, .skipsPackageDescendants]) { (url, e) -> Bool in
+                completionHandler([], e)
+                return true
+            }
+            var result = [LocalFileObject]()
+            while let fileURL = iterator?.nextObject() as? URL {
+                let path = self.relativePathOf(url: fileURL)
+                if let fileObject = LocalFileObject(fileWithPath: path, relativeTo: self.baseURL), query.evaluate(with: fileObject.mapPredicate()) {
+                    result.append(fileObject)
+                    foundItemHandler?(fileObject)
+                }
+            }
+            completionHandler(result, nil)
+        }
+    }
+    
+    open func isReachable(completionHandler: @escaping (Bool) -> Void) {
+        dispatch_queue.async {
+            completionHandler(self.fileManager.isReadableFile(atPath: self.baseURL!.path))
+        }
+    }
+    
    open weak var fileOperationDelegate : FileOperationDelegate?
    
    @discardableResult
    open func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.create(path: (atPath as NSString).appendingPathComponent(folderName) + "/")
-        let url = self.url(of: atPath).appendingPathComponent(folderName)
-        
-        let operationHandler: (URL) -> Void = { url in
-            do {
-                try self.opFileManager.createDirectory(at: url, withIntermediateDirectories: true, attributes: [:])
-                completionHandler?(nil)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                }
-            } catch let e {
-                completionHandler?(e)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            }
-        }
-        
-        if isCoorinating {
-            let intent = NSFileAccessIntent.writingIntent(with: url, options: .forReplacing)
-            self.coordinated(intents: [intent], completionHandler: operationHandler, errorHandler: { error in
-                completionHandler?(error)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            })
-        } else {
-            operation_queue.addOperation {
-                operationHandler(url)
-            }
-        }
-        
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
-    }
-    
-    @discardableResult
-    open func create(file fileName: String, at atPath: String, contents data: Data?, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.create(path: (atPath as NSString).appendingPathComponent(fileName))
-        let url = self.url(of: atPath).appendingPathComponent(fileName, isDirectory: false)
-        
-        let operationHandler: (URL) -> Void = { url in
-            let success = self.opFileManager.createFile(atPath: url.path, contents: data, attributes: nil)
-            if success {
-                completionHandler?(nil)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                }
-            } else {
-                completionHandler?(self.throwError(atPath, code: URLError.cannotCreateFile as FoundationErrorEnum))
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            }
-        }
-        
-        if isCoorinating {
-            let intent = NSFileAccessIntent.writingIntent(with:url, options: .forReplacing)
-            self.coordinated(intents: [intent], completionHandler: operationHandler, errorHandler: { error in
-                completionHandler?(error)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            })
-        } else {
-            operation_queue.addOperation {
-                operationHandler(url)
-            }
-        }
-        
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
+        return self.doOperation(opType, completionHandler: completionHandler)
    }
    
    @discardableResult
    open func moveItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.move(source: path, destination: toPath)
-        let sourceUrl = self.url(of: path)
-        let destUrl = self.url(of: toPath)
-        
-        let sourceIntent = NSFileAccessIntent.writingIntent(with: sourceUrl, options: .forDeleting)
-        let destIntent = NSFileAccessIntent.writingIntent(with: destUrl, options: .forReplacing)
-        
-        let operationHandler: (URL, URL) -> Void = { sourceUrl, destUrl in
-            if !overwrite && self.fileManager.fileExists(atPath: destUrl.path) {
-                completionHandler?(self.throwError(toPath, code: URLError.cannotMoveFile as FoundationErrorEnum))
-                return
-            }
-            do {
-                try self.opFileManager.moveItem(at: sourceUrl, to: destUrl)
-                completionHandler?(nil)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                }
-            } catch let e {
-                completionHandler?(e)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            }
+
+        if !overwrite && self.fileManager.fileExists(atPath: self.url(of: toPath).path) {
+            completionHandler?(self.throwError(toPath, code: CocoaError.fileWriteFileExists as FoundationErrorEnum))
+            return nil
        }
        
-        if isCoorinating {
-            coordinated(intents: [sourceIntent, destIntent], completionHandler: operationHandler) { (error) in
-                completionHandler?(error)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            }
-        } else {
-            operation_queue.addOperation {
-                operationHandler(sourceUrl, destUrl)
-            }
-        }
-        
-        
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
+        return self.doOperation(opType, completionHandler: completionHandler)
    }
    
    @discardableResult
    open func copyItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.copy(source: path, destination: toPath)
-        let sourceUrl = self.url(of: path)
-        let destUrl = self.url(of: toPath)
        
-        let sourceIntent = NSFileAccessIntent.readingIntent(with: sourceUrl, options: .withoutChanges)
-        let destIntent = NSFileAccessIntent.writingIntent(with: destUrl, options: .forDeleting)
-        
-        let operationHandler: (URL, URL) -> Void = { sourceUrl, destUrl in
-            if !overwrite && self.fileManager.fileExists(atPath: destUrl.path) {
-                completionHandler?(self.throwError(toPath, code: URLError.cannotMoveFile as FoundationErrorEnum))
-                return
-            }
-            do {
-                try self.opFileManager.copyItem(at: sourceUrl, to: destUrl)
-                completionHandler?(nil)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                }
-            } catch let e {
-                completionHandler?(e)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
+        if !overwrite && self.fileManager.fileExists(atPath: self.url(of: toPath).path) {
+            self.dispatch_queue.async {
+                completionHandler?(self.throwError(toPath, code: CocoaError.fileWriteFileExists as FoundationErrorEnum))
            }
+            return nil
        }
        
-        if isCoorinating {
-            coordinated(intents: [sourceIntent, destIntent], moving: true, completionHandler: operationHandler) { (error) in
-                completionHandler?(error)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            }
-        } else {
-            operation_queue.addOperation {
-                operationHandler(sourceUrl, destUrl)
-            }
-        }
-        
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
+        return self.doOperation(opType, completionHandler: completionHandler)
    }
    
    @discardableResult
    open func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.remove(path: path)
-        let url = self.url(of: path)
+        return self.doOperation(opType, completionHandler: completionHandler)
+    }
+    
+    @discardableResult
+    open func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        if !overwrite && self.fileManager.fileExists(atPath: self.url(of: toPath).path) {
+            self.dispatch_queue.async {
+                completionHandler?(self.throwError(toPath, code: CocoaError.fileWriteFileExists as FoundationErrorEnum))
+            }
+            return nil
+        }
+        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
+        return self.doOperation(opType, forUploading: true, completionHandler: completionHandler)
+    }
+    
+    @discardableResult
+    open func copyItem(path: String, toLocalURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let opType = FileOperationType.copy(source: path, destination: toLocalURL.absoluteString)
+        return self.doOperation(opType, completionHandler: completionHandler)
+    }
+    
+    dynamic func doSimpleOperation(_ box: UndoBox) {
+        guard let _ = self.undoManager else { return }
+        _ = self.doOperation(box.undoOperation) { (_) in
+            return
+        }
+    }
+    
+    @discardableResult
+    fileprivate func doOperation(_ opType: FileOperationType, data: Data? = nil, atomically: Bool = false, forUploading: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        
-        let operationHandler: (URL) -> Void = { url in
+        func urlofpath(path: String) -> URL {
+            if path.hasPrefix("file://") {
+                let removedSchemePath = path.replacingOccurrences(of: "file://", with: "", options: .anchored)
+                let pDecodedPath = removedSchemePath.removingPercentEncoding ?? removedSchemePath
+                return URL(fileURLWithPath: pDecodedPath)
+            } else {
+                return self.url(of: path)
+            }
+        }
+        
+        guard let sourcePath = opType.source else { return nil }
+        let destPath = opType.destination
+        let source: URL = urlofpath(path: sourcePath)
+        
+        let dest: URL?
+        if let destPath = destPath {
+            dest = urlofpath(path: destPath)
+        } else {
+            dest = nil
+        }
+        
+        if let undoManager = self.undoManager, let undoOp = self.undoOperation(for: opType) {
+            let undoBox = UndoBox(provider: self, operation: opType, undoOperation: undoOp)
+            undoManager.beginUndoGrouping()
+            undoManager.registerUndo(withTarget: self, selector: #selector(LocalFileProvider.doSimpleOperation(_:)), object: undoBox)
+            undoManager.setActionName(opType.actionDescription)
+            undoManager.endUndoGrouping()
+        }
+        
+        var successfulSecurityScopedResourceAccess = false
+        
+        let operationHandler: (URL, URL?) -> Void = { source, dest in
            do {
-                let successfulSecurityScopedResourceAccess = url.startAccessingSecurityScopedResource()
-                try self.opFileManager.removeItem(at: url)
-                if successfulSecurityScopedResourceAccess {
-                    url.stopAccessingSecurityScopedResource()
+                switch opType {
+                case .create:
+                    if sourcePath.hasSuffix("/") {
+                        try self.opFileManager.createDirectory(at: source, withIntermediateDirectories: true, attributes: [:])
+                    } else {
+                        try data?.write(to: source, options: .atomic)
+                    }
+                case .modify:
+                    try data?.write(to: source, options: atomically ? [.atomic] : [])
+                case .copy:
+                    guard let dest = dest else { return }
+                    try self.opFileManager.copyItem(at: source, to: dest)
+                case .move:
+                    guard let dest = dest else { return }
+                    try self.opFileManager.moveItem(at: source, to: dest)
+                case.remove:
+                    try self.opFileManager.removeItem(at: source)
+                default:
+                    return
+                }
+                if successfulSecurityScopedResourceAccess {
+                    source.stopAccessingSecurityScopedResource()
+                }
+                
+                self.dispatch_queue.async {
+                    completionHandler?(nil)
                }
-                completionHandler?(nil)
                DispatchQueue.main.async {
                    self.delegate?.fileproviderSucceed(self, operation: opType)
                }
            } catch let e {
-                completionHandler?(e)
+                if successfulSecurityScopedResourceAccess {
+                    source.stopAccessingSecurityScopedResource()
+                }
+                self.dispatch_queue.async {
+                    completionHandler?(e)
+                }
                DispatchQueue.main.async {
                    self.delegate?.fileproviderFailed(self, operation: opType)
                }
@@ -296,77 +337,65 @@ open class LocalFileProvider: FileProvider, FileProviderMonitor {
        }
        
        if isCoorinating {
-            let intent = NSFileAccessIntent.writingIntent(with:url, options: .forReplacing)
-            self.coordinated(intents: [intent], completionHandler: operationHandler, errorHandler: { error in
-                completionHandler?(error)
+            successfulSecurityScopedResourceAccess = source.startAccessingSecurityScopedResource()
+            var intents = [NSFileAccessIntent]()
+            switch opType {
+            case .create, .modify:
+                intents.append(NSFileAccessIntent.writingIntent(with: source, options: .forReplacing))
+            case .copy:
+                guard let dest = dest else { return nil }
+                intents.append(NSFileAccessIntent.readingIntent(with: source, options: forUploading ? .forUploading : .withoutChanges))
+                intents.append(NSFileAccessIntent.writingIntent(with: dest, options: .forReplacing))
+            case .move:
+                guard let dest = dest else { return nil }
+                intents.append(NSFileAccessIntent.writingIntent(with: source, options: .forMoving))
+                intents.append(NSFileAccessIntent.writingIntent(with: dest, options: .forReplacing))
+            case .remove:
+                intents.append(NSFileAccessIntent.writingIntent(with: source, options: .forDeleting))
+            default:
+                return nil
+            }
+            self.coordinated(intents: intents, completionHandler: operationHandler, errorHandler: { error in
+                self.dispatch_queue.async {
+                    completionHandler?(error)
+                }
                DispatchQueue.main.async {
                    self.delegate?.fileproviderFailed(self, operation: opType)
                }
            })
        } else {
            operation_queue.addOperation {
-                operationHandler(url)
+                operationHandler(source, dest)
            }
        }
        
        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
    }
    
-    @discardableResult
-    open func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        // TODO: Make use of overwrite parameter
-        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
-        operation_queue.addOperation {
-            do {
-                try self.opFileManager.copyItem(at: localFile, to: self.url(of: toPath))
-                completionHandler?(nil)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                }
-            } catch let e {
-                completionHandler?(e)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            }
-        }
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
-    }
-    
-    @discardableResult
-    open func copyItem(path: String, toLocalURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.copy(source: path, destination: toLocalURL.absoluteString)
-        operation_queue.addOperation {
-            do {
-                try self.opFileManager.copyItem(at: self.url(of: path), to: toLocalURL)
-                completionHandler?(nil)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                }
-            } catch let e {
-                completionHandler?(e)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            }
-        }
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
-    }
-    
    @discardableResult
    open func contents(path: String, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
        let opType = FileOperationType.fetch(path: path)
        let url = self.url(of: path)
        
        let operationHandler: (URL) -> Void = { url in
-            let data = self.fileManager.contents(atPath: url.path)
-            completionHandler(data, nil)
+            do {
+                let data = try Data(contentsOf: url)
+                self.dispatch_queue.async {
+                    completionHandler(data, nil)
+                }
+            } catch let e {
+                self.dispatch_queue.async {
+                    completionHandler(nil, e)
+                }
+            }
        }
        
        if isCoorinating {
            let intent = NSFileAccessIntent.readingIntent(with: url, options: .withoutChanges)
            coordinated(intents: [intent], completionHandler: operationHandler, errorHandler: { error in
-                completionHandler(nil, error)
+                self.dispatch_queue.async {
+                    completionHandler(nil, error)
+                }
                DispatchQueue.main.async {
                    self.delegate?.fileproviderFailed(self, operation: opType)
                }
@@ -382,7 +411,14 @@ open class LocalFileProvider: FileProvider, FileProviderMonitor {
    
    @discardableResult
    open func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
-        if length < 0 {
+        if length == 0 || offset < 0 {
+            dispatch_queue.async {
+                completionHandler(Data(), nil)
+            }
+            return nil
+        }
+        
+        if offset == 0 && length < 0 {
            return self.contents(path: path, completionHandler: completionHandler)
        }
        
@@ -390,20 +426,37 @@ open class LocalFileProvider: FileProvider, FileProviderMonitor {
        let url = self.url(of: path)
        
        let operationHandler: (URL) -> Void = { url in
-            guard self.fileManager.fileExists(atPath: url.path) && !url.fileIsDirectory else {
-                completionHandler(nil, self.throwError(path, code: URLError.cannotOpenFile as FoundationErrorEnum))
-                return
-            }
            guard let handle = FileHandle(forReadingAtPath: url.path) else {
-                completionHandler(nil, self.throwError(path, code: URLError.cannotOpenFile as FoundationErrorEnum))
+                self.dispatch_queue.async {
+                    completionHandler(nil, self.throwError(path, code: CocoaError.fileNoSuchFile as FoundationErrorEnum))
+                }
                return
            }
+            
            defer {
                handle.closeFile()
            }
+            
+            let size = LocalFileObject(fileWithURL: url)?.size ?? -1
+            guard size > offset else {
+                self.dispatch_queue.async {
+                    completionHandler(nil, self.throwError(path, code: CocoaError.fileReadTooLarge as FoundationErrorEnum))
+                }
+                return
+            }
            handle.seek(toFileOffset: UInt64(offset))
+            guard Int64(handle.offsetInFile) == offset else {
+                self.dispatch_queue.async {
+                    completionHandler(nil, self.throwError(path, code: CocoaError.fileReadTooLarge as FoundationErrorEnum))
+                }
+                return
+            }
+            
            let data = handle.readData(ofLength: length)
-            completionHandler(data, nil)
+            
+            self.dispatch_queue.async {
+                completionHandler(data, nil)
+            }
        }
        
        if isCoorinating {
@@ -424,67 +477,10 @@ open class LocalFileProvider: FileProvider, FileProviderMonitor {
    }
    
    @discardableResult
-    open func writeContents(path: String, contents data: Data, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.modify(path: path)
-        let url = self.url(of: path)
-        var options: Data.WritingOptions = []
-        if atomically {
-            options.insert(.atomic)
-        }
-        if overwrite {
-            options.insert(.withoutOverwriting)
-        }
-        
-        let operationHandler: (URL) -> Void = { url in
-            do {
-                try data.write(to: url, options: atomically ? [.atomic] : [])
-                completionHandler?(nil)
-                DispatchQueue.main.async{
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                }
-            } catch let e {
-                completionHandler?(e)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            }
-        }
-        
-        if isCoorinating {
-            let intent = NSFileAccessIntent.writingIntent(with: url, options: .forReplacing)
-            coordinated(intents: [intent], completionHandler: operationHandler, errorHandler: { error in
-                completionHandler?(error)
-                DispatchQueue.main.async {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                }
-            })
-        } else {
-            operation_queue.addOperation {
-                operationHandler(url)
-            }
-        }
-        
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
-    }
-    
-    open func searchFiles(path: String, recursive: Bool, query: String, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
-        dispatch_queue.async { 
-            let iterator = self.fileManager.enumerator(at: self.url(of: path), includingPropertiesForKeys: nil, options: recursive ? [] : [.skipsSubdirectoryDescendants, .skipsPackageDescendants]) { (url, e) -> Bool in
-                completionHandler([], e)
-                return true
-            }
-            var result = [LocalFileObject]()
-            while let fileURL = iterator?.nextObject() as? URL {
-                if fileURL.lastPathComponent.lowercased().contains(query.lowercased()) {
-                    let path = self.relativePathOf(url: fileURL)
-                    if let fileObject = LocalFileObject(fileWithPath: path, relativeTo: self.baseURL) {
-                        result.append(fileObject)
-                        foundItemHandler?(fileObject)
-                    }
-                }
-            }
-            completionHandler(result, nil)
-        }
+    open func writeContents(path: String, contents data: Data?, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let fileExists = fileManager.fileExists(atPath: url(of: path).path)
+        let opType: FileOperationType = fileExists ? .modify(path: path) : .create(path: path)
+        return self.doOperation(opType, data: data ?? Data(), atomically: atomically, completionHandler: completionHandler)
    }
    
    fileprivate var monitors = [LocalFolderMonitor]()
@@ -492,7 +488,7 @@ open class LocalFileProvider: FileProvider, FileProviderMonitor {
    open func registerNotifcation(path: String, eventHandler: @escaping (() -> Void)) {
        self.unregisterNotifcation(path: path)
        let dirurl = self.url(of: path)
-        let isdir = (try? dirurl.resourceValues(forKeys: [.isDirectoryKey]).isDirectory ?? false) ?? false
+        let isdir = (try? dirurl.resourceValues(forKeys: [.isDirectoryKey]))?.isDirectory ?? false
        if !isdir {
            return
        }
@@ -515,20 +511,22 @@ open class LocalFileProvider: FileProvider, FileProviderMonitor {
    }
    
    open func isRegisteredForNotification(path: String) -> Bool {
-        return monitors.map( { self.relativePathOf(url: $0.url) } ).contains(path)
-    }
-    
-    open func copy(with zone: NSZone? = nil) -> Any {
-        let copy = LocalFileProvider(baseURL: self.baseURL!)
-        copy.currentPath = self.currentPath
-        copy.delegate = self.delegate
-        copy.fileOperationDelegate = self.fileOperationDelegate
-        copy.isPathRelative = self.isPathRelative
-        return copy
+        return monitors.map( { self.relativePathOf(url: $0.url) } ).contains(path.trimmingCharacters(in: CharacterSet(charactersIn: "/")))
    }
 }

 public extension LocalFileProvider {
+    /**
+     Creates a symbolic link at the specified path that points to an item at the given path.
+     This method does not traverse symbolic links contained in destination path, making it possible
+     to create symbolic links to locations that do not yet exist.
+     Also, if the final path component is a symbolic link, that link is not followed.
+    
+     - Parameters:
+       - symbolicLink: The file path at which to create the new symbolic link. The last component of the path issued as the name of the link.
+       - withDestinationPath: The path that contains the item to be pointed to by the link. In other words, this is the destination of the link.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+    */
    public func create(symbolicLink path: String, withDestinationPath destPath: String, completionHandler: SimpleCompletionHandler) {
        operation_queue.addOperation {
            do {
@@ -546,6 +544,11 @@ public extension LocalFileProvider {
        }
    }
    
+    /// Returns the path of the item pointed to by a symbolic link.
+    ///
+    /// - Parameters:
+    ///   - path: The path of a file or directory.
+    ///   - completionHandler: Returns destination url of given symbolic link, or an `Error` object if it fails.
    public func destination(ofSymbolicLink path: String, completionHandler: @escaping (_ url: URL?, _ error: Error?) -> Void) {
        dispatch_queue.async {
            do {
@@ -567,23 +570,25 @@ internal extension LocalFileProvider {
                errorHandler?(error)
                return
            }
-            completionHandler(intents[0].url)
+            completionHandler(intents.first!.url)
        }
    }
    
-    func coordinated(intents: [NSFileAccessIntent], moving: Bool = false, completionHandler: @escaping (_ sourceUrl: URL, _ destURL: URL) -> Void, errorHandler:  ((_ error: Error) -> Void)? = nil) {
+    func coordinated(intents: [NSFileAccessIntent], moving: Bool = false, completionHandler: @escaping (_ sourceUrl: URL, _ destURL: URL?) -> Void, errorHandler:  ((_ error: Error) -> Void)? = nil) {
        let coordinator = NSFileCoordinator(filePresenter: nil)
        coordinator.coordinate(with: intents, queue: operation_queue) { (error) in
            if let error = error {
                errorHandler?(error)
                return
            }
-            if moving {
-                coordinator.item(at: intents[0].url, willMoveTo: intents[1].url)
+            guard let newSource: URL = intents.first?.url else { return }
+            let newDest: URL? = intents.dropFirst().first?.url
+            if moving, let newDest = newDest {
+                coordinator.item(at: newSource, willMoveTo: newDest)
            }
-            completionHandler(intents[0].url, intents[1].url)
-            if moving {
-                coordinator.item(at: intents[0].url, didMoveTo: intents[1].url)
+            completionHandler(newSource, newDest)
+            if moving, let newDest = newDest {
+                coordinator.item(at: newSource, didMoveTo: newDest)
            }
        }
    }
@@ -8,26 +8,25 @@

 import Foundation

+/// Containts path, url and attributes of a local file or resource.
 public final class LocalFileObject: FileObject {
    internal override init(url: URL, name: String, path: String) {
        super.init(url: url, name: name, path: path)
    }
    
+    /// Initiates a `LocalFileObject` with attributes of file in path.
    public convenience init? (fileWithPath path: String, relativeTo relativeURL: URL?) {
        var fileURL: URL?
-        var rpath = path.replacingOccurrences(of: relativeURL?.absoluteString  ?? "", with: "", options: .anchored)
-        if path.hasPrefix("/") {
+        var rpath = path.replacingOccurrences(of: relativeURL?.path ?? "", with: "", options: .anchored)
+        if relativeURL != nil && rpath.hasPrefix("/") {
            rpath.remove(at: rpath.startIndex)
        }
-        if rpath.isEmpty {
-            fileURL = relativeURL
+        if #available(iOS 9.0, macOS 10.11, tvOS 9.0, *) {
+            fileURL = URL(fileURLWithPath: rpath, relativeTo: relativeURL)
        } else {
-            if #available(iOS 9.0, macOS 10.11, tvOS 9.0, *) {
-                fileURL = URL(fileURLWithPath: rpath, relativeTo: relativeURL)
-            } else {
-                fileURL = URL(string: rpath, relativeTo: relativeURL)
-            }
+            fileURL = URL(string: rpath.isEmpty ? "./" : rpath, relativeTo: relativeURL)
        }
+        
        if let fileURL = fileURL {
            self.init(fileWithURL: fileURL)
        } else {
@@ -35,39 +34,54 @@ public final class LocalFileObject: FileObject {
        }
    }
    
+    /// Initiates a `LocalFileObject` with attributes of file in url.
    public convenience init?(fileWithURL fileURL: URL) {
        do {
-            let values = try fileURL.resourceValues(forKeys: [.nameKey, .fileSizeKey, .fileAllocatedSizeKey, .creationDateKey, .contentModificationDateKey, .fileResourceTypeKey, .isHiddenKey, .isWritableKey, .typeIdentifierKey, .generationIdentifierKey])
+            let values = try fileURL.resourceValues(forKeys: [.nameKey, .fileSizeKey, .totalFileSizeKey, .fileAllocatedSizeKey, .totalFileAllocatedSizeKey, .creationDateKey, .contentModificationDateKey, .fileResourceTypeKey, .isHiddenKey, .isWritableKey, .typeIdentifierKey, .generationIdentifierKey, .documentIdentifierKey])
            let path = fileURL.relativePath.hasPrefix("/") ? fileURL.relativePath : "/" + fileURL.relativePath
            
            self.init(url: fileURL, name: values.name ?? fileURL.lastPathComponent, path: path)
            for (key, value) in values.allValues {
-                self.allValues[key.rawValue] = value
+                self.allValues[key] = value
            }
        } catch {
            return nil
        }
    }
    
+    /// The total size allocated on disk for the file
    open internal(set) var allocatedSize: Int64 {
        get {
-            return allValues[URLResourceKey.fileAllocatedSizeKey.rawValue] as? Int64 ?? 0
+            return allValues[.fileAllocatedSizeKey] as? Int64 ?? 0
        }
        set {
-            allValues[URLResourceKey.fileAllocatedSizeKey.rawValue] = Int(exactly: newValue) ?? Int.max
+            allValues[.fileAllocatedSizeKey] = Int(exactly: newValue) ?? Int.max
        }
    }
    
+    /// The document identifier is a value assigned by the kernel/system to a file or directory. 
+    /// This value is used to identify the document regardless of where it is moved on a volume. 
+    /// The identifier persists across system restarts.
+    open internal(set) var id: Int? {
+        get {
+            return allValues[.documentIdentifierKey] as? Int
+        }
+        set {
+            allValues[.documentIdentifierKey] = newValue
+        }
+    }
+    
+    /// The revision of file, which changes when a file contents are modified. 
+    /// Changes to attributes or other file metadata do not change the identifier.
    open var rev: String? {
        get {
-            let data = allValues[URLResourceKey.generationIdentifierKey.rawValue] as? Data
+            let data = allValues[.generationIdentifierKey] as? Data
            return data?.map { String(format: "%02hhx", $0) }.joined()
        }
    }
-
 }

-internal class LocalFolderMonitor {
+internal final class LocalFolderMonitor {
    fileprivate let source: DispatchSourceFileSystemObject
    fileprivate let descriptor: CInt
    fileprivate let qq: DispatchQueue = DispatchQueue.global(qos: .default)
@@ -79,18 +93,21 @@ internal class LocalFolderMonitor {
    init(url: URL, handler: @escaping ()->Void) {
        self.url = url
        descriptor = open((url as NSURL).fileSystemRepresentation, O_EVTONLY)
-        source = DispatchSource.makeFileSystemObjectSource(fileDescriptor: descriptor, eventMask: DispatchSource.FileSystemEvent.write, queue: qq)
+        source = DispatchSource.makeFileSystemObjectSource(fileDescriptor: descriptor, eventMask: .write, queue: qq)
        // Folder monitoring is recursive and deep. Monitoring a root folder may be very costly
        // We have a 0.2 second delay to ensure we wont call handler 1000s times when there is
        // a huge file operation. This ensures app will work smoothly while this 250 milisec won't
        // affect user experince much
-        let main_handler: ()->Void = {
+        let main_handler: ()->Void = { [weak self] in
+            guard let `self` = self else { return }
            if Date().timeIntervalSinceReferenceDate < self.monitoredTime + 0.2 {
                return
            }
            self.monitoredTime = Date().timeIntervalSinceReferenceDate
-            DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.25, execute: {
+            self.source.suspend()
+            DispatchQueue.main.asyncAfter(deadline: .now() + 0.25, execute: {
                handler()
+                self.source.resume()
            })
        }
        source.setEventHandler(handler: main_handler)
@@ -199,8 +216,11 @@ internal class LocalFileProviderManagerDelegate: NSObject, FileManagerDelegate {
    }
 }

+/// - Note: Local operation handling is limited. Please don't use as much as possible.
 open class LocalOperationHandle: OperationHandle {
+    /// Url of file which operation is doing on
    public let baseURL: URL
+    /// Type of operation
    public let operationType: FileOperationType
    
    init (operationType: FileOperationType, baseURL: URL?) {
@@ -278,18 +298,15 @@ open class LocalOperationHandle: OperationHandle {
        let fp = FileManager()
        let filesList = fp.enumerator(at: pathURL, includingPropertiesForKeys: keys, options: enumOpt, errorHandler: nil)
        while let fileURL = filesList?.nextObject() as? URL {
-            do {
-                let values = try fileURL.resourceValues(forKeys: [.isDirectoryKey, .fileSizeKey])
-                let isdir = values.isDirectory ?? false
-                let size = Int64(values.fileSize ?? 0)
-                if isdir {
-                    folders += 1
-                } else {
-                    files += 1
-                }
-                totalsize += size
-            } catch _ {
+            guard let values = try? fileURL.resourceValues(forKeys: [.isDirectoryKey, .fileSizeKey]) else { continue }
+            let isdir = values.isDirectory ?? false
+            let size = Int64(values.fileSize ?? 0)
+            if isdir {
+                folders += 1
+            } else {
+                files += 1
            }
+            totalsize += size
        }
        
        return (folders, files, totalsize)
@@ -297,16 +314,14 @@ open class LocalOperationHandle: OperationHandle {
    }
 }

-internal extension URL {
-    var fileIsDirectory: Bool {
-        return (try? self.resourceValues(forKeys: [.isDirectoryKey]))?.isDirectory ?? false
-    }
+class UndoBox: NSObject {
+    weak var provider: FileProvideUndoable?
+    let operation: FileOperationType
+    let undoOperation: FileOperationType
    
-    var fileSize: Int64 {
-        return Int64((try? self.resourceValues(forKeys: [.fileSizeKey]))?.fileSize ?? -1)
-    }
-    
-    var fileExists: Bool {
-        return self.isFileURL && FileManager.default.fileExists(atPath: self.path)
+    init(provider: FileProvideUndoable, operation: FileOperationType, undoOperation: FileOperationType) {
+        self.provider = provider
+        self.operation = operation
+        self.undoOperation = undoOperation
    }
 }
@@ -1,360 +0,0 @@
-
-//
-//  OneDriveFileProvider.swift
-//  FileProvider
-//
-//  Created by Amir Abbas Mousavian.
-//  Copyright © 2017 Mousavian. Distributed under MIT license.
-//
-
-import Foundation
-import CoreGraphics
-
-// Because this class uses NSURLSession, it's necessary to disable App Transport Security
-// in case of using this class with unencrypted HTTP connection.
-
-open class OneDriveFileProvider: FileProviderBasicRemote {
-    open static let type: String = "OneDrive"
-    open let isPathRelative: Bool
-    open let baseURL: URL?
-    open var serverURL: URL { return baseURL! }
-    open var drive: String
-    open var driveURL: URL {
-        return URL(string: "/drive/\(drive):/", relativeTo: baseURL)!
-    }
-    open var currentPath: String
-    
-    open var dispatch_queue: DispatchQueue
-    open var operation_queue: OperationQueue {
-        willSet {
-            assert(_session == nil, "It's not effective to change dispatch_queue property after session is initialized.")
-        }
-    }
-    
-    open weak var delegate: FileProviderDelegate?
-    open let credential: URLCredential?
-    open private(set) var cache: URLCache?
-    public var useCache: Bool
-    public var validatingCache: Bool
-   
-    fileprivate var _session: URLSession?
-    fileprivate var sessionDelegate: SessionDelegate?
-    public var session: URLSession {
-        if _session == nil {
-            self.sessionDelegate = SessionDelegate(fileProvider: self, credential: credential)
-            let queue = OperationQueue()
-            //queue.underlyingQueue = dispatch_queue
-            let config = URLSessionConfiguration.default
-            config.urlCache = cache
-            config.requestCachePolicy = .returnCacheDataElseLoad
-            _session = URLSession(configuration: config, delegate: sessionDelegate as URLSessionDelegate?, delegateQueue: queue)
-        }
-        return _session!
-    }
-    
-    public init? (credential: URLCredential?, serverURL: URL? = nil, drive: String = "root", cache: URLCache? = nil) {
-        self.baseURL = (serverURL ?? URL(string: "https://api.onedrive.com/")!).appendingPathComponent("")
-        self.drive = drive
-        self.isPathRelative = true
-        self.currentPath = ""
-        self.useCache = false
-        self.validatingCache = true
-        self.cache = cache
-        self.credential = credential
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: DispatchQueue.Attributes.concurrent)
-        operation_queue = OperationQueue()
-        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
-    }
-    
-    deinit {
-        _session?.invalidateAndCancel()
-    }
-    
-    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
-        list(path) { (contents, cursor, error) in
-            completionHandler(contents, error)
-        }
-    }
-    
-    open func attributesOfItem(path: String, completionHandler: @escaping ((_ attributes: FileObject?, _ error: Error?) -> Void)) {
-        let url = URL(string: escaped(path: path), relativeTo: driveURL)!
-        var request = URLRequest(url: url)
-        request.httpMethod = "GET"
-        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderOneDriveError?
-            var fileObject: OneDriveFileObject?
-            if let response = response as? HTTPURLResponse {
-                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
-                dbError = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
-                if let data = data, let jsonStr = String(data: data, encoding: .utf8), let json = jsonToDictionary(jsonStr), let file = OneDriveFileObject(baseURL: self.baseURL, drive: self.drive, json: json) {
-                    fileObject = file
-                }
-            }
-            completionHandler(fileObject, dbError ?? error)
-        }) 
-        task.resume()
-    }
-    
-    open func storageProperties(completionHandler: @escaping ((_ total: Int64, _ used: Int64) -> Void)) {
-        let url = URL(string: "/drive/root", relativeTo: baseURL)!
-        var request = URLRequest(url: url)
-        request.httpMethod = "GET"
-        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var totalSize: Int64 = -1
-            var usedSize: Int64 = 0
-            if let data = data, let jsonStr = String(data: data, encoding: .utf8), let json = jsonToDictionary(jsonStr) {
-                totalSize = (json["total"] as? NSNumber)?.int64Value ?? -1
-                usedSize = (json["used"] as? NSNumber)?.int64Value ?? 0
-            }
-            completionHandler(totalSize, usedSize)
-        }) 
-        task.resume()
-    }
-    
-    open weak var fileOperationDelegate: FileOperationDelegate?
-}
-
-extension OneDriveFileProvider: FileProviderOperations {
-    
-    
-    public func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let path = (atPath as NSString).appendingPathComponent(folderName) + "/"
-        return doOperation(.create(path: path), completionHandler: completionHandler)
-    }
-    
-    public func create(file fileName: String, at path: String, contents data: Data?, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let filePath = (path as NSString).appendingPathComponent(fileName)
-        return self.writeContents(path: filePath, contents: data ?? Data(), completionHandler: completionHandler)
-    }
-    
-    public func moveItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        return doOperation(.move(source: path, destination: toPath), completionHandler: completionHandler)
-    }
-    
-    public func copyItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        return doOperation(.copy(source: path, destination: toPath), completionHandler: completionHandler)
-    }
-    
-    public func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        return doOperation(.remove(path: path), completionHandler: completionHandler)
-    }
-    
-    fileprivate func doOperation(_ operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: operation) ?? true == true else {
-            return nil
-        }
-        guard let sourcePath = operation.source else { return nil }
-        let destPath = operation.destination
-        var request = URLRequest(url: URL(string: sourcePath, relativeTo: driveURL)!)
-        switch operation {
-        case .create:
-            request.httpMethod = "CREATE"
-        case .copy:
-            request.httpMethod = "POST"
-        case .move:
-            request.httpMethod = "PATCH"
-        case .remove:
-            request.httpMethod = "DELETE"
-        default: // modify, link, fetch
-            return nil
-        }
-        
-        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        var requestDictionary = [String: AnyObject]()
-        if let dest = correctPath(destPath) as NSString? {
-            request.setValue("application/json", forHTTPHeaderField: "Content-Type")
-            requestDictionary["parentReference"] = ("/drive/\(drive):" + dest.deletingLastPathComponent) as NSString
-            requestDictionary["name"] = dest.lastPathComponent as NSString
-            request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
-        }
-        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderOneDriveError?
-            if let response = response as? HTTPURLResponse, response.statusCode >= 300, let code = FileProviderHTTPErrorCode(rawValue: response.statusCode) {
-                 dbError = FileProviderOneDriveError(code: code, path: sourcePath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
-            }
-            completionHandler?(dbError ?? error)
-            self.delegateNotify(operation, error: dbError ?? error)
-        })
-        task.taskDescription = operation.json
-        task.resume()
-        return RemoteOperationHandle(operationType: operation, tasks: [task])
-    }
-    
-    public func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
-        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
-            return nil
-        }
-        return upload_simple(toPath, localFile: localFile, overwrite: overwrite, operation: opType, completionHandler: completionHandler)
-    }
-    
-    public func copyItem(path: String, toLocalURL destURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.copy(source: path, destination: destURL.absoluteString)
-        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
-            return nil
-        }
-        let url = URL(string: escaped(path: path) + ":/content", relativeTo: driveURL)!
-        var request = URLRequest(url: url)
-        request.httpMethod = "GET"
-        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        let task = session.downloadTask(with: request, completionHandler: { (cacheURL, response, error) in
-            guard let cacheURL = cacheURL, let httpResponse = response as? HTTPURLResponse , httpResponse.statusCode < 300 else {
-                let code = FileProviderHTTPErrorCode(rawValue: (response as? HTTPURLResponse)?.statusCode ?? -1)
-                let errorData : Data? = nil //Data(contentsOf:cacheURL) // TODO: Figure out how to get error response data for the error description
-                let dbError : FileProviderOneDriveError? = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: errorData ?? Data(), encoding: .utf8)) : nil
-                completionHandler?(dbError ?? error)
-                return
-            }
-            do {
-                try FileManager.default.moveItem(at: cacheURL, to: destURL)
-                completionHandler?(nil)
-            } catch let e {
-                completionHandler?(e)
-            }
-        })
-        task.taskDescription = opType.json
-        task.resume()
-        return RemoteOperationHandle(operationType: opType, tasks: [task])
-    }
-}
-
-extension OneDriveFileProvider: FileProviderReadWrite {
-    public func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
-        let opType = FileOperationType.fetch(path: path)
-        let url =  URL(string: escaped(path: path) + ":/content", relativeTo: driveURL)!
-        var request = URLRequest(url: url)
-        request.httpMethod = "GET"
-        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        if length > 0 {
-            request.setValue("bytes=\(offset)-\(offset + length - 1)", forHTTPHeaderField: "Range")
-        } else if offset > 0 && length < 0 {
-            request.setValue("bytes=\(offset)-", forHTTPHeaderField: "Range")
-        }
-        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderOneDriveError?
-            if let httpResponse = response as? HTTPURLResponse , httpResponse.statusCode >= 300, let code = FileProviderHTTPErrorCode(rawValue: httpResponse.statusCode) {
-                dbError = FileProviderOneDriveError(code: code, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8))
-            }
-            let filedata = dbError ?? error == nil ? data : nil
-            completionHandler(filedata, dbError ?? error)
-        })
-        task.taskDescription = opType.json
-        task.resume()
-        return RemoteOperationHandle(operationType: opType, tasks: [task])
-    }
-    
-    public func writeContents(path: String, contents data: Data, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.modify(path: path)
-        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
-            return nil
-        }
-        // FIXME: remove 150MB restriction
-        return upload_simple(path, data: data, overwrite: overwrite, operation: opType, completionHandler: completionHandler)
-    }
-    
-    public func searchFiles(path: String, recursive: Bool, query: String, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
-        var foundFiles = [OneDriveFileObject]()
-        search(path, query: query, foundItem: { (file) in
-            foundFiles.append(file)
-            foundItemHandler?(file)
-            }, completionHandler: { (error) in
-                completionHandler(foundFiles, error)
-        })
-    }
-    
-    fileprivate func registerNotifcation(path: String, eventHandler: (() -> Void)) {
-        /* There is two ways to monitor folders changing in OneDrive. Either using webooks
-         * which means you have to implement a server to translate it to push notifications
-         * or using apiv2 list_folder/longpoll method. The second one is implemeted here.
-         * Tough webhooks are much more efficient, longpoll is much simpler to implement!
-         * You can implemnt your own webhook service and replace this method accordingly.
-         */
-        NotImplemented()
-    }
-    fileprivate func unregisterNotifcation(path: String) {
-        NotImplemented()
-    }
-    
-    // TODO: Implement /copy_reference, /get_account & /get_current_account
-}
-
-
-extension OneDriveFileProvider: ExtendedFileProvider {
-    public func thumbnailOfFileSupported(path: String) -> Bool {
-        return true
-    }
-    
-    public func propertiesOfFileSupported(path: String) -> Bool {
-        let fileExt = (path as NSString).pathExtension.lowercased()
-        switch fileExt {
-        case "jpg", "jpeg", "bmp", "gif", "png", "tif", "tiff":
-            return true
-        case "mp3", "aac", "m4a", "wma":
-            return true
-        case "mp4", "mpg", "3gp", "mov", "avi", "wmv":
-            return true
-        default:
-            return false
-        }
-    }
-    
-    public func thumbnailOfFile(path: String, dimension: CGSize?, completionHandler: @escaping ((_ image: ImageClass?, _ error: Error?) -> Void)) {
-        let url: URL
-        if let dimension = dimension {
-            url = URL(string: escaped(path: path) + ":/thumbnails/0/=c\(dimension.width)x\(dimension.height)/content", relativeTo: driveURL)!
-        } else {
-            url = URL(string: escaped(path: path) + ":/thumbnails/0/small/content", relativeTo: driveURL)!
-        }
-        
-        var request = URLRequest(url: url)
-        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        let task = self.session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var image: ImageClass? = nil
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                let responseError = FileProviderOneDriveError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8))
-                completionHandler(nil, responseError)
-                return
-            }
-            if let data = data {
-                image = ImageClass(data: data)
-            }
-            completionHandler(image, error)
-        })
-        task.resume()
-    }
-    
-    public func propertiesOfFile(path: String, completionHandler: @escaping ((_ propertiesDictionary: [String : Any], _ keys: [String], _ error: Error?) -> Void)) {
-        let url = URL(string: escaped(path: path), relativeTo: driveURL)!
-        var request = URLRequest(url: url)
-        request.httpMethod = "GET"
-        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderOneDriveError?
-            var dic = [String: Any]()
-            var keys = [String]()
-            if let response = response as? HTTPURLResponse {
-                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
-                dbError = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
-                if let data = data, let jsonStr = String(data: data, encoding: .utf8), let json = jsonToDictionary(jsonStr) {
-                    (dic, keys) = self.mapMediaInfo(json)
-                }
-            }
-            completionHandler(dic, keys, dbError ?? error)
-        })
-        task.resume()
-    }
-}
-
-extension OneDriveFileProvider: FileProvider {
-    open func copy(with zone: NSZone? = nil) -> Any {
-        let copy = OneDriveFileProvider(credential: self.credential, serverURL: self.baseURL, drive: self.drive, cache: self.cache)!
-        copy.currentPath = self.currentPath
-        copy.delegate = self.delegate
-        copy.fileOperationDelegate = self.fileOperationDelegate
-        copy.useCache = self.useCache
-        copy.validatingCache = self.validatingCache
-        return copy
-    }
-}
@@ -0,0 +1,514 @@
+
+//
+//  OneDriveFileProvider.swift
+//  FileProvider
+//
+//  Created by Amir Abbas Mousavian.
+//  Copyright © 2017 Mousavian. Distributed under MIT license.
+//
+
+import Foundation
+import CoreGraphics
+
+/**
+ Allows accessing to OneDrive stored files, either hosted on Microsoft servers or business coprporate one.
+ This provider doesn't cache or save files internally, however you can set `useCache` and `cache` properties
+ to use Foundation `NSURLCache` system.
+ 
+ - Note: Uploading files and data are limited to 100MB, for now.
+ */
+open class OneDriveFileProvider: FileProviderBasicRemote {
+    open class var type: String { return "OneDrive" }
+    open let baseURL: URL?
+    /// Drive name for user, default is `root`. Changing its value will effect on new operations.
+    open var drive: String
+    /// Generated storage url from server url and drive name
+    open var currentPath: String
+    
+    open var dispatch_queue: DispatchQueue
+    open var operation_queue: OperationQueue {
+        willSet {
+            assert(_session == nil, "It's not effective to change dispatch_queue property after session is initialized.")
+        }
+    }
+    
+    open weak var delegate: FileProviderDelegate?
+    open var credential: URLCredential? {
+        didSet {
+            sessionDelegate?.credential = self.credential
+        }
+    }
+    open private(set) var cache: URLCache?
+    public var useCache: Bool
+    public var validatingCache: Bool
+   
+    fileprivate var _session: URLSession?
+    fileprivate var sessionDelegate: SessionDelegate?
+    public var session: URLSession {
+        get {
+            if _session == nil {
+                self.sessionDelegate = SessionDelegate(fileProvider: self)
+                let queue = OperationQueue()
+                //queue.underlyingQueue = dispatch_queue
+                let config = URLSessionConfiguration.default
+                config.urlCache = cache
+                config.requestCachePolicy = .returnCacheDataElseLoad
+                _session = URLSession(configuration: config, delegate: sessionDelegate as URLSessionDelegate?, delegateQueue: queue)
+                _session?.sessionDescription = UUID().uuidString
+                initEmptySessionHandler(_session!.sessionDescription!)
+            }
+            return _session!
+        }
+        
+        set {
+            assert(newValue.delegate is SessionDelegate, "session instances should have a SessionDelegate instance as delegate.")
+            _session = newValue
+            if session.sessionDescription?.isEmpty ?? true {
+                _session?.sessionDescription = UUID().uuidString
+            }
+            self.sessionDelegate = newValue.delegate as? SessionDelegate
+            initEmptySessionHandler(_session!.sessionDescription!)
+        }
+    }
+    
+    /**
+     Initializer for Onedrive provider with given client ID and Token.
+     These parameters must be retrieved via [Authentication for the OneDrive API](https://dev.onedrive.com/auth/readme.htm).
+     
+     There are libraries like [p2/OAuth2](https://github.com/p2/OAuth2) or [OAuthSwift](https://github.com/OAuthSwift/OAuthSwift) which can facilate the procedure to retrieve token.
+     The latter is easier to use and prefered. Also you can use [auth0/Lock](https://github.com/auth0/Lock.iOS-OSX) which provides graphical user interface.
+     
+     - Parameters:
+       - credential: a `URLCredential` object with Client ID set as `user` and Token set as `password`.
+       - serverURL: server url, Set it if you are trying to connect OneDrive Business server, otherwise leave it
+         `nil` to connect to OneDrive Personal uses.
+       - drive: drive name for user on server, default value is `root`.
+       - cache: A URLCache to cache downloaded files and contents.
+     */
+    public init(credential: URLCredential?, serverURL: URL? = nil, drive: String = "root", cache: URLCache? = nil) {
+        let baseURL = serverURL?.absoluteURL ?? URL(string: "https://api.onedrive.com/")!
+        self.baseURL = baseURL.path.hasSuffix("/") ? baseURL : baseURL.appendingPathComponent("")
+        self.drive = drive
+        self.currentPath = ""
+        self.useCache = false
+        self.validatingCache = true
+        self.cache = cache
+        self.credential = credential
+        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: .concurrent)
+        operation_queue = OperationQueue()
+        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
+    }
+    
+    public required convenience init?(coder aDecoder: NSCoder) {
+        self.init(credential: aDecoder.decodeObject(forKey: "credential") as? URLCredential,
+                  serverURL: aDecoder.decodeObject(forKey: "baseURL") as? URL,
+                  drive: aDecoder.decodeObject(forKey: "drive") as? String ?? "root")
+        self.currentPath   = aDecoder.decodeObject(forKey: "currentPath") as? String ?? ""
+        self.useCache = aDecoder.decodeBool(forKey: "useCache")
+        self.validatingCache = aDecoder.decodeBool(forKey: "validatingCache")
+    }
+    
+    open func encode(with aCoder: NSCoder) {
+        aCoder.encode(self.credential, forKey: "credential")
+        aCoder.encode(self.baseURL, forKey: "baseURL")
+        aCoder.encode(self.drive, forKey: "drive")
+        aCoder.encode(self.currentPath, forKey: "currentPath")
+        aCoder.encode(self.useCache, forKey: "useCache")
+        aCoder.encode(self.validatingCache, forKey: "validatingCache")
+    }
+    
+    public static var supportsSecureCoding: Bool {
+        return true
+    }
+    
+    open func copy(with zone: NSZone? = nil) -> Any {
+        let copy = OneDriveFileProvider(credential: self.credential, serverURL: self.baseURL, drive: self.drive, cache: self.cache)
+        copy.currentPath = self.currentPath
+        copy.delegate = self.delegate
+        copy.fileOperationDelegate = self.fileOperationDelegate
+        copy.useCache = self.useCache
+        copy.validatingCache = self.validatingCache
+        return copy
+    }
+    
+    deinit {
+        if let sessionuuid = _session?.sessionDescription {
+            removeSessionHandler(for: sessionuuid)
+        }
+        
+        if fileProviderCancelTasksOnInvalidating {
+            _session?.invalidateAndCancel()
+        } else {
+            _session?.finishTasksAndInvalidate()
+        }
+    }
+    
+    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
+        list(path) { (contents, cursor, error) in
+            completionHandler(contents, error)
+        }
+    }
+    
+    open func attributesOfItem(path: String, completionHandler: @escaping ((_ attributes: FileObject?, _ error: Error?) -> Void)) {
+        var request = URLRequest(url: url(of: path))
+        request.httpMethod = "GET"
+        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
+        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
+            var serverError: FileProviderOneDriveError?
+            var fileObject: OneDriveFileObject?
+            if let response = response as? HTTPURLResponse {
+                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
+                serverError = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
+                if let json = data?.deserializeJSON(), let file = OneDriveFileObject(baseURL: self.baseURL, drive: self.drive, json: json) {
+                    fileObject = file
+                }
+            }
+            completionHandler(fileObject, serverError ?? error)
+        }) 
+        task.resume()
+    }
+    
+    open func storageProperties(completionHandler: @escaping ((_ total: Int64, _ used: Int64) -> Void)) {
+        var request = URLRequest(url: url())
+        request.httpMethod = "GET"
+        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
+        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
+            var totalSize: Int64 = -1
+            var usedSize: Int64 = 0
+            if let json = data?.deserializeJSON() {
+                totalSize = (json["total"] as? NSNumber)?.int64Value ?? -1
+                usedSize = (json["used"] as? NSNumber)?.int64Value ?? 0
+            }
+            completionHandler(totalSize, usedSize)
+        }) 
+        task.resume()
+    }
+    
+    open func searchFiles(path: String, recursive: Bool, query: NSPredicate, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
+        var foundFiles = [OneDriveFileObject]()
+        var queryStr: String?
+        queryStr = query.findValue(forKey: "name") as? String ?? query.findAllValues(forKey: nil).flatMap { $0.value as? String }.first
+        guard let finalQueryStr = queryStr else { return }
+        search(path, query: finalQueryStr, foundItem: { (file) in
+            if query.evaluate(with: file.mapPredicate()) {
+                foundFiles.append(file)
+                foundItemHandler?(file)
+            }
+        }, completionHandler: { (error) in
+            completionHandler(foundFiles, error)
+        })
+    }
+    
+    open func url(of path: String? = nil, modifier: String? = nil) -> URL {
+        var rpath: String
+        if let path = path {
+            rpath = path
+        } else {
+            rpath = self.currentPath
+        }
+        
+        if rpath.hasPrefix("/") {
+            rpath.remove(at: rpath.startIndex)
+        }
+        if rpath.isEmpty {
+            if let modifier = modifier {
+                return baseURL!.appendingPathComponent("drive/\(drive)/\(modifier)")
+            }
+            return baseURL!.appendingPathComponent("drive/\(drive)")
+        }
+        let driveURL = baseURL!.appendingPathComponent("drive/\(drive):/")
+        rpath = (rpath.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) ?? rpath)
+        rpath = rpath.trimmingCharacters(in: pathTrimSet)
+        if let modifier = modifier {
+            rpath = rpath + ":/" + modifier
+        }
+        return URL(string: rpath, relativeTo: driveURL) ?? driveURL
+    }
+    
+    open func isReachable(completionHandler: @escaping (Bool) -> Void) {
+        var request = URLRequest(url: url())
+        request.httpMethod = "HEAD"
+        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
+        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
+            let status = (response as? HTTPURLResponse)?.statusCode ?? 400
+            completionHandler(status == 200)
+        })
+        task.resume()
+    }
+    
+    open weak var fileOperationDelegate: FileOperationDelegate?
+}
+
+extension OneDriveFileProvider: FileProviderOperations {
+    
+    
+    open func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let path = (atPath as NSString).appendingPathComponent(folderName) + "/"
+        return doOperation(.create(path: path), completionHandler: completionHandler)
+    }
+    
+    open func moveItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        return doOperation(.move(source: path, destination: toPath), completionHandler: completionHandler)
+    }
+    
+    open func copyItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        return doOperation(.copy(source: path, destination: toPath), completionHandler: completionHandler)
+    }
+    
+    open func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        return doOperation(.remove(path: path), completionHandler: completionHandler)
+    }
+    
+    fileprivate func doOperation(_ operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: operation) ?? true == true else {
+            return nil
+        }
+        guard let sourcePath = operation.source else { return nil }
+        let destPath = operation.destination
+        var request = URLRequest(url: url(of: sourcePath))
+        switch operation {
+        case .create:
+            request.httpMethod = "CREATE"
+        case .copy:
+            request.httpMethod = "POST"
+        case .move:
+            request.httpMethod = "PATCH"
+        case .remove:
+            request.httpMethod = "DELETE"
+        default: // modify, link, fetch
+            return nil
+        }
+        
+        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
+        var requestDictionary = [String: AnyObject]()
+        if let dest = correctPath(destPath) as NSString? {
+            request.setValue("application/json", forHTTPHeaderField: "Content-Type")
+            requestDictionary["parentReference"] = ("/drive/\(drive):" + dest.deletingLastPathComponent) as NSString
+            requestDictionary["name"] = dest.lastPathComponent as NSString
+            request.httpBody = Data(jsonDictionary: requestDictionary)
+        }
+        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
+            var serverError: FileProviderOneDriveError?
+            if let response = response as? HTTPURLResponse, response.statusCode >= 300, let code = FileProviderHTTPErrorCode(rawValue: response.statusCode) {
+                 serverError = FileProviderOneDriveError(code: code, path: sourcePath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
+            }
+            completionHandler?(serverError ?? error)
+            self.delegateNotify(operation, error: serverError ?? error)
+        })
+        task.taskDescription = operation.json
+        task.resume()
+        return RemoteOperationHandle(operationType: operation, tasks: [task])
+    }
+    
+    open func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        // check file is not a folder
+        guard (try? localFile.resourceValues(forKeys: [.fileResourceTypeKey]))?.fileResourceType ?? .unknown == .regular else {
+            dispatch_queue.async {
+                completionHandler?(self.throwError(localFile.path, code: URLError.fileIsDirectory))
+            }
+            return nil
+        }
+        
+        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
+        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
+            return nil
+        }
+        return upload_simple(toPath, localFile: localFile, overwrite: overwrite, operation: opType, completionHandler: completionHandler)
+    }
+    
+    open func copyItem(path: String, toLocalURL destURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let opType = FileOperationType.copy(source: path, destination: destURL.absoluteString)
+        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
+            return nil
+        }
+        var request = URLRequest(url: self.url(of: path, modifier: "content"))
+        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
+        let task = session.downloadTask(with: request)
+        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = completionHandler
+        downloadCompletionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { tempURL in
+            guard let httpResponse = task.response as? HTTPURLResponse , httpResponse.statusCode < 300 else {
+                let code = FileProviderHTTPErrorCode(rawValue: (task.response as? HTTPURLResponse)?.statusCode ?? -1)
+                let errorData : Data? = nil //Data(contentsOf: cacheURL) // TODO: Figure out how to get error response data for the error description
+                let serverError : FileProviderOneDriveError? = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: errorData ?? Data(), encoding: .utf8)) : nil
+                completionHandler?(serverError)
+                return
+            }
+            do {
+                try FileManager.default.moveItem(at: tempURL, to: destURL)
+                completionHandler?(nil)
+            } catch let e {
+                completionHandler?(e)
+            }
+        }
+        task.taskDescription = opType.json
+        task.resume()
+        return RemoteOperationHandle(operationType: opType, tasks: [task])
+    }
+}
+
+extension OneDriveFileProvider: FileProviderReadWrite {
+    open func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
+        if length == 0 || offset < 0 {
+            dispatch_queue.async {
+                completionHandler(Data(), nil)
+            }
+            return nil
+        }
+        
+        let opType = FileOperationType.fetch(path: path)
+        var request = URLRequest(url: self.url(of: path, modifier: "content"))
+        request.httpMethod = "GET"
+        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
+        if length > 0 {
+            request.setValue("bytes=\(offset)-\(offset + Int64(length) - 1)", forHTTPHeaderField: "Range")
+        } else if offset > 0 && length < 0 {
+            request.setValue("bytes=\(offset)-", forHTTPHeaderField: "Range")
+        }
+        let task = session.downloadTask(with: request)
+        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { error in
+            completionHandler(nil, error)
+        }
+        downloadCompletionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { tempURL in
+            guard let httpResponse = task.response as? HTTPURLResponse , httpResponse.statusCode < 300 else {
+                let code = FileProviderHTTPErrorCode(rawValue: (task.response as? HTTPURLResponse)?.statusCode ?? -1)
+                let errorData : Data? = nil //Data(contentsOf: cacheURL) // TODO: Figure out how to get error response data for the error description
+                let serverError : FileProviderOneDriveError? = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: errorData ?? Data(), encoding: .utf8)) : nil
+                completionHandler(nil, serverError)
+                return
+            }
+            do {
+                let data = try Data(contentsOf: tempURL)
+                completionHandler(data, nil)
+            } catch let e {
+                completionHandler(nil, e)
+            }
+        }
+        task.taskDescription = opType.json
+        task.resume()
+        return RemoteOperationHandle(operationType: opType, tasks: [task])
+    }
+    
+    open func writeContents(path: String, contents data: Data?, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let opType = FileOperationType.modify(path: path)
+        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
+            return nil
+        }
+        // FIXME: remove 150MB restriction
+        return upload_simple(path, data: data ?? Data(), overwrite: overwrite, operation: opType, completionHandler: completionHandler)
+    }
+    
+    fileprivate func registerNotifcation(path: String, eventHandler: (() -> Void)) {
+        /* There is two ways to monitor folders changing in OneDrive. Either using webooks
+         * which means you have to implement a server to translate it to push notifications
+         * or using apiv2 list_folder/longpoll method. The second one is implemeted here.
+         * Tough webhooks are much more efficient, longpoll is much simpler to implement!
+         * You can implemnt your own webhook service and replace this method accordingly.
+         */
+        NotImplemented()
+    }
+    fileprivate func unregisterNotifcation(path: String) {
+        NotImplemented()
+    }
+    
+    /**
+     Genrates a public url to a file to be shared with other users and can be downloaded without authentication.
+     
+     - Parameters:
+       - to: path of file, including file/directory name.
+       - completionHandler: a closure with result of directory entries or error.
+         `link`: a url returned by OneDrive to share.
+         `attribute`: `nil` for OneDrive.
+         `expiration`: `nil` for OneDrive, as it doesn't expires.
+         `error`: Error returned by OneDrive.
+     */
+    open func publicLink(to path: String, completionHandler: @escaping ((_ link: URL?, _ attribute: OneDriveFileObject?, _ expiration: Date?, _ error: Error?) -> Void)) {
+        var request = URLRequest(url: self.url(of: path, modifier: "action.createLink"))
+        request.httpMethod = "POST"
+        let requestDictionary: [String: AnyObject] = ["type": "view" as NSString]
+        request.httpBody = Data(jsonDictionary: requestDictionary)
+        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
+            var serverError: FileProviderOneDriveError?
+            var link: URL?
+            if let response = response as? HTTPURLResponse {
+                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
+                serverError = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
+                if let json = data?.deserializeJSON() {
+                    if let linkDic = json["link"] as? NSDictionary, let linkStr = linkDic["webUrl"] as? String {
+                        link = URL(string: linkStr)
+                    }
+                }
+            }
+            
+            completionHandler(link, nil, nil, serverError ?? error)
+        })
+        task.resume()
+    }
+}
+
+
+extension OneDriveFileProvider: ExtendedFileProvider {
+    open func thumbnailOfFileSupported(path: String) -> Bool {
+        return true
+    }
+    
+    open func propertiesOfFileSupported(path: String) -> Bool {
+        let fileExt = (path as NSString).pathExtension.lowercased()
+        switch fileExt {
+        case "jpg", "jpeg", "bmp", "gif", "png", "tif", "tiff":
+            return true
+        case "mp3", "aac", "m4a", "wma":
+            return true
+        case "mp4", "mpg", "3gp", "mov", "avi", "wmv":
+            return true
+        default:
+            return false
+        }
+    }
+    
+    open func thumbnailOfFile(path: String, dimension: CGSize?, completionHandler: @escaping ((_ image: ImageClass?, _ error: Error?) -> Void)) {
+        let url: URL
+        if let dimension = dimension {
+            url = self.url(of: path, modifier: "thumbnails/0/=c\(dimension.width)x\(dimension.height)/content")
+        } else {
+            url =  self.url(of: path, modifier: "thumbnails/0/small/content")
+        }
+        
+        var request = URLRequest(url: url)
+        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
+        let task = self.session.dataTask(with: request, completionHandler: { (data, response, error) in
+            var image: ImageClass? = nil
+            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
+                let responseError = FileProviderOneDriveError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8))
+                completionHandler(nil, responseError)
+                return
+            }
+            if let data = data {
+                image = ImageClass(data: data)
+            }
+            completionHandler(image, error)
+        })
+        task.resume()
+    }
+    
+    open func propertiesOfFile(path: String, completionHandler: @escaping ((_ propertiesDictionary: [String : Any], _ keys: [String], _ error: Error?) -> Void)) {
+        var request = URLRequest(url: url(of: path))
+        request.httpMethod = "GET"
+        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
+        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
+            var serverError: FileProviderOneDriveError?
+            var dic = [String: Any]()
+            var keys = [String]()
+            if let response = response as? HTTPURLResponse {
+                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
+                serverError = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
+                if let json = data?.deserializeJSON() {
+                    (dic, keys) = self.mapMediaInfo(json)
+                }
+            }
+            completionHandler(dic, keys, serverError ?? error)
+        })
+        task.resume()
+    }
+}
+
+extension OneDriveFileProvider: FileProvider { }
@@ -8,16 +8,14 @@

 import Foundation

-public struct FileProviderOneDriveError: Error, CustomStringConvertible {
+/// Error returned by OneDrive server when trying to access or do operations on a file or folder.
+public struct FileProviderOneDriveError: FileProviderHTTPError {
    public let code: FileProviderHTTPErrorCode
    public let path: String
    public let errorDescription: String?
-    
-    public var description: String {
-        return code.description
-    }
 }

+/// Containts path, url and attributes of a OneDrive file or resource.
 public final class OneDriveFileObject: FileObject {
    internal init(baseURL: URL?, name: String, path: String) {
        var rpath = path
@@ -29,60 +27,62 @@ public final class OneDriveFileObject: FileObject {
    }
    
    internal convenience init? (baseURL: URL?, drive: String, jsonStr: String) {
-        guard let json = jsonToDictionary(jsonStr) else { return nil }
+        guard let json = jsonStr.deserializeJSON() else { return nil }
        self.init(baseURL: baseURL, drive: drive, json: json)
    }
    
    internal convenience init? (baseURL: URL?, drive: String, json: [String: AnyObject]) {
        guard let name = json["name"] as? String else { return nil }
        guard let path = (json["parentReference"] as? NSDictionary)?["path"] as? String else { return nil }
-        let lPath = path.replacingOccurrences(of: "/drive/\(drive):", with: "/", options: .anchored, range: nil)
+        var lPath = path.replacingOccurrences(of: "/drive/\(drive)", with: "/", options: .anchored, range: nil)
+        lPath = lPath.replacingOccurrences(of: "/:", with: "", options: .anchored)
+        lPath = lPath.replacingOccurrences(of: "//", with: "", options: .anchored)
        self.init(baseURL: baseURL, name: name, path: lPath)
        self.size = (json["size"] as? NSNumber)?.int64Value ?? -1
-        self.modifiedDate = resolve(dateString: json["lastModifiedDateTime"] as? String ?? "")
-        self.creationDate = resolve(dateString: json["createdDateTime"] as? String ?? "")
+        self.modifiedDate = Date(rfcString: json["lastModifiedDateTime"] as? String ?? "")
+        self.creationDate = Date(rfcString: json["createdDateTime"] as? String ?? "")
        self.type = (json["folder"] as? String) != nil ? .directory : .regular
        self.id = json["id"] as? String
        self.entryTag = json["eTag"] as? String
    }
    
+    /// The document identifier is a value assigned by the OneDrive to a file.
+    /// This value is used to identify the document regardless of where it is moved on a volume.
+    /// The identifier persists across system restarts.
    open internal(set) var id: String? {
        get {
-            return allValues["NSURLDocumentIdentifyKey"] as? String
+            return allValues[.documentIdentifierKey] as? String
        }
        set {
-            allValues["NSURLDocumentIdentifyKey"] = newValue
+            allValues[.documentIdentifierKey] = newValue
        }
    }
    
+    /// MIME type of file contents returned by OneDrive server.
    open internal(set) var contentType: String {
        get {
-            return allValues["NSURLContentTypeKey"] as? String ?? ""
+            return allValues[.mimeTypeKey] as? String ?? ""
        }
        set {
-            allValues["NSURLContentTypeKey"] = newValue
+            allValues[.mimeTypeKey] = newValue
        }
    }
    
+    /// HTTP E-Tag, can be used to mark changed files.
    open internal(set) var entryTag: String? {
        get {
-            return allValues["NSURLEntryTagKey"] as? String
+            return allValues[.entryTagKey] as? String
        }
        set {
-            allValues["NSURLEntryTagKey"] = newValue
+            allValues[.entryTagKey] = newValue
        }
    }
 }

 // codebeat:disable[ARITY]
 internal extension OneDriveFileProvider {
-    func list(_ path: String, cursor: String? = nil, prevContents: [OneDriveFileObject] = [], completionHandler: @escaping ((_ contents: [FileObject], _ cursor: String?, _ error: Error?) -> Void)) {
-        let url: URL
-        if let cursor = cursor {
-            url = URL(string: cursor)!
-        } else {
-            url = URL(string: escaped(path: path), relativeTo: driveURL)!
-        }
+    func list(_ path: String, cursor: URL? = nil, prevContents: [OneDriveFileObject] = [], completionHandler: @escaping ((_ contents: [FileObject], _ cursor: String?, _ error: Error?) -> Void)) {
+        let url = cursor ?? self.url(of: path, modifier: "children")
        var request = URLRequest(url: url)
        request.httpMethod = "GET"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
@@ -92,15 +92,14 @@ internal extension OneDriveFileProvider {
            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
                responseError = FileProviderOneDriveError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8))
            }
-            if let data = data, let jsonStr = String(data: data, encoding: .utf8) {
-                let json = jsonToDictionary(jsonStr)
-                if let entries = json?["value"] as? [AnyObject] , entries.count > 0 {
+            if let json = data?.deserializeJSON() {
+                if let entries = json["value"] as? [AnyObject] , entries.count > 0 {
                    for entry in entries {
                        if let entry = entry as? [String: AnyObject], let file = OneDriveFileObject(baseURL: self.baseURL, drive: self.drive, json: entry) {
                            files.append(file)
                        }
                    }
-                    let ncursor = json?["@odata.nextLink"] as? String
+                    let ncursor: URL? = (json["@odata.nextLink"] as? String).flatMap { URL(string: $0) }
                    let hasmore = ncursor != nil
                    if hasmore {
                        self.list(path, cursor: ncursor, prevContents: files, completionHandler: completionHandler)
@@ -114,35 +113,8 @@ internal extension OneDriveFileProvider {
        task.resume()
    }
    
-    func upload_simple(_ targetPath: String, data: Data, modifiedDate: Date = Date(), overwrite: Bool, operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        if data.count > 100 * 1024 * 1024 {
-            let error = FileProviderOneDriveError(code: .payloadTooLarge, path: targetPath, errorDescription: nil)
-            completionHandler?(error)
-            self.delegateNotify(.create(path: targetPath), error: error)
-            return nil
-        }
-        let queryStr = overwrite ? "" : "?@name.conflictBehavior=fail"
-        let url = URL(string: escaped(path: targetPath) + ":/content" + queryStr, relativeTo: driveURL)!
-        var request = URLRequest(url: url)
-        request.httpMethod = "PUT"
-        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        request.setValue("application/octet-stream", forHTTPHeaderField: "Content-Type")
-        request.httpBody = data
-        let task = session.uploadTask(with: request, from: data, completionHandler: { (data, response, error) in
-            var responseError: FileProviderOneDriveError?
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderOneDriveError(code: rCode, path: targetPath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
-            }
-            completionHandler?(responseError ?? error)
-            self.delegateNotify(.create(path: targetPath), error: responseError ?? error)
-        })
-        task.taskDescription = operation.json
-        task.resume()
-        return RemoteOperationHandle(operationType: operation, tasks: [task])
-    }
-    
-    func upload_simple(_ targetPath: String, localFile: URL, modifiedDate: Date = Date(), overwrite: Bool, operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let size = (try? localFile.resourceValues(forKeys: [.fileSizeKey]))?.fileSize ?? -1
+    func upload_simple(_ targetPath: String, data: Data? = nil , localFile: URL? = nil, modifiedDate: Date = Date(), overwrite: Bool, operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let size = data?.count ?? (try? localFile?.resourceValues(forKeys: [.fileSizeKey]))??.fileSize ?? -1
        if size > 100 * 1024 * 1024 {
            let error = FileProviderOneDriveError(code: .payloadTooLarge, path: targetPath, errorDescription: nil)
            completionHandler?(error)
@@ -150,33 +122,38 @@ internal extension OneDriveFileProvider {
            return nil
        }
        let queryStr = overwrite ? "" : "?@name.conflictBehavior=fail"
-        let url = URL(string: escaped(path: targetPath) + ":/content" + queryStr, relativeTo: driveURL)!
+        let url = self.url(of: targetPath, modifier: "content\(queryStr)")
        var request = URLRequest(url: url)
        request.httpMethod = "PUT"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        request.setValue("application/octet-stream", forHTTPHeaderField: "Content-Type")
-        let task = session.uploadTask(with: request, fromFile: localFile, completionHandler: { (data, response, error) in
+        let task: URLSessionUploadTask
+        if let data = data {
+            task = session.uploadTask(with: request, from: data)
+        } else if  let localFile = localFile {
+            task = session.uploadTask(with: request, fromFile: localFile)
+        } else {
+            return nil
+        }
+        
+        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { [weak self] error in
            var responseError: FileProviderOneDriveError?
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderOneDriveError(code: rCode, path: targetPath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
+            if let code = (task.response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
+                // We can't fetch server result from delegate!
+                responseError = FileProviderOneDriveError(code: rCode, path: targetPath, errorDescription: nil)
            }
            completionHandler?(responseError ?? error)
-            self.delegateNotify(.create(path: targetPath), error: responseError ?? error)
-        })
+            self?.delegateNotify(.create(path: targetPath), error: responseError ?? error)
+        }
        task.taskDescription = operation.json
        task.resume()
        return RemoteOperationHandle(operationType: operation, tasks: [task])
    }
    
-    func search(_ startPath: String = "", query: String, next: String? = nil, foundItem:@escaping ((_ file: OneDriveFileObject) -> Void), completionHandler: @escaping ((_ error: Error?) -> Void)) {
+    func search(_ startPath: String = "", query: String, next: URL? = nil, foundItem:@escaping ((_ file: OneDriveFileObject) -> Void), completionHandler: @escaping ((_ error: Error?) -> Void)) {
        let url: URL
-        if let next = next {
-            url = URL(string: next)!
-        } else if self.escaped(path: startPath) == "" {
-            url = URL(string: "/drive/\(drive)/view.search?q=\(query)", relativeTo: baseURL)!
-        } else {
-            url = URL(string: "\(escaped(path: startPath))/view.search?q=\(query)", relativeTo: driveURL)!
-        }
+        let q = query.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)!
+        url = next ?? self.url(of: startPath, modifier: "view.search?q=\(q)")
        var request = URLRequest(url: url)
        request.httpMethod = "GET"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
@@ -186,17 +163,15 @@ internal extension OneDriveFileProvider {
            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
                responseError = FileProviderOneDriveError(code: rCode, path: startPath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
            }
-            if let data = data, let jsonStr = String(data: data, encoding: .utf8) {
-                let json = jsonToDictionary(jsonStr)
-                if let entries = json?["value"] as? [AnyObject] , entries.count > 0 {
+            if let json = data?.deserializeJSON() {
+                if let entries = json["value"] as? [AnyObject] , entries.count > 0 {
                    for entry in entries {
                        if let entry = entry as? [String: AnyObject], let file = OneDriveFileObject(baseURL: self.baseURL, drive: self.drive, json: entry) {
                            foundItem(file)
                        }
                    }
-                    let next = json?["@odata.nextLink"] as? String
-                    let hasmore = next != nil
-                    if hasmore, let next = next {
+                    let next: URL? = (json["@odata.nextLink"] as? String).flatMap { URL(string: $0) }
+                    if let next = next {
                        self.search(startPath, query: query, next: next, foundItem: foundItem, completionHandler: completionHandler)
                    } else {
                        completionHandler(responseError ?? error)
@@ -235,72 +210,51 @@ internal extension OneDriveFileProvider {
        var dic = [String: Any]()
        var keys = [String]()
        
+        func add(key: String, value: Any?) {
+            if let value = value {
+                keys.append(key)
+                dic[key] = value
+            }
+        }
+        
        if let parent = json["image"] as? [String: Any] ?? json["video"] as? [String: Any], let height = parent["height"] as? UInt64, let width = parent["width"] as? UInt64 {
-            keys.append("Dimensions")
-            dic["Dimensions"] = "\(width)x\(height)"
+            add(key: "Dimensions", value: "\(width)x\(height)")
        }
        if let location = json["location"] as? [String: Any], let latitude = location["latitude"] as? Double, let longitude = location["longitude"] as? Double {
-            
            OneDriveFileProvider.decimalFormatter.numberStyle = .decimal
            OneDriveFileProvider.decimalFormatter.maximumFractionDigits = 5
-            keys.append("Location")
-            let latStr = OneDriveFileProvider.decimalFormatter.string(from: NSNumber(value: latitude))
-            let longStr = OneDriveFileProvider.decimalFormatter.string(from: NSNumber(value: longitude))
-            dic["Location"] = "\(latStr), \(longStr)"
+            let latStr = OneDriveFileProvider.decimalFormatter.string(from: NSNumber(value: latitude))!
+            let longStr = OneDriveFileProvider.decimalFormatter.string(from: NSNumber(value: longitude))!
+            add(key: "Location", value: "\(latStr), \(longStr)")
        }
        if let parent = json["image"] as? [String: Any] ?? json["video"] as? [String: Any], let duration = parent["duration"] as? UInt64 {
-            keys.append("Duration")
-            dic["Duration"] = OneDriveFileProvider.formatshort(interval: TimeInterval(duration) / 1000)
+            add(key: "Duration", value: (TimeInterval(duration) / 1000).formatshort)
        }
-        if let timeTakenStr = json["takenDateTime"] as? String, let timeTaken = resolve(dateString: timeTakenStr) {
-            keys.append("Date taken")
+        if let timeTakenStr = json["takenDateTime"] as? String, let timeTaken = Date(rfcString: timeTakenStr) {
            OneDriveFileProvider.dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
-            dic["Date taken"] = OneDriveFileProvider.dateFormatter.string(from: timeTaken)
+            add(key: "Date taken", value:  OneDriveFileProvider.dateFormatter.string(from: timeTaken))
        }
        
        if let photo = json["photo"] as? [String: Any] {
-            if let devicemake = photo["cameraMake"] as? String {
-                keys.append("Device make")
-                dic["Device make"] = devicemake
-            }
-            if let devicemodel = photo["cameraModel"] as? String {
-                keys.append("Device model")
-                dic["Device model"] = devicemodel
-            }
-            if let focallen = photo["focalLength"] as? Double {
-                keys.append("Focal length")
-                dic["Focal length"] = focallen
-            }
-            if let fnum = photo["fNumber"] as? Double {
-                keys.append("F number")
-                dic["F number"] = fnum
-            }
+            add(key: "Device make", value: photo["cameraMake"] as? String)
+            add(key: "Device model", value: photo["cameraModel"] as? String)
+            add(key: "focalLength", value: photo["focalLength"] as? Double)
+            add(key: "fNumber", value: photo["fNumber"] as? Double)
            if let expNom = photo["exposureNumerator"] as? Double, let expDen = photo["exposureDenominator"] as? Double {
-                keys.append("Exposure time")
-                dic["Exposure time"] = "\(Int(expNom))/\(Int(expDen))"
+                add(key: "Exposure time", value: "\(Int(expNom))/\(Int(expDen))")
            }
-            if let iso = photo["iso"] as? Int64 {
-                keys.append("ISO speed")
-                dic["ISO speed"] = iso
-            }
-
+            add(key: "ISO speed", value: photo["iso"] as? Int64)
        }
        
        if let audio = json["audio"] as? [String: Any] {
            for (key, value) in audio {
                if key == "bitrate" || key == "isVariableBitrate" { continue }
                let casedKey = spaceCamelCase(key)
-                keys.append(casedKey)
-                dic[casedKey] = value
+                add(key: casedKey, value: value)
            }
        }
        
-        if let video = json["video"] as? [String: Any] {
-            if let bitRate = video["bitrate"] as? Int {
-                keys.append("Bitrate")
-                dic["Bitrate"] = bitRate
-            }
-        }
+        add(key: "Bitrate", value: (json["video"] as? NSDictionary)?["bitrate"] as? Int)
        
        return (dic, keys)
    }
@@ -8,41 +8,49 @@

 import Foundation

+/// Allows to get progress or cancel an in-progress operation, for remote, `URLSession` based providers.
+/// This class keeps strong reference to tasks.
 open class RemoteOperationHandle: OperationHandle {
    
-    internal var tasks: [Weak<URLSessionTask>]
+    internal var tasks: [URLSessionTask]
    
    open private(set) var operationType: FileOperationType
    
    init(operationType: FileOperationType, tasks: [URLSessionTask]) {
        self.operationType = operationType
-        self.tasks = tasks.map { Weak<URLSessionTask>($0) }
+        self.tasks = tasks
    }
    
    internal func add(task: URLSessionTask) {
-        tasks.append(Weak<URLSessionTask>(task))
+        tasks.append(task)
    }
    
-    private func reape() {
-        self.tasks = tasks.filter { $0.value != nil }
+    internal func reape() {
+        self.tasks = tasks.filter { $0.state != .completed }
    }
    
    open var bytesSoFar: Int64 {
        return tasks.reduce(0) {
-            if let task = $1.value as? URLSessionUploadTask {
+            switch $1 {
+            case let task as URLSessionUploadTask:
                return $0 + task.countOfBytesSent
-            } else {
-                return $0 + ($1.value?.countOfBytesReceived ?? 0)
+            case let task as FileProviderStreamTask:
+                return $0 + task.countOfBytesSent + task.countOfBytesReceived
+            default:
+                return $0 + $1.countOfBytesReceived
            }
        }
    }
    
    open var totalBytes: Int64 {
        return tasks.reduce(0) {
-            if let task = $1.value as? URLSessionUploadTask {
+            switch $1 {
+            case let task as URLSessionUploadTask:
                return $0 + task.countOfBytesExpectedToSend
-            } else {
-                return $0 + ($1.value?.countOfBytesExpectedToSend ?? 0)
+            case let task as FileProviderStreamTask:
+                return $0 + task.countOfBytesExpectedToSend + task.countOfBytesExpectedToReceive
+            default:
+                return $0 + $1.countOfBytesExpectedToReceive
            }
        }
    }
@@ -50,155 +58,299 @@ open class RemoteOperationHandle: OperationHandle {
    open func cancel() -> Bool {
        var canceled = false
        for taskbox in tasks {
-            taskbox.value?.cancel()
+            taskbox.cancel()
            canceled = true
        }
        return canceled
    }
    
    open var inProgress: Bool {
-        return tasks.reduce(false) { $0 || $1.value?.state ?? .canceling == .running }
+        return tasks.reduce(false) { $0 || $1.state == .running }
    }
 }

-class SessionDelegate: NSObject, URLSessionDataDelegate, URLSessionDownloadDelegate {
+/// A protocol defines properties for errors returned by HTTP/S based providers.
+/// Including Dropbox, OneDrive and WebDAV.
+public protocol FileProviderHTTPError: Error, CustomStringConvertible {
+    /// HTTP status code returned for error by server.
+    var code: FileProviderHTTPErrorCode { get }
+    /// Path of file/folder casued that error
+    var path: String { get }
+    /// Contents returned by server as error description
+    var errorDescription: String? { get }
+}
+
+extension FileProviderHTTPError {
+    public var description: String {
+        return code.description
+    }
    
-    weak var fileProvider: FileProvider?
+    public var localizedDescription: String {
+        return description
+    }
+}
+
+internal var completionHandlersForTasks = [String: [Int: SimpleCompletionHandler]]()
+internal var downloadCompletionHandlersForTasks = [String: [Int: (URL) -> Void]]()
+internal var dataCompletionHandlersForTasks = [String: [Int: (Data) -> Void]]()
+
+internal func initEmptySessionHandler(_ uuid: String) {
+    completionHandlersForTasks[uuid] = [:]
+    downloadCompletionHandlersForTasks[uuid] = [:]
+    dataCompletionHandlersForTasks[uuid] = [:]
+}
+
+internal func removeSessionHandler(for uuid: String) {
+    _ = completionHandlersForTasks.removeValue(forKey: uuid)
+    _ = downloadCompletionHandlersForTasks.removeValue(forKey: uuid)
+    _ = dataCompletionHandlersForTasks.removeValue(forKey: uuid)
+}
+
+/// All objects set to `FileProviderRemote.session` must be an instance of this class
+final public class SessionDelegate: NSObject, URLSessionDataDelegate, URLSessionDownloadDelegate, URLSessionStreamDelegate {
+    
+    weak var fileProvider: (FileProviderBasicRemote & FileProviderOperations)?
    var credential: URLCredential?
    
-    var finishDownloadHandler: ((_ session: Foundation.URLSession, _ downloadTask: URLSessionDownloadTask, _ didFinishDownloadingToURL: URL) -> Void)?
-    var didSendDataHandler: ((_ session: Foundation.URLSession, _ task: URLSessionTask, _ bytesSent: Int64, _ totalBytesSent: Int64, _ totalBytesExpectedToSend: Int64) -> Void)?
-    var didReceivedData: ((_ session: Foundation.URLSession, _ downloadTask: URLSessionDownloadTask, _ bytesWritten: Int64, _ totalBytesWritten: Int64, _ totalBytesExpectedToWrite: Int64) -> Void)?
+    /// Forwardng URLSessionDownloadTaskDelegate call
+    public var finishDownloadHandler: ((_ session: URLSession, _ downloadTask: URLSessionDownloadTask, _ didFinishDownloadingToURL: URL) -> Void)?
+    /// Forwardng URLSessionTaskDelegate call
+    public var didSendDataHandler: ((_ session: URLSession, _ task: URLSessionTask, _ bytesSent: Int64, _ totalBytesSent: Int64, _ totalBytesExpectedToSend: Int64) -> Void)?
+    /// Forwardng URLSessionDownloadTaskDelegate call
+    public var didReceivedData: ((_ session: URLSession, _ downloadTask: URLSessionDownloadTask, _ bytesWritten: Int64, _ totalBytesWritten: Int64, _ totalBytesExpectedToWrite: Int64) -> Void)?
+    /// Forwardng URLSessionStreamTaskDelegate call
+    public var didBecomeStream :((_ session: URLSession, _ taskId: Int, _ didBecome: InputStream, _ outputStream: OutputStream) -> Void)?
    
-    init(fileProvider: FileProvider, credential: URLCredential?) {
+    public init(fileProvider: FileProviderBasicRemote & FileProviderOperations) {
        self.fileProvider = fileProvider
-        self.credential = credential
+        self.credential = fileProvider.credential
    }
    
    // codebeat:disable[ARITY]
-    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
-        self.finishDownloadHandler?(session, downloadTask, location)
-        return
+    public func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
+        if !(error == nil && task is URLSessionDownloadTask) {
+            let completionHandler = completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] ?? nil
+            completionHandler?(error)
+            _ = completionHandlersForTasks[session.sessionDescription!]?.removeValue(forKey: task.taskIdentifier)
+        }
+        
+        guard let json = task.taskDescription?.deserializeJSON(),
+            let op = FileOperationType(json: json), let fileProvider = fileProvider else {
+                return
+        }
+        
+        if !(task is URLSessionDownloadTask), case FileOperationType.fetch = op {
+            return
+        }
+        DispatchQueue.main.async {
+            if error != nil {
+                fileProvider.delegate?.fileproviderFailed(fileProvider, operation: op)
+            } else {
+                fileProvider.delegate?.fileproviderSucceed(fileProvider, operation: op)
+            }
+        }
    }
    
-    func urlSession(_ session: URLSession, task: URLSessionTask, didSendBodyData bytesSent: Int64, totalBytesSent: Int64, totalBytesExpectedToSend: Int64) {
+    public func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
+        let completionHandler = dataCompletionHandlersForTasks[session.sessionDescription!]?[dataTask.taskIdentifier] ?? nil
+        completionHandler?(data)
+        _ = dataCompletionHandlersForTasks[session.sessionDescription!]?.removeValue(forKey: dataTask.taskIdentifier)
+    }
+    
+    public func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
+        self.finishDownloadHandler?(session, downloadTask, location)
+        
+        let dcompletionHandler = downloadCompletionHandlersForTasks[session.sessionDescription!]?[downloadTask.taskIdentifier]
+        dcompletionHandler?(location)
+        _ = downloadCompletionHandlersForTasks[session.sessionDescription!]?.removeValue(forKey: downloadTask.taskIdentifier)
+        _ = completionHandlersForTasks[session.sessionDescription!]?.removeValue(forKey: downloadTask.taskIdentifier)
+    }
+    
+    public func urlSession(_ session: URLSession, task: URLSessionTask, didSendBodyData bytesSent: Int64, totalBytesSent: Int64, totalBytesExpectedToSend: Int64) {
        self.didSendDataHandler?(session, task, bytesSent, totalBytesSent, totalBytesExpectedToSend)
        
-        guard let desc = task.taskDescription, let json = jsonToDictionary(desc) else {
+        guard let json = task.taskDescription?.deserializeJSON(),
+              let op = FileOperationType(json: json), let fileProvider = fileProvider else {
            return
        }
-        guard let type = json["type"] as? String, let source = json["source"] as? String else {
-            return
-        }
-        let dest = json["dest"] as? String
-        let op : FileOperationType
-        switch type {
-        case "Create":
-            op = .create(path: source)
-        case "Copy":
-            guard let dest = dest else { return }
-            op = .copy(source: source, destination: dest)
-        case "Move":
-            guard let dest = dest else { return }
-            op = .move(source: source, destination: dest)
-        case "Modify":
-            op = .modify(path: source)
-        case "Remove":
-            op = .remove(path: source)
-        case "Link":
-            guard let dest = dest else { return }
-            op = .link(link: source, target: dest)
+        
+        switch op {
+        case .create(path: let path):
+            if path.hasSuffix("/") { return }
+        case .modify:
+            break
        default:
            return
        }
        
        let progress = Float(totalBytesSent) / Float(totalBytesExpectedToSend)
        
-        fileProvider?.delegate?.fileproviderProgress(fileProvider!, operation: op, progress: progress)
+        DispatchQueue.main.async {
+            fileProvider.delegate?.fileproviderProgress(fileProvider, operation: op, progress: progress)
+        }
    }
    
-    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
+    public func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
        self.didReceivedData?(session, downloadTask, bytesWritten, totalBytesWritten, totalBytesExpectedToWrite)
        
-        guard let desc = downloadTask.taskDescription, let json = jsonToDictionary(desc), let source = json["source"] as? String, let dest = json["dest"] as? String else {
+        guard let json = downloadTask.taskDescription?.deserializeJSON(),
+              let op = FileOperationType(json: json), let fileProvider = fileProvider else {
            return
        }
        
-        fileProvider?.delegate?.fileproviderProgress(fileProvider!, operation: .copy(source: source, destination: dest), progress: Float(totalBytesWritten) / Float(totalBytesExpectedToWrite))
+        DispatchQueue.main.async {
+            fileProvider.delegate?.fileproviderProgress(fileProvider, operation: op, progress: Float(totalBytesWritten) / Float(totalBytesExpectedToWrite))
+        }
    }
    
-    func urlSession(_ session: URLSession, task: URLSessionTask, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
-        let deposition: Foundation.URLSession.AuthChallengeDisposition = credential != nil ? .useCredential : .performDefaultHandling
-        completionHandler(deposition, credential)
+    public func urlSession(_ session: URLSession, task: URLSessionTask, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
+        authenticate(didReceive: challenge, completionHandler: completionHandler)
    }
    
-    func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
-        let deposition: Foundation.URLSession.AuthChallengeDisposition = credential != nil ? .useCredential : .performDefaultHandling
-        completionHandler(deposition, credential)
+    public func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
+        authenticate(didReceive: challenge, completionHandler: completionHandler)
+    }
+    
+    func authenticate(didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
+        switch (challenge.previousFailureCount, credential != nil) {
+        case (0...1, true):
+            completionHandler(.useCredential, credential)
+        case (0, false):
+            completionHandler(.useCredential, challenge.proposedCredential)
+        default:
+            completionHandler(.performDefaultHandling, nil)
+        }
+    }
+    
+    @available(iOS 9.0, macOS 10.11, *)
+    public func urlSession(_ session: URLSession, streamTask: URLSessionStreamTask, didBecome inputStream: InputStream, outputStream: OutputStream) {
+        self.didBecomeStream?(session, streamTask.taskIdentifier, inputStream, outputStream)
    }
 }

-public enum FileProviderHTTPErrorCode: Int {
+/// HTTP status codes as an enum.
+public enum FileProviderHTTPErrorCode: Int, CustomStringConvertible {
+    /// `Continue` informational status with HTTP code 100
    case `continue` = 100
+    /// `Switching Protocols` informational status with HTTP code 101
    case switchingProtocols = 101
+    /// `Processing` informational status with HTTP code 102
    case processing = 102
+    /// `OK` success status with HTTP code 200
    case ok = 200
+    /// `Created` success status with HTTP code 201
    case created = 201
+    /// `Accepted` success status with HTTP code 202
    case accepted = 202
+    /// `Non Authoritative Information` success status with HTTP code 203
    case nonAuthoritativeInformation = 203
+    /// `No Content` success status with HTTP code 204
    case noContent = 204
+    /// `ResetcContent` success status with HTTP code 205
    case resetContent = 205
+    /// `Partial Content` success status with HTTP code 206
    case partialContent = 206
+    /// `Multi Status` success status with HTTP code 207
    case multiStatus = 207
+    /// `Already Reported` success status with HTTP code 208
    case alreadyReported = 208
+    /// `IM Used` success status with HTTP code 226
    case imUsed = 226
+    /// `Multiple Choices` redirection status with HTTP code 300
    case multipleChoices = 300
+    /// `Moved Permanently` redirection status with HTTP code 301
    case movedPermanently = 301
+    /// `Found` redirection status with HTTP code 302
    case found = 302
+    /// `See Other` redirection status with HTTP code 303
    case seeOther = 303
+    /// `Not Modified` redirection status with HTTP code 304
    case notModified = 304
+    /// `Use Proxy` redirection status with HTTP code 305
    case useProxy = 305
+    /// `Switch Proxy` redirection status with HTTP code 306
    case switchProxy = 306
+    /// `Temporary Redirect` redirection status with HTTP code 307
    case temporaryRedirect = 307
+    /// `Permanent Redirect` redirection status with HTTP code 308
    case permanentRedirect = 308
+    /// `Bad Request` client error status with HTTP code 400
    case badRequest = 400
+    /// `Unauthorized` client error status with HTTP code 401
    case unauthorized = 401
+    /// `Payment Required` client error status with HTTP code 402
    case paymentRequired = 402
+    /// `Forbidden` client error status with HTTP code 403
    case forbidden = 403
+    /// `Not Found` client error status with HTTP code 404
    case notFound = 404
+    /// `Method Not Allowed` client error status with HTTP code 405
    case methodNotAllowed = 405
+    /// `Not Acceptable` client error status with HTTP code 406
    case notAcceptable = 406
+    /// `Proxy Authentication Required` client error status with HTTP code 407
    case proxyAuthenticationRequired = 407
+    /// `Request Timeout` client error status with HTTP code 408
    case requestTimeout = 408
+    /// `Conflict` client error status with HTTP code 409
    case conflict = 409
+    /// `Gone` client error status with HTTP code 410
    case gone = 410
+    /// `Length Required` client error status with HTTP code 411
    case lengthRequired = 411
+    /// `Precondition Failed` client error status with HTTP code 412
    case preconditionFailed = 412
+    /// `Payload Too Large` client error status with HTTP code 413
    case payloadTooLarge = 413
+    /// `URI Too Long` client error status with HTTP code 414
    case uriTooLong = 414
+    /// `Unsupported Media Type` status with HTTP code 415
    case unsupportedMediaType = 415
+    /// `Range Not Satisfiable` client error status with HTTP code 416
    case rangeNotSatisfiable = 416
+    /// `Expectation Failed` client error status with HTTP code 417
    case expectationFailed = 417
+    /// `Misdirected Request` client error status with HTTP code 421
    case misdirectedRequest = 421
+    /// `Unprocessable Entity` client error status with HTTP code 422
    case unprocessableEntity = 422
+    /// `Locked` client error status with HTTP code 423
    case locked = 423
+    /// `Failed Dependency` client error status with HTTP code 424
    case failedDependency = 424
+    /// `Unordered Collection` client error status with HTTP code 425
    case unorderedCollection = 425
+    /// `Upgrade Required` client error status with HTTP code 426
    case upgradeRequired = 426
+    /// `Precondition Required` client error status with HTTP code 428
    case preconditionRequired = 428
+    /// `Too Many Requests` client error status with HTTP code 429
    case tooManyRequests = 429
+    /// `Request Header Fields Too Large` client error status with HTTP code 431
    case requestHeaderFieldsTooLarge = 431
+    /// `Unavailable For Legal Reasons` client error status with HTTP code 451
    case unavailableForLegalReasons = 451
+    /// `Internal Server Error` server error status with HTTP code 500
    case internalServerError = 500
+    /// `Bad Gateway` server error status with HTTP code 502
    case badGateway = 502
+    /// `Service Unavailable` server error status with HTTP code 503
    case serviceUnavailable = 503
+    /// `Gateway Timeout` server error status with HTTP code 504
    case gatewayTimeout = 504
+    /// `HTTP Version Not Supported` server error status with HTTP code 505
    case httpVersionNotSupported = 505
-    case variantlsoNegotiates = 506
+    /// `Variant Also Negotiates` server error status with HTTP code 506
+    case variantAlsoNegotiates = 506
+    /// `Insufficient Storage` server error status with HTTP code 507
    case insufficientStorage = 507
+    /// `Loop Detected` server error status with HTTP code 508
    case loopDetected = 508
+    /// `Bandwidth Limit Exceeded` server error status with HTTP code 509
    case bandwidthLimitExceeded = 509
+    /// `Not Extended` server error status with HTTP code 510
    case notExtended = 510
+    /// `Network Authentication Required` server error status with HTTP code 511
    case networkAuthenticationRequired = 511
    
    fileprivate static let status1xx: [Int: String] = [100: "Continue", 101: "Switching Protocols", 102: "Processing"]
@@ -219,6 +371,7 @@ public enum FileProviderHTTPErrorCode: Int {
        }
    }
    
+    /// Description of status based on first digit which indicated fail or success.
    public var typeDescription: String {
        switch self.rawValue {
        case 100...199: return "Informational"
@@ -226,7 +379,7 @@ public enum FileProviderHTTPErrorCode: Int {
        case 300...399: return "Redirection"
        case 400...499: return "Client Error"
        case 500...599: return "Server Error"
-        default: return "Server Error"
+        default: return "Unknown Error"
        }
    }
 }
@@ -11,11 +11,11 @@ import Foundation
 // This client implementation is for little-endian platform, namely x86, x64 & arm
 // For big-endian platforms like PowerPC, there must be a huge overhaul

-protocol SMBProtocolClientDelegate: class {
-    func receivedResponse(client: SMB2ProtocolClient, response: SMBResponse, for: SMBRequest)
+protocol FileProviderSMBTaskDelegate: class {
+    func receivedResponse(client: FileProviderSMBTask, response: SMBResponse, for: SMBRequest)
 }

-class SMB2ProtocolClient: FPSStreamTask {
+class FileProviderSMBTask: FileProviderStreamTask {
    var timeout: TimeInterval = 30
    
    private(set) var lastMessageID: UInt64 = 0
@@ -31,14 +31,14 @@ class SMB2ProtocolClient: FPSStreamTask {
    private(set) var requestStack = [Int: SMBRequest]()
    private(set) var responseStack = [Int: SMBResponse]()
    
-    weak var delegate: SMBProtocolClientDelegate?
+    weak var delegate: FileProviderSMBTaskDelegate?
    
    func sendNegotiate(completionHandler: SimpleCompletionHandler) -> UInt64 {
        let mId = messageId()
        let smbHeader = SMB2.Header(command: .NEGOTIATE, creditRequestResponse: UInt16(126), messageId: mId, treeId: UInt32(0), sessionId: UInt64(0))
        let msg = SMB2.NegotiateRequest()
        let data = createSMB2Message(header: smbHeader, message: msg)
-        self.writeData(data, timeout: 0, completionHandler: { (e) in
+        self.write(data, timeout: timeout, completionHandler: { (e) in
            completionHandler?(e)
        })
        return mId
@@ -50,9 +50,9 @@ class SMB2ProtocolClient: FPSStreamTask {
        let smbHeader = SMB2.Header(command: SMB2.Command.SESSION_SETUP, creditRequestResponse: credit, messageId: mId, treeId: UInt32(0), sessionId: sessionId)
        let msg = SMB2.SessionSetupRequest(singing: [])
        let data = createSMB2Message(header: smbHeader, message: msg)
-        self.writeData(data, timeout: 0, completionHandler: { (e) in
+        self.write(data, timeout: timeout, completionHandler: { (e) in
            if self.sessionId == 0 {
-                self.readData(OfMinLength: 64, maxLength: 65536, timeout: self.timeout, completionHandler: { (data, eof, e2) in
+                self.readData(ofMinLength: 64, maxLength: 65536, timeout: self.timeout, completionHandler: { (data, eof, e2) in
                    // TODO: set session id
                    completionHandler?(e2 ?? e)
                })
@@ -68,15 +68,12 @@ class SMB2ProtocolClient: FPSStreamTask {
        }
        let mId = messageId()
        let smbHeader = SMB2.Header(command: .TREE_CONNECT, creditRequestResponse: 123, messageId: mId, treeId: 0, sessionId: sessionId)
-        var share = ""
        let cmp = url.pathComponents
-        if cmp.count > 0 {
-            share = cmp[0]
-        }
+        let share = cmp.first ?? ""
        let tcHeader = SMB2.TreeConnectRequest.Header(flags: [])
        let msg = SMB2.TreeConnectRequest(header: tcHeader, host: host, share: share)
        let data = createSMB2Message(header: smbHeader, message: msg!)
-        self.writeData(data, timeout: 0, completionHandler: { (e) in
+        self.write(data, timeout: timeout, completionHandler: { (e) in
            completionHandler?(e)
            
        })
@@ -88,7 +85,7 @@ class SMB2ProtocolClient: FPSStreamTask {
        let smbHeader = SMB2.Header(command: .TREE_DISCONNECT, creditRequestResponse: 111, messageId: mId, treeId: treeId, sessionId: sessionId)
        let msg = SMB2.TreeDisconnect()
        let data = createSMB2Message(header: smbHeader, message: msg)
-        self.writeData(data, timeout: 0, completionHandler: { (e) in
+        self.write(data, timeout: timeout, completionHandler: { (e) in
            completionHandler?(e)
        })
        return mId
@@ -99,7 +96,7 @@ class SMB2ProtocolClient: FPSStreamTask {
        let smbHeader = SMB2.Header(command: .LOGOFF, creditRequestResponse: 0, messageId: mId, treeId: 0, sessionId: sessionId)
        let msg = SMB2.LogOff()
        let data = createSMB2Message(header: smbHeader, message: msg)
-        self.writeData(data, timeout: 0, completionHandler: { (e) in
+        self.write(data, timeout: timeout, completionHandler: { (e) in
            completionHandler?(e)
        })
        return mId
@@ -111,7 +108,7 @@ class SMB2ProtocolClient: FPSStreamTask {
 }

 // MARK: create and analyse messages
-extension SMB2ProtocolClient {
+extension FileProviderSMBTask {
    func determineSMBVersion(_ data: Data) -> Float {
        let smbverChar: Int8 = Int8(bitPattern: data.first ?? 0)
        let version = 0 - smbverChar
@@ -9,30 +9,47 @@
 import Foundation

 class SMBFileProvider: FileProvider, FileProviderMonitor {
-
-    open static var type: String = "Samba"
-    open var isPathRelative: Bool = true
+    open class var type: String { return "SMB" }
    open var baseURL: URL?
    open var currentPath: String = ""
    open var dispatch_queue: DispatchQueue
    open var operation_queue: OperationQueue
    open weak var delegate: FileProviderDelegate?
-    open let credential: URLCredential?
+    open var credential: URLCredential?
    
    public typealias FileObjectClass = FileObject
    
-    public init? (baseURL: URL, credential: URLCredential, afterInitialized: SimpleCompletionHandler) {
+    public init? (baseURL: URL, credential: URLCredential?) {
        guard baseURL.uw_scheme.lowercased() == "smb" else {
            return nil
        }
        self.baseURL = baseURL.appendingPathComponent("")
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: DispatchQueue.Attributes.concurrent)
+        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: .concurrent)
        operation_queue = OperationQueue()
        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
        
        self.credential = credential
    }
-        
+    
+    public required convenience init?(coder aDecoder: NSCoder) {
+        guard let baseURL = aDecoder.decodeObject(forKey: "baseURL") as? URL else {
+            return nil
+        }
+        self.init(baseURL: baseURL,
+                  credential: aDecoder.decodeObject(forKey: "credential") as? URLCredential)
+        self.currentPath   = aDecoder.decodeObject(forKey: "currentPath") as? String ?? ""
+    }
+    
+    open func encode(with aCoder: NSCoder) {
+        aCoder.encode(self.baseURL, forKey: "baseURL")
+        aCoder.encode(self.credential, forKey: "credential")
+        aCoder.encode(self.currentPath, forKey: "currentPath")
+    }
+    
+    public static var supportsSecureCoding: Bool {
+        return true
+    }
+    
    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObjectClass], _ error: Error?) -> Void)) {
        NotImplemented()
    }
@@ -45,6 +62,10 @@ class SMBFileProvider: FileProvider, FileProviderMonitor {
        NotImplemented()
    }
    
+    func isReachable(completionHandler: @escaping (Bool) -> Void) {
+        NotImplemented()
+    }
+    
    open weak var fileOperationDelegate: FileOperationDelegate?
    
    open func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
@@ -52,11 +73,6 @@ class SMBFileProvider: FileProvider, FileProviderMonitor {
        return nil
    }
    
-    open func create(file fileName: String, at atPath: String, contents data: Data?, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        NotImplemented()
-        return nil
-    }
-    
    open func moveItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        NotImplemented()
        return nil
@@ -92,12 +108,12 @@ class SMBFileProvider: FileProvider, FileProviderMonitor {
        return nil
    }
    
-    open func writeContents(path: String, contents data: Data, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func writeContents(path: String, contents data: Data?, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        NotImplemented()
        return nil
    }
    
-    open func searchFiles(path: String, recursive: Bool, query: String, foundItemHandler:((FileObjectClass) -> Void)?, completionHandler: @escaping ((_ files: [FileObjectClass], _ error: Error?) -> Void)) {
+    open func searchFiles(path: String, recursive: Bool, query: NSPredicate, foundItemHandler:((FileObjectClass) -> Void)?, completionHandler: @escaping ((_ files: [FileObjectClass], _ error: Error?) -> Void)) {
        NotImplemented()
    }
    
@@ -114,7 +130,7 @@ class SMBFileProvider: FileProvider, FileProviderMonitor {
    }
    
    open func copy(with zone: NSZone? = nil) -> Any {
-        let copy = SMBFileProvider(baseURL: self.baseURL!, credential: self.credential!, afterInitialized: { _ in })!
+        let copy = SMBFileProvider(baseURL: self.baseURL!, credential: self.credential!)!
        copy.currentPath = self.currentPath
        copy.delegate = self.delegate
        copy.fileOperationDelegate = self.fileOperationDelegate
@@ -123,7 +139,7 @@ class SMBFileProvider: FileProvider, FileProviderMonitor {
 }

 // MARK: basic CIFS interactivity
-public enum SMBFileProviderError: Int, Error, CustomStringConvertible {
+enum SMBFileProviderError: Int, Error, CustomStringConvertible {
    case badHeader
    case incompatibleHeader
    case incorrectParamsLength
@@ -66,32 +66,3 @@ struct SMBTime {
        return Date(timeIntervalSince1970: Double(self.time) / 10000000 - 11644473600)
    }
 }
-
-extension Data {
-    init<T>(value: T) {
-        var value = value
-        self = Data(buffer: UnsafeBufferPointer(start: &value, count: 1))
-    }
-    
-    func scanValue<T>() -> T? {
-        guard MemoryLayout<T>.size <= self.count else { return nil }
-        return self.withUnsafeBytes { $0.pointee }
-    }
-    
-    func scanValue<T>(start: Int) -> T? {
-        let length = MemoryLayout<T>.size
-        guard self.count >= start + length else { return nil }
-        return self.subdata(in: start..<start+length).withUnsafeBytes { $0.pointee }
-    }
-    
-    func scanString(start: Int = 0, length: Int, encoding: String.Encoding) -> String? {
-        guard self.count >= start + length else { return nil }
-        return String(data: self.subdata(in: start..<start+length), encoding: encoding)
-    }
-    
-    static func mapMemory<T, U>(from: T) -> U? {
-        guard MemoryLayout<T>.size >= MemoryLayout<U>.size else { return nil }
-        let data = Data(value: from)
-        return data.scanValue()
-    }
-}
@@ -106,6 +106,7 @@ extension SMB2 {
            let flags: WriteRequest.Flags
        }
        
+        // codebeat:disable[ARITY]
        init(fileId: FileId, offset: UInt64, remainingBytes: UInt32 = 0, data: Data, channel: Channel = .NONE, channelInfo: ChannelInfo? = nil, flags: WriteRequest.Flags = []) {
            var channelInfoOffset: UInt16 = 0
            var channelInfoLength: UInt16 = 0
@@ -118,6 +119,7 @@ extension SMB2 {
            self.channelInfo = channelInfo
            self.fileData = data
        }
+        // codebeat:enable[ARITY]
        
        func data() -> Data {
            var result = Data(value: self.header)
@@ -243,7 +243,7 @@ extension SMB2 {
                    if data.count < offset + 48 {
                        return nil
                    }
-                    let datestring = data.scanString(start: offset, length: 48, encoding: .utf16)
+                    let datestring = data.scanString(start: offset, length: 48, using: .utf16)
                    if let datestring = datestring, let date = dateFormatter.date(from: datestring) {
                        snapshots.append(SMBTime(date: date))
                    }
@@ -92,7 +92,7 @@ extension SMB2 {
                }
                
                let fileNameLen = Int(data.scanValue(start: offset + 8) as UInt32? ?? 0)
-                let fileName = data.scanString(start: offset + 12, length: fileNameLen, encoding: .utf16) ?? ""
+                let fileName = data.scanString(start: offset + 12, length: fileNameLen, using: .utf16) ?? ""
                result.append((action: action, fileName: fileName))
                
                offset += Int(nextOffset)
@@ -85,7 +85,7 @@ extension SMB2 {
                    return []
                }
                let headersize = MemoryLayout.size(ofValue: header)
-                let fileName = buffer.scanString(start: headersize, length: Int(header.fileNameLength), encoding: .utf16) ?? ""
+                let fileName = buffer.scanString(start: headersize, length: Int(header.fileNameLength), using: .utf16) ?? ""
                result.append((header: header, fileName: fileName))
                if header.nextEntryOffset == 0 {
                    break
@@ -216,12 +216,12 @@ extension SMB2 {
        var asAllInformation: (header: FileAllInformationHeader, name: String) {
            let header: FileAllInformationHeader = buffer.scanValue()!
            let headersize = MemoryLayout<FileAllInformationHeader>.size
-            let name = buffer.scanString(start: headersize, length: Int(header.nameLength), encoding: .utf16) ?? ""
+            let name = buffer.scanString(start: headersize, length: Int(header.nameLength), using: .utf16) ?? ""
            return (header, name)
        }
        
        var asAlternateNameInformation: String {
-            return buffer.scanString(start: 0, length: buffer.count, encoding: .utf16) ?? ""
+            return buffer.scanString(start: 0, length: buffer.count, using: .utf16) ?? ""
        }
        
        var asAttributeTagInformation: FileAttributeTagInformation {
@@ -280,14 +280,14 @@ extension SMB2 {
        var asStreamInformation: (header: FileStreamInformationHeader, name: String) {
            let header: FileStreamInformationHeader = buffer.scanValue()!
            let headersize = MemoryLayout<FileStreamInformationHeader>.size
-            let name = buffer.scanString(start: headersize, length: Int(header.streamNameLength), encoding: .utf16) ?? ""
+            let name = buffer.scanString(start: headersize, length: Int(header.streamNameLength), using: .utf16) ?? ""
            return (header, name)
        }
        
        var asFsVolumeInformation: (header: FileFsVolumeInformationHeader, name: String) {
            let header: FileFsVolumeInformationHeader = buffer.scanValue()!
            let headersize = MemoryLayout<FileFsVolumeInformationHeader>.size
-            let name = buffer.scanString(start: headersize, length: Int(header.labelLength), encoding: .utf16) ?? ""
+            let name = buffer.scanString(start: headersize, length: Int(header.labelLength), using: .utf16) ?? ""
            return (header, name)
        }
        
@@ -302,7 +302,7 @@ extension SMB2 {
        var asFsAttributeInformation: (header: FileFsAttributeInformationHeader, name: String) {
            let header: FileFsAttributeInformationHeader = buffer.scanValue()!
            let headersize = MemoryLayout<FileFsAttributeInformationHeader>.size
-            let name = buffer.scanString(start: headersize, length: Int(header.nameLength), encoding: .utf16) ?? ""
+            let name = buffer.scanString(start: headersize, length: Int(header.nameLength), using: .utf16) ?? ""
            return (header, name)
        }
        
@@ -8,12 +8,19 @@

 import Foundation

-/// Because this class uses NSURLSession, it's necessary to disable App Transport Security
-/// in case of using this class with unencrypted HTTP connection.
-
+/**
+ Allows accessing to WebDAV server files. This provider doesn't cache or save files internally, however you can
+ set `useCache` and `cache` properties to use Foundation `NSURLCache` system.
+ 
+ WebDAV system supported by many cloud services including [Box.net](https://www.box.com/home) 
+ and [Yandex disk](https://disk.yandex.com) and [ownCloud](https://owncloud.org).
+ 
+ - Important: Because this class uses `URLSession`, it's necessary to disable App Transport Security
+     in case of using this class with unencrypted HTTP connection.
+     [Read this to know how](http://iosdevtips.co/post/121756573323/ios-9-xcode-7-http-connect-server-error).
+*/
 open class WebDAVFileProvider: FileProviderBasicRemote {
-    open static let type: String = "WebDAV"
-    open let isPathRelative: Bool
+    open class var type: String { return "WebDAV" }
    open let baseURL: URL?
    open var currentPath: String
    
@@ -25,7 +32,11 @@ open class WebDAVFileProvider: FileProviderBasicRemote {
    }
    
    public weak var delegate: FileProviderDelegate?
-    open let credential: URLCredential?
+    open var credential: URLCredential? {
+        didSet {
+            sessionDelegate?.credential = credential
+        }
+    }
    open private(set) var cache: URLCache?
    public var useCache: Bool
    public var validatingCache: Bool
@@ -33,51 +44,128 @@ open class WebDAVFileProvider: FileProviderBasicRemote {
    fileprivate var _session: URLSession?
    fileprivate var sessionDelegate: SessionDelegate?
    public var session: URLSession {
-        if _session == nil {
-            self.sessionDelegate = SessionDelegate(fileProvider: self, credential: credential)
-            let queue = OperationQueue()
-            //queue.underlyingQueue = dispatch_queue
-            let config = URLSessionConfiguration.default
-            config.urlCache = cache
-            config.requestCachePolicy = .returnCacheDataElseLoad
-            _session = URLSession(configuration: config, delegate: sessionDelegate as URLSessionDownloadDelegate?, delegateQueue: queue)
+        get {
+            if _session == nil {
+                self.sessionDelegate = SessionDelegate(fileProvider: self)
+                let queue = OperationQueue()
+                //queue.underlyingQueue = dispatch_queue
+                let config = URLSessionConfiguration.default
+                config.urlCache = cache
+                config.requestCachePolicy = .returnCacheDataElseLoad
+                _session = URLSession(configuration: config, delegate: sessionDelegate as URLSessionDownloadDelegate?, delegateQueue: queue)
+                _session?.sessionDescription = UUID().uuidString
+                initEmptySessionHandler(_session!.sessionDescription!)
+            }
+            return _session!
+        }
+        
+        set {
+            assert(newValue.delegate is SessionDelegate, "session instances should have a SessionDelegate instance as delegate.")
+            _session = newValue
+            if session.sessionDescription?.isEmpty ?? true {
+                _session?.sessionDescription = UUID().uuidString
+            }
+            self.sessionDelegate = newValue.delegate as? SessionDelegate
+            initEmptySessionHandler(_session!.sessionDescription!)
        }
-        return _session!
    }
    
+    /**
+     Initializes WebDAV provider.
+     
+     - Parameters:
+       - baseURL: Location of WebDAV server.
+       - credential: An `URLCredential` object with `user` and `password`.
+       - cache: A URLCache to cache downloaded files and contents.
+    */
    public init? (baseURL: URL, credential: URLCredential?, cache: URLCache? = nil) {
        if  !["http", "https"].contains(baseURL.uw_scheme.lowercased()) {
            return nil
        }
-        self.baseURL = baseURL.appendingPathComponent("")
-        self.isPathRelative = true
+        self.baseURL = (baseURL.path.hasSuffix("/") ? baseURL : baseURL.appendingPathComponent("")).absoluteURL
        self.currentPath = ""
        self.useCache = false
        self.validatingCache = true
        self.cache = cache
        self.credential = credential
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: DispatchQueue.Attributes.concurrent)
+        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: .concurrent)
        operation_queue = OperationQueue()
        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
    }
    
-    deinit {
-        _session?.invalidateAndCancel()
+    public required convenience init?(coder aDecoder: NSCoder) {
+        guard let baseURL = aDecoder.decodeObject(forKey: "baseURL") as? URL else {
+            return nil
+        }
+        self.init(baseURL: baseURL,
+                  credential: aDecoder.decodeObject(forKey: "credential") as? URLCredential)
+        self.currentPath   = aDecoder.decodeObject(forKey: "currentPath") as? String ?? ""
+        self.useCache        = aDecoder.decodeBool(forKey: "useCache")
+        self.validatingCache = aDecoder.decodeBool(forKey: "validatingCache")
    }
    
-    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
+    open func encode(with aCoder: NSCoder) {
+        aCoder.encode(self.baseURL, forKey: "baseURL")
+        aCoder.encode(self.credential, forKey: "credential")
+        aCoder.encode(self.currentPath, forKey: "currentPath")
+        aCoder.encode(self.useCache, forKey: "useCache")
+        aCoder.encode(self.validatingCache, forKey: "validatingCache")
+    }
+    
+    public static var supportsSecureCoding: Bool {
+        return true
+    }
+    
+    open func copy(with zone: NSZone? = nil) -> Any {
+        let copy = WebDAVFileProvider(baseURL: self.baseURL!, credential: self.credential, cache: self.cache)!
+        copy.currentPath = self.currentPath
+        copy.delegate = self.delegate
+        copy.fileOperationDelegate = self.fileOperationDelegate
+        copy.useCache = self.useCache
+        copy.validatingCache = self.validatingCache
+        return copy
+    }
+    
+    deinit {
+        if let sessionuuid = _session?.sessionDescription {
+            removeSessionHandler(for: sessionuuid)
+        }
+        
+        if fileProviderCancelTasksOnInvalidating {
+            _session?.invalidateAndCancel()
+        } else {
+            _session?.finishTasksAndInvalidate()
+        }
+    }
+    
+    open func contentsOfDirectory(path: String, completionHandler: @escaping (([FileObject], Error?) -> Void)) {
+        self.contentsOfDirectory(path: path, including: [], completionHandler: completionHandler)
+    }
+    
+    /**
+     Returns an Array of `FileObject`s identifying the the directory entries via asynchronous completion handler.
+     
+     If the directory contains no entries or an error is occured, this method will return the empty array.
+     
+     - Parameter path: path to target directory. If empty, `currentPath` value will be used.
+     - Parameter including: An array which determines which file properties should be considered to fetch.
+     - Parameter completionHandler: a closure with result of directory entries or error.
+         - `contents`: An array of `FileObject` identifying the the directory entries.
+         - `error`: Error returned by system.
+     */
+    open func contentsOfDirectory(path: String, including: [URLResourceKey], completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
        let opType = FileOperationType.fetch(path: path)
        let url = self.url(of: path).appendingPathComponent("")
        var request = URLRequest(url: url)
        request.httpMethod = "PROPFIND"
        request.setValue("1", forHTTPHeaderField: "Depth")
        request.setValue("text/xml; charset=\"utf-8\"", forHTTPHeaderField: "Content-Type")
-        request.httpBody = "<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n<D:propfind xmlns:D=\"DAV:\">\n<D:allprop/></D:propfind>".data(using: .utf8)
+        request.httpBody = "<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n<D:propfind xmlns:D=\"DAV:\">\n\(WebDavFileObject.propString(including))\n</D:propfind>".data(using: .utf8)
        request.setValue(String(request.httpBody!.count), forHTTPHeaderField: "Content-Length")
        runDataTask(with: request, operationHandle: RemoteOperationHandle(operationType: opType, tasks: []), completionHandler: { (data, response, error) in
            var responseError: FileProviderWebDavError?
            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderWebDavError(code: rCode, url: url)
+                responseError = FileProviderWebDavError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8), url: url)
            }
            var fileObjects = [WebDavFileObject]()
            if let data = data {
@@ -94,17 +182,32 @@ open class WebDAVFileProvider: FileProviderBasicRemote {
    }
    
    open func attributesOfItem(path: String, completionHandler: @escaping ((_ attributes: FileObject?, _ error: Error?) -> Void)) {
+        self.attributesOfItem(path: path, including: [], completionHandler: completionHandler)
+    }
+    
+    /**
+     Returns a `FileObject` containing the attributes of the item (file, directory, symlink, etc.) at the path in question via asynchronous completion handler.
+     
+     If the directory contains no entries or an error is occured, this method will return the empty `FileObject`.
+     
+     - Parameter path: path to target directory. If empty, `currentPath` value will be used.
+     - Parameter including: An array which determines which file properties should be considered to fetch.
+     - Parameter completionHandler: a closure with result of directory entries or error.
+         - `attributes`: A `FileObject` containing the attributes of the item.
+         - `error`: Error returned by system.
+     */
+    open func attributesOfItem(path: String, including: [URLResourceKey], completionHandler: @escaping ((_ attributes: FileObject?, _ error: Error?) -> Void)) {
        let url = self.url(of: path)
        var request = URLRequest(url: url)
        request.httpMethod = "PROPFIND"
        request.setValue("1", forHTTPHeaderField: "Depth")
        request.setValue("text/xml; charset=\"utf-8\"", forHTTPHeaderField: "Content-Type")
-        request.httpBody = "<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n<D:propfind xmlns:D=\"DAV:\">\n<D:allprop/></D:propfind>".data(using: .utf8)
+        request.httpBody = "<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n<D:propfind xmlns:D=\"DAV:\">\n\(WebDavFileObject.propString(including))\n</D:propfind>".data(using: .utf8)
        request.setValue(String(request.httpBody!.count), forHTTPHeaderField: "Content-Length")
        runDataTask(with: request, completionHandler: { (data, response, error) in
            var responseError: FileProviderWebDavError?
            if let code = (response as? HTTPURLResponse)?.statusCode, code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderWebDavError(code: rCode, url: url)
+                responseError = FileProviderWebDavError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8), url: url)
            }
            if let data = data {
                let xresponse = DavResponse.parse(xmlResponse: data, baseURL: self.baseURL)
@@ -144,23 +247,68 @@ open class WebDAVFileProvider: FileProviderBasicRemote {
        })
    }
    
+    open func searchFiles(path: String, recursive: Bool, query: NSPredicate, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
+        let url = self.url(of: path)
+        var request = URLRequest(url: url)
+        request.httpMethod = "PROPFIND"
+        //request.setValue("1", forHTTPHeaderField: "Depth")
+        request.setValue("text/xml; charset=\"utf-8\"", forHTTPHeaderField: "Content-Type")
+        request.httpBody = "<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n<D:propfind xmlns:D=\"DAV:\">\n<D:allprop/></D:propfind>".data(using: .utf8)
+        runDataTask(with: request, completionHandler: { (data, response, error) in
+            // FIXME: paginating results
+            var responseError: FileProviderWebDavError?
+            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
+                responseError = FileProviderWebDavError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8), url: url)
+            }
+            if let data = data {
+                let xresponse = DavResponse.parse(xmlResponse: data, baseURL: self.baseURL)
+                var fileObjects = [WebDavFileObject]()
+                for attr in xresponse {
+                    let fileObject = WebDavFileObject(attr)
+                    if !query.evaluate(with: fileObject.mapPredicate()) {
+                        continue
+                    }
+                    
+                    fileObjects.append(fileObject)
+                    foundItemHandler?(fileObject)
+                }
+                completionHandler(fileObjects, responseError ?? error)
+                return
+            }
+            completionHandler([], responseError ?? error)
+        })
+    }
+    
+    open func isReachable(completionHandler: @escaping (Bool) -> Void) {
+        var request = URLRequest(url: baseURL!)
+        request.httpMethod = "PROPFIND"
+        request.setValue("0", forHTTPHeaderField: "Depth")
+        request.setValue("text/xml; charset=\"utf-8\"", forHTTPHeaderField: "Content-Type")
+        request.httpBody = "<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n<D:propfind xmlns:D=\"DAV:\">\n<D:prop><D:quota-available-bytes/><D:quota-used-bytes/></D:prop>\n</D:propfind>".data(using: .utf8)
+        request.setValue(String(request.httpBody!.count), forHTTPHeaderField: "Content-Length")
+        runDataTask(with: request, completionHandler: { (data, response, error) in
+            let status = (response as? HTTPURLResponse)?.statusCode ?? 400
+            completionHandler(status < 300)
+        })
+    }
+    
    open weak var fileOperationDelegate: FileOperationDelegate?
 }

 extension WebDAVFileProvider: FileProviderOperations {
    @discardableResult
-    public func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.create(path: (atPath as NSString).appendingPathComponent(folderName) + "/")
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
        }
-        let url = self.url(of: atPath).appendingPathComponent(folderName, isDirectory: true)
+        let url = self.url(of: atPath).appendingPathComponent(folderName.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) ?? folderName, isDirectory: true)
        var request = URLRequest(url: url)
        request.httpMethod = "MKCOL"
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
            var responseError: FileProviderWebDavError?
            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderWebDavError(code: rCode, url: url)
+                responseError = FileProviderWebDavError(code: rCode, path: url.relativePath, errorDescription: String(data: data ?? Data(), encoding: .utf8), url: url)
            }
            completionHandler?(responseError ?? error)
            self.delegateNotify(opType, error: responseError ?? error)
@@ -171,29 +319,7 @@ extension WebDAVFileProvider: FileProviderOperations {
    }
    
    @discardableResult
-    public func create(file fileName: String, at path: String, contents data: Data?, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.create(path: (path as NSString).appendingPathComponent(fileName))
-        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
-            return nil
-        }
-        let url = self.url(of: path).appendingPathComponent(fileName)
-        var request = URLRequest(url: url)
-        request.httpMethod = "PUT"
-        let task = session.uploadTask(with: request, from: data, completionHandler: { (data, response, error) in
-            var responseError: FileProviderWebDavError?
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderWebDavError(code: rCode, url: url)
-            }
-            completionHandler?(responseError ?? error)
-            self.delegateNotify(opType, error: responseError ?? error)
-        })
-        task.taskDescription = opType.json
-        task.resume()
-        return RemoteOperationHandle(operationType: opType, tasks: [task])
-    }
-    
-    @discardableResult
-    public func moveItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func moveItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.move(source: path, destination: toPath)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
@@ -202,7 +328,7 @@ extension WebDAVFileProvider: FileProviderOperations {
    }
    
    @discardableResult
-    public func copyItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func copyItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.copy(source: path, destination: toPath)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
@@ -211,7 +337,7 @@ extension WebDAVFileProvider: FileProviderOperations {
    }
    
    @discardableResult
-    public func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.remove(path: path)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
@@ -220,7 +346,8 @@ extension WebDAVFileProvider: FileProviderOperations {
    }
    
    func doOperation(operation opType: FileOperationType, overwrite: Bool? = nil, completionHandler: SimpleCompletionHandler) -> OperationHandle?  {
-        let sourceURL = self.url(of:opType.source!)
+        let source = opType.source!
+        let sourceURL = self.url(of: source)
        var request = URLRequest(url: sourceURL)
        if let dest = opType.destination {
            request.setValue(url(of:dest).absoluteString, forHTTPHeaderField: "Destination")
@@ -243,12 +370,13 @@ extension WebDAVFileProvider: FileProviderOperations {
            var responseError: FileProviderWebDavError?
            if let response = response as? HTTPURLResponse, let code = FileProviderHTTPErrorCode(rawValue: response.statusCode) {
                if response.statusCode >= 300  {
-                    responseError = FileProviderWebDavError(code: code, url: sourceURL)
+                    responseError = FileProviderWebDavError(code: code, path: source, errorDescription: String(data: data ?? Data(), encoding: .utf8), url: sourceURL)
                }
                if code == .multiStatus, let data = data {
                    let xresponses = DavResponse.parse(xmlResponse: data, baseURL: self.baseURL)
                    for xresponse in xresponses where (xresponse.status ?? 0) >= 300 {
-                        completionHandler?(FileProviderWebDavError(code: code, url: sourceURL))
+                        let error = FileProviderWebDavError(code: code, path: source, errorDescription: String(data: data, encoding: .utf8), url: sourceURL)
+                        completionHandler?(error)
                    }
                }
            }
@@ -264,52 +392,64 @@ extension WebDAVFileProvider: FileProviderOperations {
    }
    
    @discardableResult
-    public func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        // TODO: Make use of overwrite parameter
+    open func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        // check file is not a folder
+        guard (try? localFile.resourceValues(forKeys: [.fileResourceTypeKey]))?.fileResourceType ?? .unknown == .regular else {
+            dispatch_queue.async {
+                completionHandler?(self.throwError(localFile.path, code: URLError.fileIsDirectory))
+            }
+            return nil
+        }
+        
        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
        }
        let url = self.url(of:toPath)
        var request = URLRequest(url: url)
+        if !overwrite {
+            request.setValue("F", forHTTPHeaderField: "Overwrite")
+        }
        request.httpMethod = "PUT"
-        let task = session.uploadTask(with: request, fromFile: localFile, completionHandler: { (data, response, error) in
+        let task = session.uploadTask(with: request, fromFile: localFile)
+        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { [weak self] error in
            var responseError: FileProviderWebDavError?
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderWebDavError(code: rCode, url: url)
+            if let code = (task.response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
+                // We can't fetch server result from delegate!
+                responseError = FileProviderWebDavError(code: rCode, path: toPath, errorDescription: nil, url: url)
            }
            completionHandler?(responseError ?? error)
-            self.delegateNotify(opType, error: responseError ?? error)
-        }) 
+            self?.delegateNotify(.create(path: toPath), error: responseError ?? error)
+        }
        task.taskDescription = opType.json
        task.resume()
        return RemoteOperationHandle(operationType: opType, tasks: [task])
    }
    
    @discardableResult
-    public func copyItem(path: String, toLocalURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.copy(source: path, destination: toLocalURL.absoluteString)
+    open func copyItem(path: String, toLocalURL destURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let opType = FileOperationType.copy(source: path, destination: destURL.absoluteString)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
        }
        let url = self.url(of:path)
        let request = URLRequest(url: url)
-        let task = session.downloadTask(with: request, completionHandler: { (sourceFileURL, response, error) in
-            var responseError: FileProviderWebDavError?
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderWebDavError(code: rCode, url: url)
+        let task = session.downloadTask(with: request)
+        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = completionHandler
+        downloadCompletionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { tempURL in
+            guard let httpResponse = task.response as? HTTPURLResponse , httpResponse.statusCode < 300 else {
+                let code = FileProviderHTTPErrorCode(rawValue: (task.response as? HTTPURLResponse)?.statusCode ?? -1)
+                let serverError : FileProviderWebDavError? = code != nil ? FileProviderWebDavError(code: code!, path: path, errorDescription: code?.description, url: url) : nil
+                completionHandler?(serverError)
+                return
            }
-            if let sourceFileURL = sourceFileURL {
-                do {
-                    try FileManager.default.copyItem(at: sourceFileURL, to: toLocalURL)
-                } catch let e {
-                    completionHandler?(e)
-                    return
-                }
+            do {
+                try FileManager.default.moveItem(at: tempURL, to: destURL)
+                completionHandler?(nil)
+            } catch let e {
+                completionHandler?(e)
            }
-            completionHandler?(responseError ?? error)
-            self.delegateNotify(opType, error: responseError ?? error)
-        }) 
+        }
        task.taskDescription = opType.json
        task.resume()
        return RemoteOperationHandle(operationType: opType, tasks: [task])
@@ -318,29 +458,51 @@ extension WebDAVFileProvider: FileProviderOperations {

 extension WebDAVFileProvider: FileProviderReadWrite {
    @discardableResult
-    public func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
+    open func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
+        if length == 0 || offset < 0 {
+            dispatch_queue.async {
+                completionHandler(Data(), nil)
+            }
+            return nil
+        }
+        
        let opType = FileOperationType.fetch(path: path)
        let url = self.url(of: path)
        var request = URLRequest(url: url)
-        request.httpMethod = "GET"
        if length > 0 {
-            request.setValue("bytes=\(offset)-\(offset + length - 1)", forHTTPHeaderField: "Range")
+            request.setValue("bytes=\(offset)-\(offset + Int64(length) - 1)", forHTTPHeaderField: "Range")
        } else if offset > 0 && length < 0 {
            request.setValue("bytes=\(offset)-", forHTTPHeaderField: "Range")
        }
-        let handle = RemoteOperationHandle(operationType: opType, tasks: [])
-        runDataTask(with: request, operationHandle: handle, completionHandler: { (data, response, error) in
-            var responseError: FileProviderWebDavError?
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderWebDavError(code: rCode, url: url)
+        
+        let task = session.downloadTask(with: request)
+        let handle = RemoteOperationHandle(operationType: opType, tasks: [task])
+        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { error in
+            completionHandler(nil, error)
+        }
+        downloadCompletionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { tempURL in
+            guard let httpResponse = task.response as? HTTPURLResponse , httpResponse.statusCode < 300 else {
+                let code = FileProviderHTTPErrorCode(rawValue: (task.response as? HTTPURLResponse)?.statusCode ?? -1)
+                let serverError : FileProviderWebDavError? = code != nil ? FileProviderWebDavError(code: code!, path: path, errorDescription: code?.description, url: url) : nil
+                completionHandler(nil, serverError)
+                return
            }
-            completionHandler(data, responseError ?? error)
-        })
+            do {
+                let data = try Data(contentsOf: tempURL)
+                self.dispatch_queue.async {
+                    completionHandler(data, nil)
+                }
+            } catch let e {
+                completionHandler(nil, e)
+            }
+        }
+        task.taskDescription = opType.json
+        task.resume()
        return handle
    }
    
    @discardableResult
-    public func writeContents(path: String, contents data: Data, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func writeContents(path: String, contents data: Data?, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.modify(path: path)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
@@ -352,59 +514,22 @@ extension WebDAVFileProvider: FileProviderReadWrite {
        if !overwrite {
            request.setValue("F", forHTTPHeaderField: "Overwrite")
        }
-        let task = session.uploadTask(with: request, from: data, completionHandler: { (data, response, error) in
+        let task = session.uploadTask(with: request, from: data ?? Data())
+        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { [weak self] error in
            var responseError: FileProviderWebDavError?
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderWebDavError(code: rCode, url: self.url(of: path))
+            if let code = (task.response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
+                // We can't fetch server result from delegate!
+                responseError = FileProviderWebDavError(code: rCode, path: path, errorDescription: nil, url: url)
            }
-            defer {
-                self.delegateNotify(opType, error: responseError ?? error)
-            }
-            if let error = error {
-                completionHandler?(error)
-                return
-            }
-            if atomically {
-                self.moveItem(path: (path as NSString).appendingPathExtension("tmp")!, to: path, completionHandler: completionHandler)
-            }
-        }) 
+            completionHandler?(responseError ?? error)
+            self?.delegateNotify(opType, error: responseError ?? error)
+        }
        task.taskDescription = opType.json
        task.resume()
        return RemoteOperationHandle(operationType: opType, tasks: [task])
    }
    
-    public func searchFiles(path: String, recursive: Bool, query: String, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
-        let url = self.url(of: path)
-        var request = URLRequest(url: url)
-        request.httpMethod = "PROPFIND"
-        //request.setValue("1", forHTTPHeaderField: "Depth")
-        request.setValue("text/xml; charset=\"utf-8\"", forHTTPHeaderField: "Content-Type")
-        request.httpBody = "<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n<D:propfind xmlns:D=\"DAV:\">\n<D:allprop/></D:propfind>".data(using: .utf8)
-        runDataTask(with: request, completionHandler: { (data, response, error) in
-            // FIXME: paginating results
-            var responseError: FileProviderWebDavError?
-            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
-                responseError = FileProviderWebDavError(code: rCode, url: url)
-            }
-            if let data = data {
-                let xresponse = DavResponse.parse(xmlResponse: data, baseURL: self.baseURL)
-                var fileObjects = [WebDavFileObject]()
-                for attr in xresponse {
-                    let path = attr.href.path
-                    if !((path as NSString).lastPathComponent.contains(query)) {
-                        continue
-                    }
-                    let fileObject = WebDavFileObject(attr)
-                    fileObjects.append(fileObject)
-                    foundItemHandler?(fileObject)
-                }
-                completionHandler(fileObjects, responseError ?? error)
-                return
-            }
-            completionHandler([], responseError ?? error)
-        })
-    }
-    
+    /*
    fileprivate func registerNotifcation(path: String, eventHandler: (() -> Void)) {
        /* There is no unified api for monitoring WebDAV server content change/update
         * Microsoft Exchange uses SUBSCRIBE method, Apple uses push notification system.
@@ -412,24 +537,15 @@ extension WebDAVFileProvider: FileProviderReadWrite {
         * A messy approach is listing a directory with an interval period and compare
         * with previous results
         */
+        NotImplemented()
    }
    fileprivate func unregisterNotifcation(path: String) {
-        
-    }
+        NotImplemented()
+    }*/
    // TODO: implements methods for lock mechanism
 }

-extension WebDAVFileProvider: FileProvider {
-    open func copy(with zone: NSZone? = nil) -> Any {
-        let copy = WebDAVFileProvider(baseURL: self.baseURL!, credential: self.credential, cache: self.cache)!
-        copy.currentPath = self.currentPath
-        copy.delegate = self.delegate
-        copy.fileOperationDelegate = self.fileOperationDelegate
-        copy.useCache = self.useCache
-        copy.validatingCache = self.validatingCache
-        return copy
-    }
-}
+extension WebDAVFileProvider: FileProvider { }

 // MARK: WEBDAV XML response implementation

@@ -453,12 +569,9 @@ struct DavResponse {
    
    init? (_ node: AEXMLElement, baseURL: URL?) {
        
-        func removeSlash(_ str: String) -> String {
-            if str.hasPrefix("/") {
-                return str.substring(from: str.index(after: str.startIndex))
-            } else {
-                return str
-            }
+        func standardizePath(_ str: String) -> String {
+            let trimmedStr = str.hasPrefix("/") ? str.substring(from: str.index(after: str.startIndex)) : str
+            return trimmedStr.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) ?? str
        }
        
        // find node names with namespace
@@ -480,9 +593,14 @@ struct DavResponse {
        guard let hrefString = node[hreftag].value else { return nil }
        
        // trying to figure out relative path out of href
-        let hrefAbsolute = URL(string: hrefString, relativeTo: baseURL)?.absoluteString ?? hrefString
-        let relativePath = hrefAbsolute.replacingOccurrences(of: baseURL?.absoluteString ?? "", with: "", options: .anchored, range: nil)
-        let hrefURL = URL(string: removeSlash(relativePath), relativeTo: baseURL) ?? baseURL
+        let hrefAbsolute = URL(string: hrefString, relativeTo: baseURL)?.absoluteURL
+        let relativePath: String
+        if hrefAbsolute?.host?.replacingOccurrences(of: "www.", with: "", options: .anchored) == baseURL?.host?.replacingOccurrences(of: "www.", with: "", options: .anchored) {
+            relativePath = hrefAbsolute?.path.replacingOccurrences(of: baseURL?.absoluteURL.path ?? "", with: "", options: .anchored, range: nil) ?? hrefString
+        } else {
+            relativePath = hrefAbsolute?.absoluteString.replacingOccurrences(of: baseURL?.absoluteString ?? "", with: "", options: .anchored, range: nil) ?? hrefString
+        }
+        let hrefURL = URL(string: standardizePath(relativePath), relativeTo: baseURL) ?? baseURL
        
        guard let href = hrefURL?.standardized else { return nil }
        
@@ -520,71 +638,101 @@ struct DavResponse {
    }
    
    static func parse(xmlResponse: Data, baseURL: URL?) -> [DavResponse] {
+        guard let xml = try? AEXMLDocument(xml: xmlResponse) else { return [] }
        var result = [DavResponse]()
-        do {
-            let xml = try AEXMLDocument(xml: xmlResponse)
-            var rootnode = xml.root
-            var responsetag = "response"
-            for node in rootnode.all ?? [] where node.name.lowercased().hasSuffix("multistatus") {
-                rootnode = node
+        var rootnode = xml.root
+        var responsetag = "response"
+        for node in rootnode.all ?? [] where node.name.lowercased().hasSuffix("multistatus") {
+            rootnode = node
+        }
+        for node in rootnode.children where node.name.lowercased().hasSuffix("response") {
+            responsetag = node.name
+            break
+        }
+        for responseNode in rootnode[responsetag].all ?? [] {
+            if let davResponse = DavResponse(responseNode, baseURL: baseURL) {
+                result.append(davResponse)
            }
-            for node in rootnode.children where node.name.lowercased().hasSuffix("response") {
-                responsetag = node.name
-                break
-            }
-            for responseNode in rootnode[responsetag].all ?? [] {
-                if let davResponse = DavResponse(responseNode, baseURL: baseURL) {
-                    result.append(davResponse)
-                }
-            }
-        } catch _ {
        }
        return result
    }
 }

+/// Containts path, url and attributes of a WebDAV file or resource.
 public final class WebDavFileObject: FileObject {
    internal init(_ davResponse: DavResponse) {
        let href = davResponse.href
-        let name = davResponse.prop["displayname"] ?? (davResponse.hrefString.removingPercentEncoding! as NSString).lastPathComponent
+        let name = davResponse.prop["displayname"] ?? davResponse.href.lastPathComponent
        let relativePath = href.relativePath
        let path = relativePath.hasPrefix("/") ? relativePath : ("/" + relativePath)
        super.init(url: href, name: name, path: path)
        self.size = Int64(davResponse.prop["getcontentlength"] ?? "-1") ?? NSURLSessionTransferSizeUnknown
-        self.creationDate = resolve(dateString: davResponse.prop["creationdate"] ?? "")
-        self.modifiedDate = resolve(dateString: davResponse.prop["getlastmodified"] ?? "")
+        self.creationDate = Date(rfcString: davResponse.prop["creationdate"] ?? "")
+        self.modifiedDate = Date(rfcString: davResponse.prop["getlastmodified"] ?? "")
        self.contentType = davResponse.prop["getcontenttype"] ?? "octet/stream"
        self.isHidden = (Int(davResponse.prop["ishidden"] ?? "0") ?? 0) > 0
        self.type = self.contentType == "httpd/unix-directory" ? .directory : .regular
        self.entryTag = davResponse.prop["getetag"]
    }
    
-    /// MIME type of the file
+    /// MIME type of the file.
    open internal(set) var contentType: String {
        get {
-            return allValues["NSURLContentTypeKey"] as? String ?? ""
+            return allValues[.mimeTypeKey] as? String ?? ""
        }
        set {
-            allValues["NSURLContentTypeKey"] = newValue
+            allValues[.mimeTypeKey] = newValue
        }
    }
    
-    /// HTTP E-Tag, can be used to mark changed files
+    /// HTTP E-Tag, can be used to mark changed files.
    open internal(set) var entryTag: String? {
        get {
-            return allValues["NSURLEntryTagKey"] as? String
+            return allValues[.entryTagKey] as? String
        }
        set {
-            allValues["NSURLEntryTagKey"] = newValue
+            allValues[.entryTagKey] = newValue
        }
    }
+    
+    internal class func resourceKeyToDAVProp(_ key: URLResourceKey) -> String? {
+        switch key {
+        case URLResourceKey.fileSizeKey:
+            return "getcontentlength"
+        case URLResourceKey.creationDateKey:
+            return "creationdate"
+        case URLResourceKey.contentModificationDateKey:
+            return "getlastmodified"
+        case URLResourceKey.fileResourceTypeKey, URLResourceKey.mimeTypeKey:
+            return "getcontenttype"
+        case URLResourceKey.isHiddenKey:
+            return "ishidden"
+        case URLResourceKey.entryTagKey:
+            return "getetag"
+        default:
+            return nil
+        }
+    }
+    
+    internal class func propString(_ keys: [URLResourceKey]) -> String {
+        var propKeys = ""
+        for item in keys {
+            if let prop = WebDavFileObject.resourceKeyToDAVProp(item) {
+                propKeys += "<D:prop><D:\(prop)/></D:prop>"
+            }
+        }
+        if propKeys.isEmpty {
+            propKeys = "<D:allprop/>"
+        }
+        return propKeys
+    }
 }

-public struct FileProviderWebDavError: Error, CustomStringConvertible {
+/// Error returned by WebDAV server when trying to access or do operations on a file or folder.
+public struct FileProviderWebDavError: FileProviderHTTPError {
    public let code: FileProviderHTTPErrorCode
+    public let path: String
+    public let errorDescription: String?
+    /// URL of resource caused error.
    public let url: URL
-    
-    public var description: String {
-        return code.description
-    }
 }
Author	SHA1	Message	Date
Amir Abbas	cd465c1288	Fixes #35 (Dropbox handlers), Fixed FTP response reading length	2017-04-14 11:15:09 +04:30
Amir Abbas	a605b0cd85	Added FTP Recursive listing, Implemented ftp search - Implemented FTP full directory remove - Fixed FTP STOR bug - Implemented relativePath(of:) for FTP - Initial implementation of FTP active mode	2017-04-11 22:21:13 +04:30
Amir Abbas	bf7043de29	Fixed `relativePath(of:)` bug, made it overridable - Fixed StreamTask.taskDescription bug	2017-04-11 19:43:34 +04:30
Amir Abbas	ff5e13931f	Fixed WebDAVProvider.contents bug, refactored FTP Error	2017-04-09 14:09:03 +04:30
Amir Abbas	75af738d2e	Made SessionDelegate init public, fixed pod issue	2017-04-05 02:05:28 +04:30
Amir Abbas	f54a1253e4	Throwing error when trying to upload a directory	2017-04-05 00:24:24 +04:30
Amir Abbas	1394a92662	Add Documentation	2017-04-03 21:03:48 +04:30
Amir Abbas	dab171c755	Setting sessionDelgate credential to updated one.	2017-04-03 18:59:50 +04:30
Amir Abbas	ea5de2e2aa	Added progress for content(path:) method - Fixed issue with colliding handlers between sessions. - Sessions can be set. - SessionDelegate class is now public.	2017-04-03 18:50:13 +04:30
Amir Abbas	2253cca086	Fixed deprecated URLResourceKey items	2017-04-03 12:52:27 +04:30
Amir Abbas	e15a900ade	Renamed URLResourceKey additions to have `Key` prefix	2017-04-03 12:49:35 +04:30
Amir Abbas	5c2c56c44c	Fixed: Calling completion handler for upload task - Added including (file object properties) argument to WebDAV provider (resolves #31)	2017-04-03 12:41:11 +04:30
Amir Abbas Mousavian	ff4bbdf0de	Updated readme and podspec for FTP, minor fixes.	2017-04-01 14:56:20 +04:30
Amir Abbas Mousavian	163a218ac2	Fixed operation progress (in delegate) for all remote providers - Now also compatible with background session - added delegate notify (success, progress, failure) to FTP - added `FTPFileProvider.useAppleImplementation`, allows developer choose to use apple download task instead of custom implementation - enabling to download non-text files in FTP - implementation of `url(of:) in FTP - various fixes in error reporting - disabled closing streams in ftpQuit() due to crash	2017-04-01 01:33:56 +04:30
Amir Abbas Mousavian	81401ee36f	Added Documentation, refactors of related Date methods	2017-03-31 10:15:39 +04:30
Amir Abbas Mousavian	759ba3c7bf	Added AEXML license file	2017-03-31 00:49:08 +04:30
Amir Abbas Mousavian	f5c8f6308b	FileProviderStreamTask (URLSessionStreakTask replica) is now public - closing streams after ftpQuit() executed. - added ability to add FTP Active Mode.	2017-03-30 23:49:28 +04:30
Amir Abbas Mousavian	4dbb0adb18	FTP better error handling	2017-03-30 13:16:03 +04:30
Amir Abbas Mousavian	bf62d585fd	implemented FTP copy fallback, FTPS manual auth	2017-03-30 10:41:14 +04:30
Amir Abbas Mousavian	f21f658874	Deprecated create(file:) method, replaced by writeContents() - RemoteOperationHandle now retains task - FTP provider returns correct operation handle task	2017-03-29 23:03:04 +04:30
Amir Abbas	e6eba3d198	Fixed macOS and tvOS build	2017-03-29 10:13:47 +04:30
Amir Abbas	6959a14dc1	Fixed compiler error, closing streams in FTP provider	2017-03-29 09:29:22 +04:30
Amir Abbas	29a9e0fb82	Initial implementation of FTP - ftp copy and search is not implemented	2017-03-29 04:17:03 +04:30
Amir Abbas Mousavian	c7b4e1f124	Ensure baseURL is absolute, fixed warnings for Swift 3.1	2017-03-28 19:25:41 +04:30
Amir Abbas Mousavian	99a433a0fc	Credential is open to set anytime	2017-03-26 15:54:55 +04:30
Amir Abbas Mousavian	4023fbc62e	Fixed: WebDAV file listing omit files contains space in name	2017-03-26 02:03:43 +04:30
Amir Abbas Mousavian	1045901d7c	Added NSCoding support - Better relative path handling in WebDAV - obsolete deprecated methods	2017-03-25 19:19:49 +04:30
Amir Abbas	528d5eebc3	Fixed relativePath(of:) crash	2017-03-18 15:58:44 +03:30
Amir Abbas	079f8f4b77	Refactored methods to extensions	2017-03-17 15:52:58 +03:30
Amir Abbas	e12f386a9d	Refactored DispatchTime, better ExposureTime calculation	2017-03-11 03:02:02 +03:30
Amir Abbas	38e217bc19	Better LocalFileObject initialization with empty path	2017-03-09 17:34:00 +03:30
Amir Abbas	0b41abd4ef	Optimized PDF thumbnail/meta handling - Fixed ISO speed and GPS Area image meta - Fixed Dropbox `name ! BEGINSWiTH %` search query	2017-03-01 13:28:44 +03:30
Amir Abbas	aa781adeb2	Fixed searchFiles() from string, fixing “BEGINSWITH” typo	2017-02-24 16:53:59 +03:30
Amir Abbas	d61e51ba1c	Fixes #29 (WebDAV authentication), minor lints/optimiziations	2017-02-24 16:24:34 +03:30
Amir Abbas	cdff7db32e	Fixed OneDriveProvider bugs - fixed and enhanced searching files in Dropbox	2017-02-21 00:48:59 +03:30
Amir Abbas	9533a0e3c9	Removed redundant `isPathRelative` property. Now is always true. - Note: Check documentation to workaround - Improvement: Disabling `LocalFileProviderMonitor` while handler is running	2017-02-20 00:14:55 +03:30
Amir Abbas	194673b3b6	Added NSPredicate to searchFiles method - public functions became open, now is overridable - fixed urlCache documentation	2017-02-19 13:34:55 +03:30
Amir Abbas	194c8a41aa	Fixed readme	2017-02-18 09:08:55 +03:30
Amir Abbas Mousavian	c290377433	Updated Readme, travis.yml	2017-02-16 20:56:24 +03:30
Amir Abbas Mousavian	330a22c45d	Completed Documentation, fixed a small bug.	2017-02-16 13:00:50 +03:30
Amir Abbas	e899804e28	Added isReachable method to test connectivity - Fixed Cloud provider bug when moving/deleting evicted file	2017-02-14 22:58:07 +03:30
Amir Abbas	489a9a16d0	Updated documentation, fixed Cloud provider paths bugs	2017-02-14 12:24:06 +03:30
Amir Abbas	93359d5173	Made FileProviders equatable	2017-02-13 16:45:34 +03:30
Amir Abbas	12ff3a410d	Fixed critical bug in LocalFileObject when decoding path	2017-02-13 16:31:29 +03:30
Amir Abbas	a7de09362b	Equatable FileObject, async completion handler in cloud provider	2017-02-13 12:06:09 +03:30
Amir Abbas	b1fe37cf2a	Updated Readme, fixed several bugs - non-locking snapshot of file while uploading to iCloud - fixed: `CloudFIleProvider.doOperation()` couldn’t handle local urls - fixed: FileProvider.type didn’t work correctly	2017-02-12 22:45:30 +03:30
Amir Abbas	bd59eacee2	Fixed bugs in providers and LocalFileObject initializing	2017-02-12 03:07:40 +03:30
Amir Abbas	42579be371	Added FileProviderHTTPError protocol - All errors from local provider is now from Cocoa error domain. No URL domain anymore. - All errors from WebDAV/OneDrive/Dropbox conform to FileProviderHTTPError	2017-02-11 18:05:21 +03:30
Amir Abbas	edd4914ca7	Linting, fixed travis wrong device	2017-02-11 06:08:17 +03:30
Amir Abbas	bd3e1bd74f	Fixed typos in travis.yml	2017-02-10 02:57:15 +03:30
Amir Abbas	371c481482	Fixed project name typo in travis.yml	2017-02-09 15:02:39 +03:30
Amir Abbas	dea1d01bf3	Made travis.yml more generic	2017-02-09 14:46:29 +03:30
Amir Abbas	ae4cd1dff3	Fixed undo manager bugs - Fixed contents of file with offset method bugs - Improved `LocalFileProvider.copy()` implementation	2017-02-09 03:02:21 +03:30
Amir Abbas	72520973e9	Changed FileObject.allValues key type to URLResourceKey - LocalFileProvider.storageProperties method now uses url resource values	2017-02-08 07:30:41 +03:30
Amir Abbas	63016285af	Added UndoManager support to Local provider - Refactored Local provider operations into one function	2017-02-08 04:54:18 +03:30
Amir Abbas	3245c9df03	Updated travis.yml	2017-02-07 21:59:17 +03:30
Amir Abbas	ee1fa89747	Updated travis.yml	2017-02-07 12:07:59 +03:30
Amir Abbas	4a6b25deac	Updated travis.yml	2017-02-07 09:48:12 +03:30
Amir Abbas	2423cbd0f6	Updated travis.yml	2017-02-07 02:55:22 +03:30
Amir Abbas	480099ca8a	Updated travis.yml	2017-02-06 19:41:57 +03:30
Amir Abbas	755bf6bf84	Updated travis.yaml	2017-02-06 19:38:14 +03:30
Amir Abbas	525825ff5d	Fixed Cloud provider listing (RunLoop) bug - Added ubiquity scope to Cloud provider - Renamed `temporaryLink` to `publicLink` - Added deprecated renaming guide	2017-02-06 18:03:58 +03:30
Amir Abbas Mousavian	a35384dc31	Refactoring: reducing complexity of properties methods	2017-02-03 23:15:23 +03:30
Amir Abbas Mousavian	0c558fdbb4	Updated version	2017-02-03 18:33:25 +03:30
Amir Abbas Mousavian	e30861ad18	Added publicLink method to OneDrive - Added more Documentation, specially initializer - Added option to conserve sessions after provider deinit to finish tasks - Dropbox and OneDrive init are not bailable anymore - Updated AEXML	2017-02-03 18:29:34 +03:30
Amir Abbas Mousavian	538e9bb42d	Updated provider descriptions	2017-02-02 19:32:28 +03:30
Amir Abbas Mousavian	ef2d69c54c	Updated supported providers order	2017-02-02 19:26:26 +03:30
Amir Abbas Mousavian	9f210ef356	Updated readme link to cocoa pods docs	2017-02-02 13:32:58 +03:30
Amir Abbas Mousavian	5a7dfa1039	Merge commit 'b84e6ea7abbec6f9a83144d2dcd6744b568d682f' * commit 'b84e6ea7abbec6f9a83144d2dcd6744b568d682f': Updated Date	2017-02-02 13:28:08 +03:30
Amir Abbas Mousavian	be7a370a42	Added Documentation, get contents handling in Local provider optimized - Changed default thumbnail dimension to 64x64 in `LocalFileProvider`	2017-02-02 13:25:40 +03:30
Amir Abbas Mousavian	b84e6ea7ab	Updated Date	2017-02-02 01:03:48 +03:30
Amir Abbas Mousavian	82b1d2c450	Added new badges	2017-02-01 22:18:20 +03:30