Added NSPredicate to searchFiles method

- public functions became open, now is overridable - fixed urlCache documentation
Fixed readme
2017-02-19 13:34:55 +03:30 · 2017-02-18 09:08:55 +03:30 · 2017-02-16 20:56:24 +03:30 · 2017-02-16 13:00:50 +03:30 · 2017-02-14 22:58:07 +03:30 · 2017-02-14 12:24:06 +03:30
28 changed files with 3303 additions and 1064 deletions
@@ -1,27 +1,80 @@
 language: objective-c
-osx_image: xcode8
-xcode_project: FileProvider.xcodeproj
+osx_image: xcode8.2
+xcode_project: $PROJECTNAME.xcodeproj
 env:
  global: 
-    - FRAMEWORK_NAME=FileProvider.framework
+  - PROJECT="$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:
+    - 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-  - brew outdated carthage || brew upgrade carthage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 FileProvider.xcodeproj -scheme "FileProvider OSX" -sdk macosx | xcpretty
-  - xcodebuild -project FileProvider.xcodeproj -scheme "FileProvider iOS" -sdk iphonesimulator ONLY_ACTIVE_ARCH=NO | xcpretty
-  - xcodebuild -project FileProvider.xcodeproj -scheme "FileProvider tvOS" -sdk appletvsimulator ONLY_ACTIVE_ARCH=NO | xcpretty
-  - pod lib lint --quick
+
+  # 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;
+    fi
+
 after_success:
-  - bash <(curl -s https://codecov.io/bash)
+  # Run `pod trunk push` if specified
+  - if [ $POD == "YES" ] && [ -n "$TRAVIS_TAG" ]; then
+      pod trunk push;
+    fi
+
+#   - bash <(curl -s https://codecov.io/bash)
 before_deploy:
-  - carthage build --no-skip-current
-  - carthage archive FileProvider
+  - 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 $PROJECTNAME;
+    fi
+
 deploy:
-  file: FileProvider.framework.zip
+  provider: releases
+  api_key: "$GITHUBTOKEN"
+  file: $FRAMEWORK_NAME.zip
  skip_cleanup: true
  on:
-    tags: true
+    repo: amosavian/$PROJECTNAME
+    tags: true
+    condition: "$CARTHAGEDEPLOY = YES"
@@ -16,7 +16,7 @@ Pod::Spec.new do |s|
  #

  s.name         = "FileProvider"
-  s.version      = "0.10.1"
+  s.version      = "0.14.0"
  s.summary      = "FileManager replacement for Local and Remote (WebDAV/Dropbox/OneDrive/SMB2) files on iOS and macOS."

  # This description is used to generate tags and improve search results.
@@ -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 */; };
+		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 */; };
 		794C21FE1D58912A00EC49B8 /* DropboxHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 794C21FD1D58912A00EC49B8 /* DropboxHelper.swift */; };
 		794C21FF1D58912A00EC49B8 /* DropboxHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 794C21FD1D58912A00EC49B8 /* DropboxHelper.swift */; };
 		794C22001D58912A00EC49B8 /* DropboxHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 794C21FD1D58912A00EC49B8 /* DropboxHelper.swift */; };
@@ -127,6 +130,7 @@
 		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>"; };
+		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>"; };
@@ -158,14 +162,11 @@
 		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; };
@@ -217,14 +218,11 @@
 				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 */,
@@ -286,6 +284,7 @@
 				79F5745A1DFDB10A00179ABF /* FileObject.swift */,
 				799396961D48C02300086753 /* LocalFileProvider.swift */,
 				792572401DF23BDA006A1526 /* LocalHelper.swift */,
+				79480FF51E3ABDD0007E7275 /* CloudFileProvider.swift */,
 				79BD638B1E2CC2300035128C /* ExtendedLocalFileProvider.swift */,
 				7902C0851D61B56D00564440 /* RemoteSession.swift */,
 				799396931D48C02300086753 /* DropboxFileProvider.swift */,
@@ -480,6 +479,7 @@
 				799396D41D48C02300086753 /* SMB2Tree.swift in Sources */,
 				7924B1A21D89DAE000589DB7 /* Options.swift in Sources */,
 				792572411DF23BDA006A1526 /* LocalHelper.swift in Sources */,
+				79480FF61E3ABDD0007E7275 /* CloudFileProvider.swift in Sources */,
 				79F5745B1DFDB10B00179ABF /* FileObject.swift in Sources */,
 				79BD63C51E2D17880035128C /* OneDriveFileProvide.swift in Sources */,
 				7924B1991D89DAE000589DB7 /* Element.swift in Sources */,
@@ -519,6 +519,7 @@
 				799396D51D48C02300086753 /* SMB2Tree.swift in Sources */,
 				7924B1A31D89DAE000589DB7 /* Options.swift in Sources */,
 				792572421DF23BDA006A1526 /* LocalHelper.swift in Sources */,
+				79480FF71E3ABDD0007E7275 /* CloudFileProvider.swift in Sources */,
 				79F5745C1DFDB10B00179ABF /* FileObject.swift in Sources */,
 				79BD63C61E2D17880035128C /* OneDriveFileProvide.swift in Sources */,
 				7924B1B01D89F7DE00589DB7 /* FPSStreamTask.swift in Sources */,
@@ -558,6 +559,7 @@
 				799396D61D48C02300086753 /* SMB2Tree.swift in Sources */,
 				7924B1A41D89DAE000589DB7 /* Options.swift in Sources */,
 				792572431DF23BDA006A1526 /* LocalHelper.swift in Sources */,
+				79480FF81E3ABDD0007E7275 /* CloudFileProvider.swift in Sources */,
 				79F5745D1DFDB10B00179ABF /* FileObject.swift in Sources */,
 				79BD63C71E2D17880035128C /* OneDriveFileProvide.swift in Sources */,
 				7924B1B11D89F7DF00589DB7 /* FPSStreamTask.swift in Sources */,
@@ -595,7 +597,7 @@
 		799396601D48B7BF00086753 /* Debug */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
-				BUNDLE_VERSION_STRING = 0.10.1;
+				BUNDLE_VERSION_STRING = 0.14.0;
 				CLANG_WARN_BOOL_CONVERSION = YES;
 				CLANG_WARN_CONSTANT_CONVERSION = YES;
 				CLANG_WARN_EMPTY_BODY = YES;
@@ -625,7 +627,7 @@
 		799396611D48B7BF00086753 /* Release */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
-				BUNDLE_VERSION_STRING = 0.10.1;
+				BUNDLE_VERSION_STRING = 0.14.0;
 				CLANG_WARN_BOOL_CONVERSION = YES;
 				CLANG_WARN_CONSTANT_CONVERSION = YES;
 				CLANG_WARN_EMPTY_BODY = 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
@@ -1,40 +1,48 @@
-# 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][platform-image]](#)
 [![License][license-image]][license-url]
-[![Platform](https://img.shields.io/badge/Platform-iOS%2C%20macOS%2C%20tvOS-lightgray.svg)]()
+
+[![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]
-[![CocoaPods Compatible](https://img.shields.io/cocoapods/v/FileProvider.svg)](https://cocoapods.org/pods/FileProvider)
-[![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)
-[![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage) 
+[![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.

 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.
-
 ## Features

 - [x] **LocalFileProvider** a wrapper around `FileManager` with some additions like searching and reading a portion of file.
+- [x] **CloudFileProvider** A wrapper around app's ubiquitous container to iCloud Drive in iOS 8+ API.
 - [x] **WebDAVFileProvider** WebDAV protocol is defacto file transmission standard, replaced FTP.
- [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 servers. For now it has limitation in uploading files up to 100MB.
- [ ] **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. I implemented data types and some basic functions but *main interface is not implemented yet!* SMB1/CIFS is depericated and very tricky to be implemented
+- [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 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.
 - [ ] **FTPFileProvider** while deprecated in 1990s, it's still in use on some Web hosts.
- [ ] **AmazonS3FileProvider** 

 ## Requirements

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

@@ -59,7 +67,7 @@ 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, minorVersion: 12)
 ```

 ### Manually
@@ -85,7 +93,7 @@ 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

@@ -97,18 +105,31 @@ For LocalFileProvider if you want to deal with `Documents` folder

 ```	swift
 let documentsProvider = LocalFileProvider()
-```

-is equal to:
+// Equals with:
+let documentsProvider = LocalFileProvider(directory: .documentDirectory, domainMask: = .userDomainMask)

-```	swift
-let documentPath = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true);
-let documentsURL = URL(fileURLWithPath: documentPath);
+// Equals with:
+let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
 let documentsProvider = LocalFileProvider(baseURL: documentsURL)
 ```

+Also for using group shared container:
+
+```swift
+let documentsProvider = LocalFileProvider(sharedContainerId: "group.yourcompany.appContainer")
+// 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 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)
+```
+
+
 For remote file providers authentication may be necessary:

 ```	swift
@@ -122,7 +143,7 @@ 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

@@ -137,7 +158,7 @@ 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).")
@@ -148,7 +169,7 @@ 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.")
@@ -159,7 +180,7 @@ 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.")
@@ -241,7 +262,13 @@ 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:
@@ -306,20 +333,62 @@ let data = "What's up Newyork!".data(encoding: .utf8)
 documentsProvider.writeContents(path: "old.txt", content: data, atomically: true, completionHandler: nil)
 ```

+### 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
+### 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 
 }
 	
@@ -342,7 +411,7 @@ 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
        }
@@ -354,7 +423,7 @@ 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
@@ -370,6 +439,12 @@ 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 to do:
+
+- [ ] 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)
@@ -379,17 +454,28 @@ 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-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
+[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
+[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>
@@ -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 {
@@ -0,0 +1,804 @@
+//
+//  CloudFileProvider.swift
+//  FileProvider
+//
+//  Created by Amir Abbas Mousavian.
+//  Copyright © 2017 Mousavian. Distributed under MIT license.
+//
+
+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" }
+    
+    /// 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
+        }
+    }
+    
+    /// The fully-qualified container identifier for an iCloud container directory.
+    open fileprivate(set) var containerId: String?
+    
+    /// 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
+        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.\(type(of: self).type)", attributes: .concurrent)
+        operation_queue = OperationQueue()
+        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
+        
+        fileManager.url(forUbiquityContainerIdentifier: containerId)
+        opFileManager.url(forUbiquityContainerIdentifier: containerId)
+        
+        try? fileManager.createDirectory(at: baseURL, withIntermediateDirectories: true)
+    }
+    
+    /**
+     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.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
+                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, url.deletingLastPathComponent().path.trimmingCharacters(in: pathTrimSet) == pathURL.path.trimmingCharacters(in: pathTrimSet) else {
+                        continue
+                    }
+                    
+                    if let file = self.mapFileObject(attributes: attribs) {
+                        contents.append(file)
+                    }
+                }
+                
+                query.stop()
+                self.dispatch_queue.async {
+                    completionHandler(contents, nil)
+                }
+                
+            })
+            DispatchQueue.main.async {
+                if !query.start() {
+                    self.dispatch_queue.async {
+                        completionHandler([], self.throwError(path, code: CocoaError.fileReadNoPermission))
+                    }
+                }
+            }
+        }
+    }
+    
+    /// 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.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
+                defer {
+                    query.stop()
+                    NotificationCenter.default.removeObserver(finishObserver!)
+                }
+                
+                query.disableUpdates()
+                
+                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)
+                    self.dispatch_queue.async {
+                        completionHandler(nil, error)
+                    }
+                    return
+                }
+                
+                if let file = self.mapFileObject(attributes: attribs) {
+                    self.dispatch_queue.async {
+                        completionHandler(file, nil)
+                    }
+                } else {
+                    let noFileError = self.throwError(path, code: CocoaError.fileNoSuchFile)
+                    self.dispatch_queue.async {
+                        completionHandler(nil, noFileError)
+                    }
+                }
+            })
+            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[0])
+                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? {
+        guard let r = super.create(folder: folderName, at: atPath, completionHandler: completionHandler) else { return nil }
+        return CloudOperationHandle(operationType: r.operationType, baseURL: self.baseURL)
+    }
+    
+    /**
+     Creates an new file with data passed to method asynchronously.
+     Returns error via completionHandler if file is already exists.
+     
+     - Parameters:
+       - file: New file name with extension separated by period.
+       - at: Parent path of new file.
+       - data: Data of new files. Pass nil or `Data()` to create empty file.
+       - 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(file fileName: String, at atPath: String, contents data: Data?, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        guard let r = super.create(file: fileName, at: atPath, contents: data, 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? {
+        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? {
+        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? {
+        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
+        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
+        operation_queue.addOperation {
+            let tempFolder: URL
+            if #available(iOS 10.0, macOS 10.12, tvOS 10.0, *) {
+                tempFolder = FileManager.default.temporaryDirectory
+            } else {
+                tempFolder = URL(fileURLWithPath: NSTemporaryDirectory())
+            }
+            let tmpFile = tempFolder.appendingPathComponent(UUID().uuidString)
+            
+            do {
+                try self.opFileManager.copyItem(at: localFile, to: tmpFile)
+                let toUrl = self.url(of: toPath)
+                try self.opFileManager.setUbiquitous(true, itemAt: tmpFile, destinationURL: toUrl)
+                completionHandler?(nil)
+                DispatchQueue.main.async(execute: {
+                    self.delegate?.fileproviderSucceed(self, operation: opType)
+                })
+            } catch let e {
+                if self.opFileManager.fileExists(atPath: tmpFile.path) {
+                    try? self.opFileManager.removeItem(at: tmpFile)
+                }
+                completionHandler?(e)
+                DispatchQueue.main.async(execute: {
+                    self.delegate?.fileproviderFailed(self, operation: opType)
+                })
+            }
+        }
+        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)
+        
+        do {
+            try self.opFileManager.startDownloadingUbiquitousItem(at: self.url(of: path))
+        } catch let e {
+            completionHandler?(e)
+            DispatchQueue.main.async(execute: {
+                self.delegate?.fileproviderFailed(self, operation: opType)
+            })
+            return nil
+        }
+        
+        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? {
+        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? {
+        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? {
+        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)
+    }
+    
+    fileprivate var monitors = [String: (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.valueListAttributes = []
+        query.searchScopes = [self.scope.rawValue]
+        
+        let updateObserver = NotificationCenter.default.addObserver(forName: .NSMetadataQueryDidUpdate, object: query, queue: nil, using: { (notification) in
+            
+            query.disableUpdates()
+            
+            eventHandler()
+            
+            query.enableUpdates()
+        })
+        
+        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) {
+        guard let (query, observer) = monitors[path] else {
+            return
+        }
+        query.disableUpdates()
+        query.stop()
+        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[path] != 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
+    }
+    
+    fileprivate func mapFileObject(attributes attribs: [String: Any]) -> FileObject? {
+        guard let url = (attribs[NSMetadataItemURLKey] as? URL)?.standardizedFileURL, let name = attribs[NSMetadataItemFSNameKey] as? String else {
+            return nil
+        }
+        
+        let path = self.relativePathOf(url: url)
+        let rpath = path.hasPrefix("/") ? path.substring(from: path.index(after: path.startIndex)) : path
+        let relativeUrl = URL(string: rpath, relativeTo: self.baseURL)
+        let file = FileObject(url: relativeUrl ?? url, name: name, path: path)
+        
+        file.size = (attribs[NSMetadataItemFSSizeKey] as? NSNumber)?.int64Value ?? -1
+        file.creationDate = attribs[NSMetadataItemFSCreationDateKey] as? Date
+        file.modifiedDate = attribs[NSMetadataItemFSContentChangeDateKey] as? Date
+        let isFolder = (attribs[NSMetadataItemContentTypeTreeKey] as? [String])?.contains("public.folder") ?? false
+        let isSymbolic = (attribs[NSMetadataItemContentTypeTreeKey] as? [String])?.contains("public.symlink") ?? false
+        file.type = isFolder ? .directory : (isSymbolic ? .symbolicLink : .regular)
+        
+        return file
+    }
+    
+    /// 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 {
+                try self.opFileManager.evictUbiquitousItem(at: self.url(of: path))
+                completionHandler?(nil)
+            } catch let e {
+                completionHandler?(e)
+            }
+        }
+    }
+    
+    /**
+     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)
+                self.dispatch_queue.async {
+                    completionHandler(url, nil, expiration as Date?, nil)
+                }
+            } catch let 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
+        }
+    }
+}
+
+open class CloudOperationHandle: OperationHandle {
+    public let baseURL: URL?
+    public let operationType: FileOperationType
+    
+    init (operationType: FileOperationType, baseURL: URL?) {
+        self.baseURL = baseURL
+        self.operationType = operationType
+    }
+    
+    private var sourceURL: URL? {
+        guard let source = operationType.source, let baseURL = baseURL else { return nil }
+        return source.hasPrefix("file://") ? URL(fileURLWithPath: source) : baseURL.appendingPathComponent(source)
+    }
+    
+    private var destURL: URL? {
+        guard let dest = operationType.destination, let baseURL = baseURL else { return nil }
+        return dest.hasPrefix("file://") ? URL(fileURLWithPath: dest) : baseURL.appendingPathComponent(dest)
+    }
+    
+    open var bytesSoFar: 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 0 }
+        let downloaded = item.value(forAttribute: NSMetadataUbiquitousItemPercentDownloadedKey) as? Double ?? 0
+        let uploaded = item.value(forAttribute: NSMetadataUbiquitousItemPercentUploadedKey) as? Double ?? 0
+        guard let size = item.value(forAttribute: NSMetadataItemFSSizeKey) as? Int64 else { return -1 }
+        if (downloaded == 0 || downloaded == 100) && (uploaded > 0 && uploaded < 100) {
+            return Int64(uploaded * (Double(size) / 100))
+        } else if (uploaded == 0 || uploaded == 100) && (downloaded > 0 && downloaded < 100) {
+            return Int64(downloaded * (Double(size) / 100))
+        } else if uploaded == 100 || downloaded == 100 {
+            return size
+        }
+        return 0
+    }
+    
+    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 }
+        return item.value(forAttribute: NSMetadataItemFSSizeKey) as? Int64 ?? -1
+    }
+    
+    open var inProgress: Bool {
+        guard let url = destURL ?? sourceURL, let item = CloudOperationHandle.getMetadataItem(url: url) else { return false }
+        let downloadStatus = item.value(forAttribute: NSMetadataUbiquitousItemDownloadingStatusKey) as? String ?? NSMetadataUbiquitousItemDownloadingStatusNotDownloaded
+        let isUploading = item.value(forAttribute: NSMetadataUbiquitousItemIsUploadingKey) as? Bool ?? false
+        return downloadStatus == NSMetadataUbiquitousItemDownloadingStatusCurrent || isUploading
+    }
+    
+    /// 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, 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 {
+                query.stop()
+                group.leave()
+                NotificationCenter.default.removeObserver(finishObserver!)
+            }
+            
+            if query.resultCount > 0 {
+                item = query.result(at: 0) as? NSMetadataItem
+            }
+            
+            query.disableUpdates()
+            
+        })
+        
+        DispatchQueue.main.async {
+            query.start()
+        }
+        _ = group.wait(timeout: DispatchTime.now() + 30)
+        return item
+    }
+}
@@ -10,54 +10,83 @@
 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 DropboxFileProvider: NSObject,  FileProviderBasicRemote {
-    open static let type: String = "DropBox"
-    open let isPathRelative: Bool = true
+/**
+ 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 class var type: String { return "DropBox" }
+    open let isPathRelative: Bool
    open let baseURL: URL?
-    open var currentPath: String = ""
+    open var currentPath: String
    
-    open let apiURL = URL(string: "https://api.dropboxapi.com/2/")!
-    open let contentURL = URL(string: "https://content.dropboxapi.com/2")!
+    /// 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 {
+    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 = false
-    public var validatingCache: Bool = true
+    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)
+            _session = URLSession(configuration: config, delegate: sessionDelegate as URLSessionDelegate?, delegateQueue: self.operation_queue)
        }
        return _session!
    }
    
-    public init? (credential: URLCredential?, cache: URLCache? = nil) {
+    /**
+     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
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(DropboxFileProvider.type)", attributes: DispatchQueue.Attributes.concurrent)
-        //let url = baseURL.uw_absoluteString
-        self.credential = credential
+        self.isPathRelative = true
+        self.currentPath = ""
+        self.useCache = false
+        self.validatingCache = true
        self.cache = cache
+        self.credential = credential
+        
+        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: .concurrent)
+        operation_queue = OperationQueue()
+        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
+
    }
    
    deinit {
-        _session?.invalidateAndCancel()
+        if fileProviderCancelTasksOnInvalidating {
+            _session?.invalidateAndCancel()
+        } else {
+            _session?.finishTasksAndInvalidate()
+        }
    }
    
    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
@@ -72,19 +101,19 @@ open class DropboxFileProvider: NSObject,  FileProviderBasicRemote {
        request.httpMethod = "POST"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
-        let requestDictionary = ["path": correctPath(path)! as NSString]
+        let requestDictionary: [String: AnyObject] = ["path": correctPath(path)! as NSString]
        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
        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 = self.mapToFileObject(json) {
+                serverError = 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) {
                    fileObject = file
                }
            }
-            completionHandler(fileObject, dbError ?? error)
+            completionHandler(fileObject, serverError ?? error)
        }) 
        task.resume()
    }
@@ -106,31 +135,48 @@ open class DropboxFileProvider: NSObject,  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]()
+        guard let queryStr = self.findNameQuery(query, key: "name") as? String else { return }
+        search(path, query: queryStr, foundItem: { (file) in
+            if query.evaluate(with: file.mapPredicate()) {
+                foundFiles.append(file)
+                foundItemHandler?(file)
+            }
+        }, completionHandler: { (error) in
+            completionHandler(foundFiles, 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? {
+    open 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)
    }
    
@@ -166,19 +212,19 @@ extension DropboxFileProvider: FileProviderOperations {
        }
        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
        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? {
        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
@@ -186,7 +232,7 @@ 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
@@ -195,15 +241,15 @@ extension DropboxFileProvider: FileProviderOperations {
        var request = URLRequest(url: url)
        request.httpMethod = "GET"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        let requestDictionary = ["path": path]
-        let requestJson = dictionaryToJSON(requestDictionary as [String : AnyObject]) ?? ""
+        let requestDictionary: [String: AnyObject] = ["path": path as NSString]
+        let requestJson = dictionaryToJSON(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 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 ?? error)
                return
            }
            do {
@@ -220,26 +266,33 @@ 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)", forHTTPHeaderField: "Range")
+            request.setValue("bytes=\(offset)-\(offset + length - 1)", forHTTPHeaderField: "Range")
        } else if offset > 0 && length < 0 {
            request.setValue("bytes=\(offset)-", forHTTPHeaderField: "Range")
        }
-        let requestDictionary = ["path": correctPath(path)! as NSString]
-        request.setValue(dictionaryToJSON(requestDictionary as [String : AnyObject]), forHTTPHeaderField: "Dropbox-API-Arg")
+        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?
+            var serverError: 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))
+                serverError = FileProviderDropboxError(code: code, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8))
            }
-            let filedata = dbError ?? error == nil ? data : nil
-            completionHandler(filedata, dbError ?? error)
+            let filedata = serverError ?? error == nil ? data : nil
+            completionHandler(filedata, serverError ?? error)
        })
        task.taskDescription = opType.json
        task.resume()
@@ -255,16 +308,7 @@ extension DropboxFileProvider: FileProviderReadWrite {
        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)
-        })
-    }
-    
+    /*
    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
@@ -277,70 +321,143 @@ 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 {
+    /// *DEPRECATED:* Use `publicLink(to:, completionHandler: (URL?, DropboxFileObject?, Date?,  Error?))` function instead.
+    @available(*, deprecated, renamed: "publicLink(to:completionHandler:)", message: "Use publicLink(to:, completionHandler: (URL?, DropboxFileObject?, Date?,  Error?)) function instead.")
    open func temporaryLink(to path: String, completionHandler: @escaping ((_ link: URL?, _ attribute: DropboxFileObject?, _ error: Error?) -> Void)) {
+        self.publicLink(to: path) { (url, file, _, error) in
+            completionHandler(url, file, error)
+        }
+    }
+    
+    /// *DEPRECATED:* Use `publicLink(to:, completionHandler: (URL?, DropboxFileObject?, Date?,  Error?))` function instead.
+    @available(*, deprecated, renamed: "publicLink(to:completionHandler:)", message: "Use publicLink(to:, completionHandler: (URL?, DropboxFileObject?, Date?,  Error?)) function instead.")
+    open func temporaryLink(to path: String, completionHandler: @escaping ((_ link: URL?, _ attribute: DropboxFileObject?, _ expiration: Date?, _ error: Error?) -> Void)) {
+        self.publicLink(to: path) { (url, file, expiration, error) in
+            completionHandler(url, file, expiration, error)
+        }
+    }
+    
+    /**
+     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 = ["path": correctPath(path)! as NSString]
+        let requestDictionary: [String: AnyObject] = ["path": correctPath(path)! as NSString]
        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
        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
+                serverError = 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) {
                    if let linkStr = json["link"] as? String {
                        link = URL(string: linkStr)
                    }
                    if let attribDic = json["metadata"] as? [String: AnyObject] {
-                        fileObject = self.mapToFileObject(attribDic)
+                        fileObject = DropboxFileObject(json: attribDic)
                    }
                }
            }
-            completionHandler(link, fileObject, dbError ?? error)
+            
+            let expiration: Date? = link != nil ? Date(timeIntervalSinceNow: 4 * 60 * 60) : nil
+            completionHandler(link, fileObject, expiration, serverError ?? error)
        })
        task.resume()
    }
    
-    open func copyItem(path: String, toRemoteURL destURL: URL, completionHandler: @escaping ((_ jobId: String?, _ attribute: DropboxFileObject?, _ error: Error?) -> Void)) {
+    /**
+     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 = ["path": correctPath(path)! as NSString, "url" : destURL.absoluteString as NSString]
+        let requestDictionary: [String: AnyObject] = ["path": correctPath(toPath)! as NSString, "url" : remoteURL.absoluteString as NSString]
        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
        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: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
+                serverError = 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) {
                    jobId = json["async_job_id"] as? String
                    if let attribDic = json["metadata"] as? [String: AnyObject] {
-                        fileObject = self.mapToFileObject(attribDic)
+                        fileObject = DropboxFileObject(json: attribDic)
                    }
                }
            }
-            completionHandler(jobId, fileObject, dbError ?? error)
+            completionHandler(jobId, fileObject, serverError ?? error)
+        })
+        task.resume()
+    }
+    
+    /**
+     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)
+        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
+            var serverError: FileProviderDropboxError?
+            if let response = response as? HTTPURLResponse {
+                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
+                serverError = code != nil ? FileProviderDropboxError(code: code!, path: toPath, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
+            }
+            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
@@ -355,7 +472,7 @@ 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":
@@ -370,7 +487,7 @@ 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":
@@ -386,7 +503,7 @@ extension DropboxFileProvider: ExtendedFileProvider {
        }
        var request = URLRequest(url: url)
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
-        var requestDictionary = ["path": path as NSString]
+        var requestDictionary: [String: AnyObject] = ["path": path as NSString]
        requestDictionary["format"] = "jpeg" as NSString
        if let dimension = dimension {
            requestDictionary["size"] = "w\(Int(dimension.width))h\(Int(dimension.height))" as NSString
@@ -413,26 +530,26 @@ 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 = ["path": correctPath(path)! as NSString, "include_media_info": NSNumber(value: true)]
+        let requestDictionary: [String: AnyObject] = ["path": correctPath(path)! as NSString, "include_media_info": NSNumber(value: true)]
        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
        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
+                serverError = 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] {
                    (dic, keys) = self.mapMediaInfo(properties)
                }
            }
-            completionHandler(dic, keys, dbError ?? error)
+            completionHandler(dic, keys, serverError ?? error)
        })
        task.resume()
    }
@@ -440,7 +557,7 @@ extension DropboxFileProvider: ExtendedFileProvider {

 extension DropboxFileProvider: FileProvider {
    open func copy(with zone: NSZone? = nil) -> Any {
-        let copy = DropboxFileProvider(credential: self.credential, cache: self.cache)!
+        let copy = DropboxFileProvider(credential: self.credential, cache: self.cache)
        copy.currentPath = self.currentPath
        copy.delegate = self.delegate
        copy.fileOperationDelegate = self.fileOperationDelegate
@@ -8,50 +8,72 @@

 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(absoluteURL: URL(string: path), name: name, path: path)
+        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 }
+        self.init(json: json)
+    }
+    
+    internal convenience init? (json: [String: AnyObject]) {
+        guard let name = json["name"] as? String else { return nil }
+        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.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[.serverDate] as? Date
        }
        set {
-            allValues["NSURLServerDateKey"] = newValue
+            allValues[.serverDate] = 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)) {
        var requestDictionary = [String: AnyObject]()
@@ -79,7 +101,7 @@ internal extension DropboxFileProvider {
                let json = jsonToDictionary(jsonStr)
                if let entries = json?["entries"] as? [AnyObject] , entries.count > 0 {
                    for entry in entries {
-                        if let entry = entry as? [String: AnyObject], let file = self.mapToFileObject(entry) {
+                        if let entry = entry as? [String: AnyObject], let file = DropboxFileObject(json: entry) {
                            files.append(file)
                        }
                    }
@@ -98,18 +120,23 @@ internal extension DropboxFileProvider {
    }
    
    func upload_simple(_ targetPath: String, data: Data, modifiedDate: Date = Date(), overwrite: Bool, operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        assert(data.count < 150*1024*1024, "Maximum size of allowed size to upload is 150MB")
-        var requestDictionary = [String: Any]()
+        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"] = string(from:modifiedDate)
+        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 as [String : AnyObject]), forHTTPHeaderField: "Dropbox-API-Arg")
+        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?
@@ -125,17 +152,24 @@ internal extension DropboxFileProvider {
    }
    
    func upload_simple(_ targetPath: String, localFile: URL, modifiedDate: Date = Date(), overwrite: Bool, operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        var requestDictionary = [String: Any]()
+        let size = (try? localFile.resourceValues(forKeys: [.fileSizeKey]))?.fileSize ?? -1
+        if size > 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"] = string(from:modifiedDate)
+        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 as [String : AnyObject]), forHTTPHeaderField: "Dropbox-API-Arg")
+        request.setValue(dictionaryToJSON(requestDictionary), forHTTPHeaderField: "Dropbox-API-Arg")
        let task = session.uploadTask(with: request, fromFile: localFile, completionHandler: { (data, response, error) in
            var responseError: FileProviderDropboxError?
            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
@@ -169,7 +203,7 @@ internal extension DropboxFileProvider {
                let json = jsonToDictionary(jsonStr)
                if let entries = json?["matches"] as? [AnyObject] , entries.count > 0 {
                    for entry in entries {
-                        if let entry = entry as? [String: AnyObject], let file = self.mapToFileObject(entry) {
+                        if let entry = entry as? [String: AnyObject], let file = DropboxFileObject(json: entry) {
                            foundItem(file)
                        }
                    }
@@ -191,25 +225,6 @@ internal extension DropboxFileProvider {
 // codebeat:enable[ARITY]

 internal extension DropboxFileProvider {
-    func mapToFileObject(_ jsonStr: String) -> DropboxFileObject? {
-        guard let json = jsonToDictionary(jsonStr) else { return nil }
-        return self.mapToFileObject(json)
-    }
-    
-    func mapToFileObject(_ json: [String: AnyObject]) -> DropboxFileObject? {
-        guard let name = json["name"] as? String else { return nil }
-        guard let path = json["path_display"] as? String else { return nil }
-        let fileObject = DropboxFileObject(name: name, path: path)
-        fileObject.size = (json["size"] as? NSNumber)?.int64Value ?? -1
-        fileObject.serverTime = resolve(dateString: json["server_modified"] as? String ?? "")
-        fileObject.modifiedDate = resolve(dateString: json["client_modified"] as? String ?? "")
-        fileObject.type = (json[".tag"] as? String) == "folder" ? .directory : .regular
-        fileObject.isReadOnly = (json["sharing_info"]?["read_only"] as? NSNumber)?.boolValue ?? false
-        fileObject.id = json["id"] as? String
-        fileObject.rev = json["rev"] as? String
-        return fileObject
-    }
-    
    static let dateFormatter = DateFormatter()
    static let decimalFormatter = NumberFormatter()
    
@@ -229,7 +244,7 @@ internal extension DropboxFileProvider {
            let longStr = DropboxFileProvider.decimalFormatter.string(from: NSNumber(value: longitude))
            dic["Location"] = "\(latStr), \(longStr)"
        }
-        if let timeTakenStr = json["time_taken"] as? String, let timeTaken = self.resolve(dateString: timeTakenStr) {
+        if let timeTakenStr = json["time_taken"] as? String, let timeTaken = resolve(dateString: timeTakenStr) {
            keys.append("Date taken")
            DropboxFileProvider.dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
            dic["Date taken"] = DropboxFileProvider.dateFormatter.string(from: timeTaken)
@@ -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:
@@ -61,10 +55,11 @@ 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
-            let fileURL = self.absoluteURL(path)
+            let fileURL = self.url(of: path)
            // Create Thumbnail and cache
            switch fileURL.pathExtension.lowercased() {
            case LocalFileInformationGenerator.videoThumbnailExtensions:
@@ -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)
            }
        }
@@ -117,35 +112,88 @@ extension LocalFileProvider: ExtendedFileProvider {
            var dic = [String: Any]()
            var keys = [String]()
            if let getterMethod = getter {
-                (dic, keys) = getterMethod(self.absoluteURL(path))
+                (dic, keys) = getterMethod(self.url(of: path))
            }
            
            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 +223,36 @@ 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)
    }
    
+    /// 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 {
+                keys.append(key)
+                dic[key] = value
+            }
+        }
+        
        func simplify(_ top:Int64, _ bottom:Int64) -> (newTop:Int, newBottom:Int) {
            var x = top
            var y = bottom
@@ -202,79 +267,58 @@ 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)"
-        }
-        if let dpi = imageDict[kCGImagePropertyDPIWidth as String] {
-            keys.append("DPI")
-            dic["DPI"] = dpi
-        }
-        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
+        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)")
        }
+        
+        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)
        if let cr = tiffDict[kCGImagePropertyTIFFCopyright as String] as? String , !cr.isEmpty {
-            keys.append("Copyright")
-            dic["Copyright"] = cr
+            add(key: "Copyright", value: cr)
+
        }
        if let date = tiffDict[kCGImagePropertyTIFFDateTime as String] as? String , !date.isEmpty {
-            keys.append("Date taken")
-            dic["Date taken"] = date
+            add(key: "Date taken", value: 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 latitude = tiffDict[kCGImagePropertyGPSLatitude as String] as? NSNumber, let longitude = tiffDict[kCGImagePropertyGPSLongitude as String] as? NSNumber {
+            add(key: "Location", value: "\(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)"
+        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 * 10_000_000_000_000), 10_000_000_000_000)
+            add(key: "Exposure time", value: "\(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: "ISO speed", value: iso[0])
        }
        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 +330,6 @@ 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 +342,25 @@ 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: LocalFileProvider.formatshort(interval: ap.duration))
+                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
@@ -328,17 +375,14 @@ public struct LocalFileInformationGenerator {
            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)"
+            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: LocalFileProvider.formatshort(interval: TimeInterval(duration)))
+            add(key: "Video Bitrate", value: "\(Int(ceil(bitrate / 1000))) kbps")
        }
        let audioTracks = asset.tracks(withMediaType: AVMediaTypeAudio)
        // dic["Audio channels"] = audioTracks.count
@@ -346,12 +390,22 @@ 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 {
+                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!) {
@@ -377,67 +431,57 @@ 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
+                add(key: "Title", value: title)
            }
            if let author = getKey("Author", from: dict), !author.isEmpty {
-                keys.append("Author")
-                dic["Author"] = author
+                add(key: "Author", value: author)
            }
            if let subject = getKey("Subject", from: dict), !subject.isEmpty {
-                keys.append("Subject")
-                dic["Subject"] = subject
+                add(key: "Subject", value: subject)
            }
            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
+                add(key: "Content creator", value: creator)
            }
-            if let creationDateString = getKey("CreationDate", from: dict), let creationDate = convertDate(creationDateString) {
-                keys.append("Creation date")
-                dic["Creation date"] = creationDate
+            if let creationDateString = getKey("CreationDate", from: dict) {
+                add(key: "Creation date", value: convertDate(creationDateString))
            }
-            if let modifiedDateString = getKey("ModDate", from: dict), let modDate = convertDate(modifiedDateString) {
-                keys.append("Modified date")
-                dic["Modified date"] = modDate
+            if let modifiedDateString = getKey("ModDate", from: dict) {
+                add(key: "Modified date", value: convertDate(modifiedDateString))
            }
-            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: "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)
 }
@@ -13,8 +13,7 @@ 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 {
+internal class FPSStreamTask: URLSessionTask, StreamDelegate {
    fileprivate var inputStream: InputStream?
    fileprivate var outputStream: OutputStream?
    
@@ -449,23 +448,23 @@ open class FPSStreamTask: URLSessionTask, StreamDelegate {
    }
 }

-extension URLSession {
+internal extension URLSession {
    /* Creates a bidirectional stream task to a given host and port.
     */
-    public func fpstreamTaskWithHostName(_ hostname: String, port: Int) -> FPSStreamTask {
+    func fpstreamTaskWithHostName(_ hostname: String, port: Int) -> FPSStreamTask {
        return FPSStreamTask(session: self, host: hostname, port: port)
    }
    
    /* 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 {
+    func fpstreamTaskWithNetService(_ service: NetService) -> FPSStreamTask {
        return fpstreamTaskWithNetService(service)
    }
 }

@objc
-public protocol FPSStreamDelegate : URLSessionTaskDelegate {
+internal protocol FPSStreamDelegate : URLSessionTaskDelegate {
    
    
    /* Indiciates that the read side of a connection has been closed.  Any
@@ -8,92 +8,101 @@

 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(absoluteURL: URL? = nil, name: String, path: String) {
-        self.allValues = [String: Any]()
-        self.absoluteURL = absoluteURL
+    internal init(url: URL, name: String, path: String) {
+        self.allValues = [URLResourceKey: Any]()
+        self.url = url
        self.name = name
        self.path = path
    }
    
    /// url to access the resource, not supported by Dropbox provider
-    open internal(set) var absoluteURL: URL? {
+    @available(*, deprecated, renamed: "url", message: "Use 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["NSURLAbsoluteURLKey"] as? URL
+            return allValues[.fileURL] as? URL
        }
        set {
-            allValues["NSURLAbsoluteURLKey"] = newValue
+            allValues[.fileURL] = 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.")
+    /// **OBSOLETED:** Use `type` property instead.
+    @available(*, obsoleted: 1.0, renamed: "type", message: "Use type property instead.")
    open var fileType: URLFileResourceType? {
        return self.type
    }
@@ -102,20 +111,20 @@ open class FileObject {
    /// 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
        }
    }
    
@@ -133,9 +142,73 @@ open class FileObject {
    open var isSymLink: Bool {
        return self.type == .symbolicLink
    }
+    
+    /// 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
+    }
+    
+    internal  func mapPredicate() -> [String: Any] {
+        let mapDict: [URLResourceKey: String] = [.fileURL: "url", .nameKey: "name", .pathKey: "path", .fileSizeKey: "filesize", .creationDateKey: "creationDate",
+                                                 .contentModificationDateKey: "modifiedDate", .isHiddenKey: "isHidden", .isWritableKey: "isWritable", .serverDate: "serverDate", .entryTag: "entryTag", .mimeType: "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
+    }
 }

-/// Sorting FileObject array by given criteria, not thread-safe
+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
+    }
+    
+    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)
+}
+
+/// Sorting FileObject array by given criteria, **not thread-safe**
 public struct FileObjectSorting {
    
    /// Determines sort kind by which item of File object
@@ -179,13 +252,19 @@ 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 properties
    public func sort(_ files: [FileObject]) -> [FileObject] {
        return files.sorted {
            if isDirectoriesFirst {
@@ -222,7 +301,21 @@ public struct FileObjectSorting {
    }
 }

+extension Array where Element: FileObject {
+    /// Returns a sorted array of `FileObject`s by criterias set in properties.
+    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 properties
+    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
@@ -237,6 +330,13 @@ extension URLFileResourceType {
    }
 }

+internal extension URLResourceKey {
+    static let fileURL = URLResourceKey(rawValue: "NSURLFileURLKey")
+    static let serverDate = URLResourceKey(rawValue: "NSURLServerDateKey")
+    static let entryTag = URLResourceKey(rawValue: "NSURLEntryTagKey")
+    static let mimeType = URLResourceKey(rawValue: "NSURLMIMETypeIdentifierKey")
+}
+
 internal extension URL {
    var uw_scheme: String {
        return self.scheme ?? ""
@@ -15,29 +15,230 @@ import Cocoa
 public typealias ImageClass = NSImage
 #endif

+/// Completion handler type with an error argument
 public typealias SimpleCompletionHandler = ((_ error: Error?) -> Void)?

+/// This protocol defines FileProvider neccesary functions and properties to connect and get contents list
 public protocol FileProviderBasic: class {
+    /// An string to identify type of provider.
    static var type: String { get }
+    
+    /// An string to identify type of provider.
+    var type: String { get }
+    
+    /// The paths in arguments should resolved against base url.
    var isPathRelative: Bool { get }
+    
+    /// The url of which paths should resolve against.
    var baseURL: URL? { get }
+    
+    /// Current active path used in `contentsOfDirectory(path:completionHandler:)` method.
    var currentPath: String { get set }
+    
+    /**
+     Dispatch queue usually used in query methods.
+     Set it to a new object to switch between cuncurrent and serial queues.
+     - **Default:** Cuncurrent `DispatchQueue` object.
+    */
    var dispatch_queue: DispatchQueue { get set }
+    
+    /// Operation queue ususlly used in file operation methods.
+    /// use `maximumOperationTasks` property of provider to manage operation queue.
+    var operation_queue: OperationQueue { get set }
+    
+    /// Delegate to update UI after finishing file operations.
    var delegate: FileProviderDelegate? { get set }
+    
+    /**
+     login credential for provider. Should be set in `init` method.
+     
+     **Example initialization:**
+     ````
+     let credential = URLCredential(user: "user", password: "password", persistence: .forSeession)
+     ````
+     
+     - Note: In OAuth based providers like `DropboxFileProvider` and `OneDriveFileProvider`, password is Token.
+     use [OAuthSwift](https://github.com/OAuthSwift/OAuthSwift) library to fetch clientId and Token of user.
+     */
    var credential: URLCredential? { get }
    
+    /**
+     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.
+     */
    func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void))
+    
+    /**
+     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.
+     */
    func attributesOfItem(path: String, completionHandler: @escaping ((_ attributes: FileObject?, _ error: Error?) -> Void))
    
+    
+    /// Returns total and used capacity in provider container asynchronously.
    func storageProperties(completionHandler: @escaping ((_ total: Int64, _ used: Int64) -> Void))
    
+    /**
+     Search files inside directory using query asynchronously.
+     
+     - Note: Query string is limited to file name, to search based on other file properties, use NSPredicate version.
+     
+     - Parameters:
+       - path: location of directory to start search
+       - recursive: Searching subdirectories of path
+       - query: Simple string that file name contains to be search, case-insensitive.
+       - 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.
+     */
+    func searchFiles(path: String, recursive: Bool, query: String, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void))
+    
+    /**
+     Search files inside directory using query asynchronously.
+     
+     Sample predicates:
+     ```
+     NSPredicate(format: "(name CONTAINS[c] 'hello') && (filesize >= 10000)")
+     NSPredicate(format: "(modifiedDate >= %@)", Date())
+     NSPredicate(format: "(path BEGINSWITH %@)", "folder/child folder")
+     ```
+     
+     - Note: Don't pass Spotlight predicates to this method directly, use `FileProvider.convertSpotlightPredicateTo()` method to get usable predicate.
+     
+     - Parameters:
+       - path: location of directory to start search
+       - recursive: Searching subdirectories of path
+       - query: An `NSPredicate` object with keys like `FileObject` members, except `size` which becomes `filesize`.
+       - 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.
+     */
+    func searchFiles(path: String, recursive: Bool, query: NSPredicate, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void))
+    
+    /**
+     Returns an independent url to access the file. Some providers like `Dropbox` due to their nature.
+     don't return an absolute url to be used to access file directly.
+     - Parameter path: Relative path of file or directory.
+     - Returns: An url, can be used to access to file directly.
+    */
    func url(of path: String?) -> URL
+    
+    /// Checks the connection to server or permission on local
+    func isReachable(completionHandler: @escaping(_ success: Bool) -> Void)
 }

+extension FileProviderBasic {
+    public func searchFiles(path: String, recursive: Bool, query: String, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
+        let predicate = NSPredicate(format: "name CONTAINS[c] %@", query)
+        self.searchFiles(path: path, recursive: recursive, query: predicate, foundItemHandler: foundItemHandler, completionHandler: completionHandler)
+    }
+    
+    /// Converts Spotlight search predicate to `FileProvider.searchFiles()` method usable predicate.
+    public func convertSpotlightPredicateTo(_ query: NSPredicate) -> NSPredicate {
+        let mapDict: [String: URLResourceKey] = [NSMetadataItemURLKey: .fileURL, NSMetadataItemFSNameKey: .nameKey, NSMetadataItemPathKey: .pathKey,
+                                                 NSMetadataItemFSSizeKey: .fileSizeKey, NSMetadataItemFSCreationDateKey: .creationDateKey,
+                                                 NSMetadataItemFSContentChangeDateKey: .contentModificationDateKey, "kMDItemFSInvisible": .isHiddenKey, "kMDItemFSIsWriteable": .isWritableKey, "kMDItemKind": .mimeType]
+        
+        if let cQuery = query as? NSCompoundPredicate {
+            let newSub = cQuery.subpredicates.map { convertSpotlightPredicateTo($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
+        }
+    }
+    
+    /// The maximum number of queued operations that can execute at the same time.
+    ///
+    /// The default value of this property is `OperationQueue.defaultMaxConcurrentOperationCount`.
+    public var maximumOperationTasks: Int {
+        get {
+            return operation_queue.maxConcurrentOperationCount
+        }
+        set {
+            operation_queue.maxConcurrentOperationCount = newValue
+        }
+    }
+    
+    internal func findNameQuery(_ query: NSPredicate, key: String?) -> Any? {
+        if let cQuery = query as? NSCompoundPredicate {
+            let find = cQuery.subpredicates.flatMap { findNameQuery($0 as! NSPredicate, key: key) }
+            if find.count > 0 {
+                return find[0]
+            }
+            return nil
+        } else if let cQuery = query as? NSComparisonPredicate {
+            if cQuery.leftExpression.expressionType == .keyPath, key == nil || cQuery.leftExpression.keyPath == key! {
+                return cQuery.rightExpression.constantValue
+            }
+            if cQuery.rightExpression.expressionType == .keyPath, key == nil || cQuery.rightExpression.keyPath == key! {
+                return cQuery.leftExpression.constantValue
+            }
+            return nil
+        } else {
+            return nil
+        }
+    }
+}
+
+/// Checking equality of two file provider, regardless of current path queues and delegates.
+public func ==(lhs: FileProviderBasic, rhs: FileProviderBasic) -> Bool {
+    if lhs === rhs { return true }
+    if type(of: lhs) != type(of: rhs) {
+        return false
+    }
+    return lhs.type == rhs.type && lhs.baseURL == rhs.baseURL && lhs.isPathRelative == rhs.isPathRelative && lhs.credential == rhs.credential
+}
+
+/// Cancels all active underlying tasks
+public var fileProviderCancelTasksOnInvalidating = true
+
+/// Extending `FileProviderBasic` for web-based file providers
 public protocol FileProviderBasicRemote: FileProviderBasic {
+    /// Underlying URLSession instance used for HTTP/S requests
    var session: URLSession { get }
+    
+    /**
+     A `URLCache` to cache downloaded files and contents.
+     
+     - Note: It has no effect unless setting `useCache` property to `true`.
+     
+     - Warning: FileProvider doesn't manage/free `URLCache` object in a memory pressure scenario. It's upon you to clear
+     cache memory when receiving `didReceiveMemoryWarning` or via observing `.UIApplicationDidReceiveMemoryWarning` notification.
+     To clear memory usage use this code:
+     ```
+     provider.cache?.removeAllCachedResponses()
+     ```
+     */
    var cache: URLCache? { get }
+    
+    /// Determine to use `cache` property to cache downloaded file objects. Doesn't have effect on query type methods.
    var useCache: Bool { get set }
+    
+    /// Validating cached data using E-Tag or Revision identifier if possible.
    var validatingCache: Bool { get set }
 }

@@ -89,27 +290,145 @@ internal extension FileProviderBasicRemote {
    }
 }

+/// Defines methods for common file operaions including create, copy/move and delete
 public protocol FileProviderOperations: FileProviderBasic {
+    /// Delgate for managing operations involving the copying, moving, linking, or removal of files and directories. When you use an FileManager object to initiate a copy, move, link, or remove operation, the file provider asks its delegate whether the operation should begin at all and whether it should proceed when an error occurs.
    var fileOperationDelegate : FileOperationDelegate? { get set }
    
+    /**
+     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 `LocalFileProvider`.
+     */
    @discardableResult
    func create(folder: String, at: String, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     Creates an new file with data passed to method asynchronously. 
+     Returns error via completionHandler if file is already exists.
+     
+     - Parameters:
+       - file: New file name with extension separated by period.
+       - at: Parent path of new file.
+       - data: Data of new files. Pass nil or `Data()` to create empty file.
+       - 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
    func create(file: String, at: String, contents data: Data?, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     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. If file is already exist, an error will be returned via completionHandler.
+     
+     - Parameters:
+       - path: original file or directory path.
+       - to: destination path of file or directory, 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. Doesn't work on `LocalFileProvider`.
+     */
    @discardableResult
    func moveItem(path: String, to: String, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     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 `LocalFileProvider`.
+     */
    @discardableResult
    func moveItem(path: String, to: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     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. If file is already exist, an error will be returned via completionHandler.
+     
+     - Parameters:
+       - path: original file or directory path.
+       - to: destination path of file or directory, 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. Doesn't work on `LocalFileProvider`.
+     */
    @discardableResult
    func copyItem(path: String, to: String, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     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 `LocalFileProvider`.
+     */
    @discardableResult
    func copyItem(path: String, to: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     Removes the file or directory at the specified path.
+     
+     - 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 `LocalFileProvider`.
+     
+     */
    @discardableResult
    func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     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.
+       - completionHandler: If an error parameter was provided, a presentable `Error` will be returned.
+     - Returns: An `OperationHandle` to get progress or cancel progress.
+     */
    @discardableResult
    func copyItem(localFile: URL, to: String, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     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
    func copyItem(localFile: URL, to: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     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. Doesn't work on `LocalFileProvider`.
+     */
    @discardableResult
    func copyItem(path: String, toLocalURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle?
 }
@@ -131,22 +450,93 @@ extension FileProviderOperations {
    }
 }

+/// Defines method for fetching and modifying file contents
 public protocol FileProviderReadWrite: FileProviderBasic {
+    /**
+     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. Doesn't work on `LocalFileProvider`.
+    */
    @discardableResult
    func contents(path: String, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle?
+    
+    /**
+     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. Doesn't work on `LocalFileProvider`.
+     */
    @discardableResult
    func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle?
    
+    /**
+     Write the contents of the `Data` to a location asynchronously.
+     It will return error if file is already exists.
+     Not attomically by default, unless the provider enforces it.
+     
+     - Parameters:
+       - path: Path of target file.
+       - contents: Data to be written into file.
+       - 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
    func writeContents(path: String, contents: Data, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     Write the contents of the `Data` to a location asynchronously.
+     It will return error if file is already exists.
+     
+     - Parameters:
+       - path: Path of target file.
+       - contents: Data to be written into file.
+       - 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
    func writeContents(path: String, contents: Data, atomically: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     Write the contents of the `Data` to a location asynchronously.
+     Not attomically by default, unless the provider enforces it.
+     
+     - 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`.
+       - 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
    func writeContents(path: String, contents: Data, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle?
+    
+    /**
+     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
    func writeContents(path: String, contents: Data, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle?
-    
-    func searchFiles(path: String, recursive: Bool, query: String, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void))
 }

 extension FileProviderReadWrite {
@@ -171,21 +561,99 @@ extension FileProviderReadWrite {
    }
 }

+/// Allows a file provider to notify changes occured
 public protocol FileProviderMonitor: FileProviderBasic {
+    
+    /**
+     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.
+     */
    func registerNotifcation(path: String, eventHandler: @escaping (() -> Void))
+    
+    /// Stops monitoring the path.
+    ///
+    /// - Parameter path: path of directory.
    func unregisterNotifcation(path: String)
+    
+    /// Investigate either the path is registered for change notification or not.
+    ///
+    /// - Parameter path: path of directory.
+    /// - Returns: Directory is being monitored or not.
    func isRegisteredForNotification(path: String) -> Bool
 }

+/// Allows undo file operations done by provider
+public protocol FileProvideUndoable: FileProviderOperations {
+    /// To initialize undo manager either call `setupUndoManager()` or set it manually.
+    ///
+    /// - Note: Only some operations (moving/renaming, copying and creating) are supported for undoing.
+    /// - Note: recording operations will occur after setting this object.
+    var undoManager: UndoManager? { get set }
+    
+    /// UndoManager supports undoing this file operation
+    func canUndo(handle: OperationHandle) -> Bool
+    /// UndoManager supports undoing this operation
+    func canUndo(operation: FileOperationType) -> Bool
+}
+
+public extension FileProvideUndoable {
+    public func canUndo(operation: FileOperationType) -> Bool {
+        return undoOperation(for: operation) != nil
+    }
+    
+    public func canUndo(handle: OperationHandle) -> Bool {
+        return canUndo(operation: handle.operationType)
+    }
+    
+    internal func undoOperation(for operation: FileOperationType) -> FileOperationType? {
+        switch operation {
+        case .create(path: let path):
+            return .remove(path: path)
+        case .modify(path: _):
+            return nil
+        case .copy(source: _, destination: let dest):
+            return .remove(path: dest)
+        case .move(source: let source, destination: let dest):
+            return .move(source: dest, destination: source)
+        case .link(link: let link, target: _):
+            return .remove(path: link)
+        case .remove(path: _):
+            return nil
+        default:
+            return nil
+        }
+    }
+    
+    /// Initiates `self.undoManager` if equals with `nil`, and set `levelsOfUndo` to 10.
+    public func setupUndoManager() {
+        guard self.undoManager == nil else { return }
+        self.undoManager = UndoManager()
+        self.undoManager?.levelsOfUndo = 10
+    }
+}
+
+/// Defines protocol for provider allows all common operations.
 public protocol FileProvider: FileProviderBasic, FileProviderOperations, FileProviderReadWrite, NSCopying {
 }

-fileprivate let pathTrimSet = CharacterSet(charactersIn: " /")
+internal let pathTrimSet = CharacterSet(charactersIn: " /")
 extension FileProviderBasic {
    public var type: String {
-        return Self.type
+        return type(of: self).type
    }
    
+    /// path without heading and trailing slash
    public var bareCurrentPath: String {
        return currentPath.trimmingCharacters(in: pathTrimSet)
    }
@@ -194,6 +662,8 @@ extension FileProviderBasic {
        return path.trimmingCharacters(in: pathTrimSet).addingPercentEncoding(withAllowedCharacters: .urlPathAllowed)!
    }
    
+    /// **OBSOLETED:** Use `url(of:).absoluteURL` instead.
+    @available(*, obsoleted: 1.0, renamed: "url(of:)", message: "Use url(of:).absoluteURL instead.")
    public func absoluteURL(_ path: String? = nil) -> URL {
        return url(of: path).absoluteURL
    }
@@ -216,9 +686,24 @@ extension FileProviderBasic {
        }
    }
    
+    
+    /// Returns the relative path of url, wothout percent encoding. Even if url is absolute or
+    /// retrieved from another provider, it will try to resolve the url against `baseURL` of
+    /// current provider. It's highly recomended to use this method for displaying purposes.
+    ///
+    /// - Parameter url: Absolute url to file or directory.
+    /// - Returns: A `String` contains relative path of url against base url.
    public func relativePathOf(url: URL) -> String {
-        guard let baseURL = self.baseURL else { return url.absoluteString }
-        return url.standardizedFileURL.absoluteString.replacingOccurrences(of: baseURL.absoluteString, with: "/").removingPercentEncoding!
+        // check if url derieved from current base url
+        if !url.relativePath.isEmpty, url.baseURL == self.baseURL {
+            return url.relativePath.removingPercentEncoding!
+        }
+        
+        // resolve url string against baseurl
+        guard let baseURL = self.baseURL?.standardizedFileURL else { return url.absoluteString }
+        let standardPath = url.absoluteString.replacingOccurrences(of: "file:///private/var/", with: "file:///var/", options: .anchored)
+        let standardBase = baseURL.absoluteString.replacingOccurrences(of: "file:///private/var/", with: "file:///var/", options: .anchored)
+        return standardPath.replacingOccurrences(of: standardBase, with: "/").removingPercentEncoding!
    }
    
    internal func correctPath(_ path: String?) -> String? {
@@ -230,6 +715,8 @@ extension FileProviderBasic {
        return p
    }
    
+    /// Returns a file name supposed to be unique with adding numbers to end of file.
+    /// - Important: It's a synchronous method. Don't use it on matin thread.
    public func fileByUniqueName(_ filePath: String) -> String {
        let fileUrl = URL(fileURLWithPath: filePath)
        let dirPath = fileUrl.deletingLastPathComponent().path 
@@ -251,7 +738,7 @@ extension FileProviderBasic {
            }
            var i = number ?? 2
            let similiar = contents.map {
-                $0.absoluteURL?.lastPathComponent ?? $0.name
+                $0.url?.lastPathComponent ?? $0.name
            }.filter {
                $0.hasPrefix(result)
            }
@@ -261,13 +748,13 @@ extension FileProviderBasic {
            }
            group.leave()
        }
-        _ = group.wait(timeout: DispatchTime.distantFuture)
+        _ = group.wait(timeout: DispatchTime.now() + 5)
        let finalFile = result + (!fileExt.isEmpty ? "." + fileExt : "")
        return (dirPath as NSString).appendingPathComponent(finalFile)
    }
    
    internal func throwError(_ path: String, code: FoundationErrorEnum) -> NSError {
-        let fileURL = self.absoluteURL(path)
+        let fileURL = self.url(of: path)
        let domain: String
        switch code {
        case is URLError:
@@ -278,47 +765,68 @@ extension FileProviderBasic {
        return NSError(domain: domain, code: code.rawValue, userInfo: [NSURLErrorFailingURLErrorKey: fileURL, NSURLErrorFailingURLStringErrorKey: fileURL.absoluteString])
    }
    
-    internal func NotImplemented() {
-        assert(false, "method not implemented")
+    internal func NotImplemented(_ fn: String = #function, file: StaticString = #file) {
+        assert(false, "\(fn) method is not yet implemented. \(file)")
    }
-    
-    internal func resolve(dateString: String) -> Date? {
-        let dateFor: DateFormatter = DateFormatter()
-        dateFor.locale = Locale(identifier: "en_US")
-        dateFor.dateFormat = "EEE',' dd' 'MMM' 'yyyy HH':'mm':'ss zzz"
-        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
-        }
-        dateFor.dateFormat = "yyyy'-'MM'-'dd'T'HH':'mm':'ssz"
-        if let isotime = dateFor.date(from: dateString) {
-            return isotime
-        }
-        return nil
-    }
-    
-    public func string(from 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)
-    }
-    
 }

+/// Define methods to get preview and thumbnail for files or folders
 public protocol ExtendedFileProvider: FileProviderBasic {
+    /// Returuns true if thumbnail preview is supported by provider and file type accordingly.
+    ///
+    /// - Parameter path: path of file.
+    /// - Returns: A `Bool` idicates path can have thumbnail.
    func thumbnailOfFileSupported(path: String) -> Bool
+    
+    /// Returns true if provider supports fetching properties of file like dimensions, duration, etc.
+    /// Usually media or document files support these meta-infotmations.
+    ///
+    /// - Parameter path: path of file.
+    /// - Returns: A `Bool` idicates path can have properties.
    func propertiesOfFileSupported(path: String) -> Bool
+    
+    /**
+     Generates ans returns a thumbnail preview of document asynchronously. The defualt dimension of returned image is different
+     regarding provider type, usually 64x64 pixels.
+     
+     - Parameters:
+       - path: path of file.
+       - completionHandler: a closure with result of preview image or error.
+         `image`: `NSImage`/`UIImage` object contains preview.
+         `error`: Error returned by system.
+    */
    func thumbnailOfFile(path: String, completionHandler: @escaping ((_ image: ImageClass?, _ error: Error?) -> Void))
+    
+    /**
+     Generates ans returns a thumbnail preview of document asynchronously. The defualt dimension of returned image is different
+     regarding provider type, usually 64x64 pixels. Default value used when `dimenstion` is `nil`.
+     
+     - Note: `LocalFileInformationGenerator` variables can be set to change default behavior of
+             thumbnail and properties generator of `LocalFileProvider`.
+     
+     - Parameters:
+       - path: path of file.
+       - dimension: width and height of result preview image.
+       - completionHandler: a closure with result of preview image or error.
+         `image`: `NSImage`/`UIImage` object contains preview.
+     `error`: Error returned by system.
+     */
    func thumbnailOfFile(path: String, dimension: CGSize?, completionHandler: @escaping ((_ image: ImageClass?, _ error: Error?) -> Void))
+    
+    /**
+     Fetching properties of file like dimensions, duration, etc. It's variant depending on file type.
+     Images, videos and audio files meta-information will be returned.
+     
+     - Note: `LocalFileInformationGenerator` variables can be set to change default behavior of 
+             thumbnail and properties generator of `LocalFileProvider`.
+     
+     - Parameters:
+       - path: path of file.
+       - completionHandler: a closure with result of preview image or error.
+         `propertiesDictionary`: A `Dictionary` of proprty keys and values.
+         `keys`: An `Array` contains ordering of keys.
+         `error`: Error returned by system.
+     */
    func propertiesOfFile(path: String, completionHandler: @escaping ((_ propertiesDictionary: [String: Any], _ keys: [String], _ error: Error?) -> Void))
 }

@@ -430,14 +938,14 @@ extension ExtendedFileProvider {
        let newSize = CGSize(width: width, height: height)
        
        #if os(macOS)
-            var imageRect = NSRect(origin: CGPoint.zero, size: image.size)
+            var imageRect = NSRect(origin: .zero, size: image.size)
            let imageRef = image.cgImage(forProposedRect: &imageRect, context: nil, hints: nil)
            
            // Create NSImage from the CGImage using the new size
            return NSImage(cgImage: imageRef!, size: newSize)
        #else
            UIGraphicsBeginImageContextWithOptions(newSize, false, 0.0)
-            image.draw(in: CGRect(origin: CGPoint.zero, size: newSize))
+            image.draw(in: CGRect(origin: .zero, size: newSize))
            let newImage = UIGraphicsGetImageFromCurrentImageContext() ?? image
            UIGraphicsEndImageContext()
            return newImage
@@ -445,13 +953,21 @@ extension ExtendedFileProvider {
    }
 }

+/// Operation type description of file operation, included files path in associated values.
 public enum FileOperationType: CustomStringConvertible {
+    /// Creating a file or directory in path.
    case create (path: String)
+    /// Copying a file or directory from source to destination.
    case copy   (source: String, destination: String)
+    /// Moving a file or directory from source to destination.
    case move   (source: String, destination: String)
+    /// Modifying data of a file o in path by writing new data.
    case modify (path: String)
+    /// Deleting file or directory in path.
    case remove (path: String)
+    /// Creating a symbolic link or alias to target.
    case link   (link: String, target: String)
+    /// Fetching data in file located in path.
    case fetch  (path: String)
    
    public var description: String {
@@ -466,16 +982,24 @@ public enum FileOperationType: CustomStringConvertible {
        }
    }
    
+    /// present participle of action, like `Copying`.
    public var actionDescription: String {
        return description.trimmingCharacters(in: CharacterSet(charactersIn: "e")) + "ing"
    }
    
+    /// Path of subjecting file.
    public var source: String? {
        guard let reflect = Mirror(reflecting: self).children.first?.value else { return nil }
        let mirror = Mirror(reflecting: reflect)
        return reflect as? String ?? mirror.children.first?.value as? String
    }
    
+    /// Path of subjecting file.
+    public var path: String? {
+        return source
+    }
+    
+    /// Path of destination file.
    public var destination: String? {
        guard let reflect = Mirror(reflecting: self).children.first?.value else { return nil }
        let mirror = Mirror(reflecting: reflect)
@@ -490,13 +1014,24 @@ public enum FileOperationType: CustomStringConvertible {
    }
 }

-
+/// Allows to get progress or cancel an in-progress operation, useful for remote providers
 public protocol OperationHandle {
+    /// Operation supposed to be done on files. Contains file paths as associated value.
    var operationType: FileOperationType { get }
+    
+    /// Bytes written/read by operation so far.
    var bytesSoFar: Int64 { get }
+    
+    /// Total bytes of operation.
    var totalBytes: Int64 { get }
+    
+    /// Operation is progress or not, Returns false if operation is done or not initiated yet.
    var inProgress: Bool { get }
+    
+    /// Progress of operation, usually equals with `bytesSoFar/totalBytes`. or NaN if not available.
    var progress: Float { get }
+    
+    /// Cancels operation while in progress, or cancels data/download/upload url session task.
    func cancel() -> Bool
 }

@@ -508,12 +1043,23 @@ public extension OperationHandle {
    }
 }

+/// Delegate methods for reporting provider's operation result and progress, when it's ready to update
+/// user interface.
+/// All methods are called in main thread to avoids UI bugs.
 public protocol FileProviderDelegate: class {
+    /// fileproviderSucceed(_:operation:) gives delegate a notification when an operation finished with success.
+    /// This method is called in main thread to avoids UI bugs.
    func fileproviderSucceed(_ fileProvider: FileProviderOperations, operation: FileOperationType)
+    /// fileproviderSucceed(_:operation:) gives delegate a notification when an operation finished with failure.
+    /// This method is called in main thread to avoids UI bugs.
    func fileproviderFailed(_ fileProvider: FileProviderOperations, operation: FileOperationType)
+    /// fileproviderSucceed(_:operation:) gives delegate a notification when an operation progess.
+    /// Supported by some providers, especially remote ones.
+    /// This method is called in main thread to avoids UI bugs.
    func fileproviderProgress(_ fileProvider: FileProviderOperations, operation: FileOperationType, progress: Float)
 }

+/// The `FileOperationDelegate` protocol defines methods for managing operations involving the copying, moving, linking, or removal of files and directories. When you use an `FileProvider` object to initiate a copy, move, link, or remove operation, the file provider asks its delegate whether the operation should begin at all and whether it should proceed when an error occurs.
 public protocol FileOperationDelegate: class {
    
    /// fileProvider(_:shouldOperate:) gives the delegate an opportunity to filter the file operation. Returning true from this method will allow the copy to happen. Returning false from this method causes the item in question to be skipped. If the item skipped was a directory, no children of that directory will be subject of the operation, nor will the delegate be notified of those children.
@@ -530,6 +1076,7 @@ internal class Weak<T: AnyObject> {
    }
 }

+/// For internal use in `FileProvider` framework
 public protocol FoundationErrorEnum {
    init? (rawValue: Int)
    var rawValue: Int { get }
@@ -8,305 +8,479 @@

 import Foundation

-open class LocalFileProvider: FileProvider, FileProviderMonitor {
-    open static let type = "Local"
-    open var isPathRelative: Bool = true
-    open private(set) var baseURL: URL? = LocalFileProvider.defaultBaseURL()
-    open var currentPath: String = ""
+/**
+ 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 var isPathRelative: Bool
+    open fileprivate(set) var baseURL: URL?
+    open var currentPath: String
    open var dispatch_queue: DispatchQueue
-    open var operation_queue: DispatchQueue
+    open var operation_queue: OperationQueue
    open weak var delegate: FileProviderDelegate?
-    open let credential: URLCredential? = nil
-        
+    open internal(set) 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
    
-    public init () {
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(LocalFileProvider.type)", attributes: DispatchQueue.Attributes.concurrent)
-        operation_queue = DispatchQueue(label: "FileProvider.\(LocalFileProvider.type).Operation", attributes: [])
-        fileProviderManagerDelegate = LocalFileProviderManagerDelegate(provider: self)
-        opFileManager.delegate = fileProviderManagerDelegate
+    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
+    
+    /**
+     Initializes provider for the specified common directory in the requested domains.
+     default values are `directory: .documentDirectory, domainMask: .userDomainMask`.
+     
+     - Parameters:
+       - directory: The search path directory. The supported values are described in `FileManager.SearchPathDirectory`.
+       - domainMask: The file system domain to search. The value for this parameter is one or more of the constants described in `FileManager.SearchPathDomainMask`.
+    */
+    public convenience init (directory: FileManager.SearchPathDirectory = .documentDirectory, domainMask: FileManager.SearchPathDomainMask = .userDomainMask) {
+        self.init(baseURL: FileManager.default.urls(for: directory, in: domainMask).first!)
    }
    
+    /**
+     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
+        
+        switch directory {
+        case .documentDirectory:
+            finalBaseURL = baseURL.appendingPathComponent("Documents")
+        case .libraryDirectory:
+            finalBaseURL = baseURL.appendingPathComponent("Library")
+        case .cachesDirectory:
+            finalBaseURL = baseURL.appendingPathComponent("Library/Caches")
+        case .applicationSupportDirectory:
+            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
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(LocalFileProvider.type)", attributes: DispatchQueue.Attributes.concurrent)
-        operation_queue = DispatchQueue(label: "FileProvider.\(LocalFileProvider.type).Operation", attributes: [])
+        self.isPathRelative = true
+        self.currentPath = ""
+        self.credential = nil
+        self.isCoorinating = false
+        
+        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
+        
    }
    
-    open static func defaultBaseURL() -> URL {
-        let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true);
-        return URL(fileURLWithPath: paths[0])
+    /// **DEPRECATED:** No longer is in use and overriding this method has no effect anymore.
+    @available(*, deprecated, message: "Overriding this method has no effect anymore.")
+    open class func defaultBaseURL() -> URL {
+        return FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
    }
    
    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
        dispatch_queue.async {
            do {
-                let contents = try self.fileManager.contentsOfDirectory(at: self.absoluteURL(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)
                })
                completionHandler(filesAttributes, nil)
-            } catch let e as NSError {
+            } catch let e {
                completionHandler([], e)
            }
        }
    }
    
-    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 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) + "/")
-        operation_queue.async {
-            do {
-                try self.opFileManager.createDirectory(at: self.absoluteURL(atPath).appendingPathComponent(folderName), withIntermediateDirectories: true, attributes: [:])
-                completionHandler?(nil)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                })
-            } catch let e as NSError {
-                completionHandler?(e)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                })
-            }
-        }
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
+    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)
    }
    
-    @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))
-        operation_queue.async {
-            let fileURL = self.absoluteURL(atPath).appendingPathComponent(fileName)
-            let success = self.opFileManager.createFile(atPath: fileURL.path, contents: data, attributes: nil)
-            if success {
-                completionHandler?(nil)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                })
-            } else {
-                completionHandler?(self.throwError(atPath, code: URLError.cannotCreateFile as FoundationErrorEnum))
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                })
-            }
-        }
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
-    }
-    
-    @discardableResult
-    open func moveItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.move(source: path, destination: toPath)
-        operation_queue.async {
-            if !overwrite && self.fileManager.fileExists(atPath: self.absoluteURL(toPath).path) {
-                completionHandler?(self.throwError(toPath, code: URLError.cannotMoveFile as FoundationErrorEnum))
-                return
-            }
-            do {
-                try self.opFileManager.moveItem(at: self.absoluteURL(path), to: self.absoluteURL(toPath))
-                completionHandler?(nil)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                })
-            } catch let e as NSError {
-                completionHandler?(e)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                })
-            }
-        }
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
-    }
-    
-    @discardableResult
-    open func copyItem(path: String, to toPath: String, overwrite: Bool = false, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.copy(source: path, destination: toPath)
-        operation_queue.async {
-            if !overwrite && self.fileManager.fileExists(atPath: self.absoluteURL(toPath).path) {
-                completionHandler?(self.throwError(toPath, code: URLError.cannotWriteToFile as FoundationErrorEnum))
-                return
-            }
-            do {
-                try self.opFileManager.copyItem(at: self.absoluteURL(path), to: self.absoluteURL(toPath))
-                completionHandler?(nil)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                })
-            } catch let e as NSError {
-                completionHandler?(e)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                })
-            }
-        }
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
-    }
-    
-    @discardableResult
-    open func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.remove(path: path)
-        operation_queue.async {
-            do {
-                try self.opFileManager.removeItem(at: self.absoluteURL(path))
-                completionHandler?(nil)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                })
-            } catch let e as NSError {
-                completionHandler?(e)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderFailed(self, operation: opType)
-                })
-            }
-        }
-        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.async {
-            do {
-                try self.opFileManager.copyItem(at: localFile, to: self.absoluteURL(toPath))
-                completionHandler?(nil)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                })
-            } catch let e as NSError {
-                completionHandler?(e)
-                DispatchQueue.main.async(execute: {
-                    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.async {
-            do {
-                try self.opFileManager.copyItem(at: self.absoluteURL(path), to: toLocalURL)
-                completionHandler?(nil)
-                DispatchQueue.main.async(execute: {
-                    self.delegate?.fileproviderSucceed(self, operation: opType)
-                })
-            } catch let e as NSError {
-                completionHandler?(e)
-                DispatchQueue.main.async(execute: {
-                    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? {
+    open func searchFiles(path: String, recursive: Bool, query: NSPredicate, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
        dispatch_queue.async {
-            let data = self.fileManager.contents(atPath: self.absoluteURL(path).path)
-            completionHandler(data, nil)
-        }
-        return nil
-    }
-    
-    @discardableResult
-    open func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
-        if length < 0 {
-            return self.contents(path: path, completionHandler: completionHandler)
-        }
-        let opType = FileOperationType.fetch(path: path)
-        dispatch_queue.async {
-            let aPath = self.absoluteURL(path).path
-            guard self.fileManager.fileExists(atPath: aPath) && !self.absoluteURL(path).fileIsDirectory else {
-                completionHandler(nil, self.throwError(path, code: URLError.cannotOpenFile as FoundationErrorEnum))
-                return
-            }
-            guard let handle = FileHandle(forReadingAtPath: aPath) else {
-                completionHandler(nil, self.throwError(path, code: URLError.cannotOpenFile as FoundationErrorEnum))
-                return
-            }
-            defer {
-                handle.closeFile()
-            }
-            handle.seek(toFileOffset: UInt64(offset))
-            let data = handle.readData(ofLength: length)
-            completionHandler(data, nil)
-            
-        }
-        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
-    }
-    
-    @discardableResult
-    open func writeContents(path: String, contents data: Data, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        let opType = FileOperationType.modify(path: path)
-        var options: Data.WritingOptions = []
-        if atomically {
-            options.insert(.atomic)
-        }
-        if overwrite {
-            options.insert(.withoutOverwriting)
-        }
-        operation_queue.async {
-            try? data.write(to: self.absoluteURL(path), options: atomically ? [.atomic] : [])
-            DispatchQueue.main.async(execute: {
-                self.delegate?.fileproviderSucceed(self, operation: opType)
-            })
-        }
-        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.absoluteURL(path), includingPropertiesForKeys: nil, options: recursive ? [] : [.skipsSubdirectoryDescendants, .skipsPackageDescendants]) { (url, e) -> Bool in
+            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)
-                    }
+                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) + "/")
+        return self.doOperation(opType, completionHandler: completionHandler)
+    }
+    
+    @discardableResult
+    open func create(file fileName: String, at atPath: String, contents data: Data?, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let fileName = fileName.trimmingCharacters(in: CharacterSet(charactersIn: "/"))
+        let path = (atPath as NSString).appendingPathComponent(fileName)
+        let opType = FileOperationType.create(path: path)
+        
+        return self.doOperation(opType, data: data, atomically: true, 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)
+
+        if !overwrite && self.fileManager.fileExists(atPath: self.url(of: toPath).path) {
+            completionHandler?(self.throwError(toPath, code: CocoaError.fileWriteFileExists as FoundationErrorEnum))
+            return nil
+        }
+        
+        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)
+        
+        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
+        }
+        
+        return self.doOperation(opType, completionHandler: completionHandler)
+    }
+    
+    @discardableResult
+    open func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let opType = FileOperationType.remove(path: 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? {
+        
+        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 {
+                switch opType {
+                case .create:
+                    if sourcePath.hasSuffix("/") {
+                        try self.opFileManager.createDirectory(at: source, withIntermediateDirectories: true, attributes: [:])
+                    } else {
+                        try data?.write(to: source, options: Data.WritingOptions.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)
+                }
+                DispatchQueue.main.async {
+                    self.delegate?.fileproviderSucceed(self, operation: opType)
+                }
+            } catch let e {
+                if successfulSecurityScopedResourceAccess {
+                    source.stopAccessingSecurityScopedResource()
+                }
+                self.dispatch_queue.async {
+                    completionHandler?(e)
+                }
+                DispatchQueue.main.async {
+                    self.delegate?.fileproviderFailed(self, operation: opType)
+                }
+            }
+        }
+        
+        if isCoorinating {
+            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(source, dest)
+            }
+        }
+        
+        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
+            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
+                self.dispatch_queue.async {
+                    completionHandler(nil, error)
+                }
+                DispatchQueue.main.async {
+                    self.delegate?.fileproviderFailed(self, operation: opType)
+                }
+            })
+        } else {
+            dispatch_queue.async {
+                operationHandler(url)
+            }
+        }
+        
+        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
+    }
+    
+    @discardableResult
+    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
+        }
+        
+        if offset == 0 && length < 0 {
+            return self.contents(path: path, completionHandler: completionHandler)
+        }
+        
+        let opType = FileOperationType.fetch(path: path)
+        let url = self.url(of: path)
+        
+        let operationHandler: (URL) -> Void = { url in
+            guard let handle = FileHandle(forReadingAtPath: url.path) else {
+                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)
+            
+            self.dispatch_queue.async {
+                completionHandler(data, nil)
+            }
+        }
+        
+        if isCoorinating {
+            let intent = NSFileAccessIntent.readingIntent(with: url, options: .withoutChanges)
+            coordinated(intents: [intent], completionHandler: operationHandler, errorHandler: { error in
+                completionHandler(nil, error)
+                DispatchQueue.main.async {
+                    self.delegate?.fileproviderFailed(self, operation: opType)
+                }
+            })
+        } else {
+            dispatch_queue.async {
+                operationHandler(url)
+            }
+        }
+        
+        return LocalOperationHandle(operationType: opType, baseURL: self.baseURL)
+    }
+    
+    @discardableResult
+    open func writeContents(path: String, contents data: Data, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+        let opType = FileOperationType.modify(path: path)
+        return self.doOperation(opType, data: data, atomically: atomically, completionHandler: completionHandler)
+    }
+    
    fileprivate var monitors = [LocalFolderMonitor]()
    
    open func registerNotifcation(path: String, eventHandler: @escaping (() -> Void)) {
        self.unregisterNotifcation(path: path)
-        let absurl = self.absoluteURL(path)
-        let isdir = (try? absurl.resourceValues(forKeys: [.isDirectoryKey]).isDirectory ?? false) ?? false
+        let dirurl = self.url(of: path)
+        let isdir = (try? dirurl.resourceValues(forKeys: [.isDirectoryKey]).isDirectory ?? false) ?? false
        if !isdir {
            return
        }
-        let monitor = LocalFolderMonitor(url: absurl) {
+        let monitor = LocalFolderMonitor(url: dirurl) {
            eventHandler()
        }
        monitor.start()
@@ -325,33 +499,95 @@ open class LocalFileProvider: FileProvider, FileProviderMonitor {
    }
    
    open func isRegisteredForNotification(path: String) -> Bool {
-        return monitors.map( { self.relativePathOf(url: $0.url) } ).contains(path)
+        return monitors.map( { self.relativePathOf(url: $0.url) } ).contains(path.trimmingCharacters(in: CharacterSet(charactersIn: "/")))
    }
    
    open func copy(with zone: NSZone? = nil) -> Any {
        let copy = LocalFileProvider(baseURL: self.baseURL!)
        copy.currentPath = self.currentPath
+        copy.isPathRelative = self.isPathRelative
+        copy.undoManager = self.undoManager
+        copy.isCoorinating = self.isCoorinating
        copy.delegate = self.delegate
        copy.fileOperationDelegate = self.fileOperationDelegate
-        copy.isPathRelative = self.isPathRelative
        return copy
    }
 }

 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 destURL, making it possible 
+     to create symbolic links to locations that do not yet exist. 
+     Also, if the final path component in url is a symbolic link, that link is not followed.
+    
+     - Parameters:
+       - path: The file path at which to create the new symbolic link. The last component of the path issued as the name of the link.
+       - destPath: 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.async {
+        operation_queue.addOperation {
            do {
-                try self.opFileManager.createSymbolicLink(at: self.absoluteURL(path), withDestinationURL: self.absoluteURL(destPath))
+                try self.opFileManager.createSymbolicLink(at: self.url(of: path), withDestinationURL: self.url(of: destPath))
                completionHandler?(nil)
-                DispatchQueue.main.async(execute: {
+                DispatchQueue.main.async {
                    self.delegate?.fileproviderSucceed(self, operation: .link(link: path, target: destPath))
-                })
-            } catch let e as NSError {
+                }
+            } catch let e {
                completionHandler?(e)
-                DispatchQueue.main.async(execute: {
+                DispatchQueue.main.async {
                    self.delegate?.fileproviderFailed(self, operation: .link(link: path, target: destPath))
-                })
+                }
+            }
+        }
+    }
+    
+    /// 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 {
+                let destPath = try self.opFileManager.destinationOfSymbolicLink(atPath: self.url(of: path).path)
+                let destUrl = URL(fileURLWithPath: destPath)
+                completionHandler(destUrl, nil)
+            } catch let e{
+                completionHandler(nil, e)
+            }
+        }
+    }
+}
+
+internal extension LocalFileProvider {
+    func coordinated(intents: [NSFileAccessIntent], completionHandler: @escaping (_ url: 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
+            }
+            completionHandler(intents[0].url)
+        }
+    }
+    
+    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
+            }
+            let newSource: URL = intents[0].url
+            let newDest: URL? = intents.count > 1 ? intents[1].url : nil
+            if moving, let newDest = newDest {
+                coordinator.item(at: newSource, willMoveTo: newDest)
+            }
+            completionHandler(newSource, newDest)
+            if moving, let newDest = newDest {
+                coordinator.item(at: newSource, didMoveTo: newDest)
            }
        }
    }
@@ -8,52 +8,83 @@

 import Foundation

+/// Containts path, url and attributes of a local file or resource.
 public final class LocalFileObject: FileObject {
-    internal init(absoluteURL: URL, name: String, path: String) {
-        super.init(absoluteURL: absoluteURL, name: name, path: path)
+    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?) {
-        let fileURL: URL
-        if let relativeURL = relativeURL {
-            fileURL = relativeURL.appendingPathComponent(path)
-        } else {
-            fileURL = URL(fileURLWithPath: path)
+        var fileURL: URL?
+        var rpath = path.replacingOccurrences(of: relativeURL?.path ?? "", with: "", options: .anchored)
+        if relativeURL != nil && rpath.hasPrefix("/") {
+            rpath.remove(at: rpath.startIndex)
        }
-        do {
-            let values = try fileURL.resourceValues(forKeys: [.nameKey, .fileSizeKey, .fileAllocatedSizeKey, .creationDateKey, .contentModificationDateKey, .fileResourceTypeKey, .isHiddenKey, .isWritableKey])
-            self.init(absoluteURL: fileURL, name: values.name ?? fileURL.lastPathComponent, path: path)
-            for (key, value) in values.allValues {
-                self.allValues[key.rawValue] = value
+        if rpath.isEmpty {
+            fileURL = 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)
            }
-        } catch {
+        }
+        if let fileURL = fileURL {
+            self.init(fileWithURL: fileURL)
+        } else {
            return nil
        }
    }
    
+    /// 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])
-            self.init(absoluteURL: fileURL, name: values.name ?? fileURL.lastPathComponent, path: fileURL.path)
+            let values = try fileURL.resourceValues(forKeys: [.nameKey, .fileSizeKey, .fileAllocatedSizeKey, .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[.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)
@@ -185,12 +216,13 @@ internal class LocalFileProviderManagerDelegate: NSObject, FileManagerDelegate {
    }
 }

+/// Local operation handling is limited. Please don't use as much as possible.
 open class LocalOperationHandle: OperationHandle {
    public let baseURL: URL
    public let operationType: FileOperationType
    
    init (operationType: FileOperationType, baseURL: URL?) {
-        self.baseURL = baseURL ?? LocalFileProvider.defaultBaseURL()
+        self.baseURL = baseURL ?? URL(fileURLWithPath: "/")
        self.operationType = operationType
    }
    
@@ -283,6 +315,18 @@ open class LocalOperationHandle: OperationHandle {
    }
 }

+class UndoBox: NSObject {
+    weak var provider: FileProvideUndoable?
+    let operation: FileOperationType
+    let undoOperation: FileOperationType
+    
+    init(provider: FileProvideUndoable, operation: FileOperationType, undoOperation: FileOperationType) {
+        self.provider = provider
+        self.operation = operation
+        self.undoOperation = undoOperation
+    }
+}
+
 internal extension URL {
    var fileIsDirectory: Bool {
        return (try? self.resourceValues(forKeys: [.isDirectoryKey]))?.isDirectory ?? false
@@ -10,29 +10,39 @@
 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: NSObject,  FileProviderBasicRemote {
-    open static let type: String = "OneDrive"
-    open let isPathRelative: Bool = true
+/**
+ 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 isPathRelative: Bool
    open let baseURL: URL?
+    /// OneDrive server url, equals with unwrapped `baseURL`
+    open var serverURL: URL { return baseURL! }
+    /// 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 driveURL: URL {
-        return URL(string: "/drive/root:/", relativeTo: baseURL)!
+        return URL(string: "/drive/\(drive):/", relativeTo: baseURL)!
    }
-    open var currentPath: String = ""
+    open var currentPath: String
    
-    open var dispatch_queue: DispatchQueue {
+    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 = false
-    public var validatingCache: Bool = true
+    public var useCache: Bool
+    public var validatingCache: Bool
   
    fileprivate var _session: URLSession?
    fileprivate var sessionDelegate: SessionDelegate?
@@ -49,17 +59,41 @@ open class OneDriveFileProvider: NSObject,  FileProviderBasicRemote {
        return _session!
    }
    
-    public init? (baseURL: URL?, drive: String = "root", credential: URLCredential?, cache: URLCache? = nil) {
-        self.baseURL = baseURL ?? URL(string: "https://api.onedrive.com")
+    /**
+     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 ?? URL(string: "https://api.onedrive.com/")!
+        self.baseURL = baseURL.path.hasSuffix("/") ? baseURL : baseURL.appendingPathComponent("")
        self.drive = drive
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(OneDriveFileProvider.type)", attributes: DispatchQueue.Attributes.concurrent)
-        //let url = baseURL.uw_absoluteString
-        self.credential = credential
+        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: .concurrent)
+        operation_queue = OperationQueue()
+        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
    }
    
    deinit {
-        _session?.invalidateAndCancel()
+        if fileProviderCancelTasksOnInvalidating {
+            _session?.invalidateAndCancel()
+        } else {
+            _session?.finishTasksAndInvalidate()
+        }
    }
    
    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
@@ -74,16 +108,16 @@ open class OneDriveFileProvider: NSObject,  FileProviderBasicRemote {
        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 serverError: 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 = self.mapToFileObject(json) {
+                serverError = 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)
+            completionHandler(fileObject, serverError ?? error)
        }) 
        task.resume()
    }
@@ -105,31 +139,58 @@ open class OneDriveFileProvider: NSObject,  FileProviderBasicRemote {
        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 = self.findNameQuery(query, key: "name") as? String ?? self.findNameQuery(query, key: nil) as? String
+        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 isReachable(completionHandler: @escaping (Bool) -> Void) {
+        let url = URL(string: "/drive/root", relativeTo: baseURL)!
+        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 {
    
    
-    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? {
+    open 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)
    }
    
@@ -162,19 +223,19 @@ extension OneDriveFileProvider: FileProviderOperations {
            request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
        }
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
-            var dbError: FileProviderOneDriveError?
+            var serverError: 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))
+                 serverError = FileProviderOneDriveError(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? {
        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
@@ -182,7 +243,7 @@ extension OneDriveFileProvider: 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
@@ -195,8 +256,8 @@ extension OneDriveFileProvider: FileProviderOperations {
            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)
+                let serverError : FileProviderOneDriveError? = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: errorData ?? Data(), encoding: .utf8)) : nil
+                completionHandler?(serverError ?? error)
                return
            }
            do {
@@ -213,31 +274,38 @@ extension OneDriveFileProvider: FileProviderOperations {
 }

 extension OneDriveFileProvider: 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: 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)", forHTTPHeaderField: "Range")
+            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?
+            var serverError: 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))
+                serverError = FileProviderOneDriveError(code: code, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8))
            }
-            let filedata = dbError ?? error == nil ? data : nil
-            completionHandler(filedata, dbError ?? error)
+            let filedata = serverError ?? error == nil ? data : nil
+            completionHandler(filedata, serverError ?? 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? {
+    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
@@ -246,16 +314,6 @@ extension OneDriveFileProvider: FileProviderReadWrite {
        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
@@ -269,16 +327,49 @@ extension OneDriveFileProvider: FileProviderReadWrite {
        NotImplemented()
    }
    
-    // TODO: Implement /copy_reference, /get_account & /get_current_account
+    /**
+     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)) {
+        let url =  URL(string: escaped(path: path) + ":/action.createLink", relativeTo: driveURL)!
+        var request = URLRequest(url: url)
+        request.httpMethod = "POST"
+        let requestDictionary: [String: AnyObject] = ["type": "view" as NSString]
+        request.httpBody = dictionaryToJSON(requestDictionary)?.data(using: .utf8)
+        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 data = data, let jsonStr = String(data: data, encoding: .utf8), let json = jsonToDictionary(jsonStr) {
+                    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 {
-    public func thumbnailOfFileSupported(path: String) -> Bool {
+    open func thumbnailOfFileSupported(path: String) -> Bool {
        return true
    }
    
-    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":
@@ -292,7 +383,7 @@ extension OneDriveFileProvider: ExtendedFileProvider {
        }
    }
    
-    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
        if let dimension = dimension {
            url = URL(string: escaped(path: path) + ":/thumbnails/0/=c\(dimension.width)x\(dimension.height)/content", relativeTo: driveURL)!
@@ -317,23 +408,23 @@ extension OneDriveFileProvider: 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: 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 serverError: 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
+                serverError = 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)
+            completionHandler(dic, keys, serverError ?? error)
        })
        task.resume()
    }
@@ -341,7 +432,7 @@ extension OneDriveFileProvider: ExtendedFileProvider {

 extension OneDriveFileProvider: FileProvider {
    open func copy(with zone: NSZone? = nil) -> Any {
-        let copy = OneDriveFileProvider(baseURL: self.baseURL, drive: self.drive, credential: self.credential, cache: self.cache)!
+        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
@@ -8,46 +8,71 @@

 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(name: String, path: String) {
-        super.init(absoluteURL: URL(string: path), name: name, path: path)
+    internal init(baseURL: URL?, name: String, path: String) {
+        var rpath = path
+        if path.hasPrefix("/") {
+            rpath.remove(at: rpath.startIndex)
+        }
+        let url = URL(string: rpath, relativeTo: baseURL) ?? URL(string: path)!
+        super.init(url: url, name: name, path: path)
    }
    
+    internal convenience init? (baseURL: URL?, drive: String, jsonStr: String) {
+        guard let json = jsonToDictionary(jsonStr) 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)
+        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.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[.mimeType] as? String ?? ""
        }
        set {
-            allValues["NSURLContentTypeKey"] = newValue
+            allValues[.mimeType] = 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[.entryTag] as? String
        }
        set {
-            allValues["NSURLEntryTagKey"] = newValue
+            allValues[.entryTag] = newValue
        }
    }
 }
@@ -74,7 +99,7 @@ internal extension OneDriveFileProvider {
                let json = jsonToDictionary(jsonStr)
                if let entries = json?["value"] as? [AnyObject] , entries.count > 0 {
                    for entry in entries {
-                        if let entry = entry as? [String: AnyObject], let file = self.mapToFileObject(entry) {
+                        if let entry = entry as? [String: AnyObject], let file = OneDriveFileObject(baseURL: self.baseURL, drive: self.drive, json: entry) {
                            files.append(file)
                        }
                    }
@@ -93,7 +118,12 @@ internal extension OneDriveFileProvider {
    }
    
    func upload_simple(_ targetPath: String, data: Data, modifiedDate: Date = Date(), overwrite: Bool, operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
-        assert(data.count < 100*1024*1024, "Maximum size of allowed size to upload is 100MB")
+        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)
@@ -115,6 +145,13 @@ internal extension OneDriveFileProvider {
    }
    
    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
+        if size > 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)
@@ -156,7 +193,7 @@ internal extension OneDriveFileProvider {
                let json = jsonToDictionary(jsonStr)
                if let entries = json?["value"] as? [AnyObject] , entries.count > 0 {
                    for entry in entries {
-                        if let entry = entry as? [String: AnyObject], let file = self.mapToFileObject(entry) {
+                        if let entry = entry as? [String: AnyObject], let file = OneDriveFileObject(baseURL: self.baseURL, drive: self.drive, json: entry) {
                            foundItem(file)
                        }
                    }
@@ -178,28 +215,6 @@ internal extension OneDriveFileProvider {
 // codebeat:enable[ARITY]

 internal extension OneDriveFileProvider {
-    func mapToFileObject(_ jsonStr: String) -> OneDriveFileObject? {
-        guard let json = jsonToDictionary(jsonStr) else { return nil }
-        return self.mapToFileObject(json)
-    }
-    
-    func mapToFileObject(_ json: [String: AnyObject]) -> OneDriveFileObject? {
-        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)
-        let fileObject = OneDriveFileObject(name: name, path: lPath)
-        if let webURL = json["webUrl"] as? String, let absolluteURL = URL(string: webURL) {
-            fileObject.absoluteURL = absolluteURL
-        }
-        fileObject.size = (json["size"] as? NSNumber)?.int64Value ?? -1
-        fileObject.modifiedDate = resolve(dateString: json["lastModifiedDateTime"] as? String ?? "")
-        fileObject.creationDate = resolve(dateString: json["createdDateTime"] as? String ?? "")
-        fileObject.type = (json["folder"] as? String) != nil ? .directory : .regular
-        fileObject.id = json["id"] as? String
-        fileObject.entryTag = json["eTag"] as? String
-        return fileObject
-    }
-    
    static let dateFormatter = DateFormatter()
    static let decimalFormatter = NumberFormatter()
    
@@ -223,72 +238,51 @@ 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)"
+            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: OneDriveFileProvider.formatshort(interval: TimeInterval(duration) / 1000))
        }
-        if let timeTakenStr = json["takenDateTime"] as? String, let timeTaken = self.resolve(dateString: timeTakenStr) {
-            keys.append("Date taken")
+        if let timeTakenStr = json["takenDateTime"] as? String, let timeTaken = resolve(dateString: 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)
    }
@@ -8,6 +8,7 @@

 import Foundation

+/// Allows to get progress or cancel an in-progress operation, for remote, `URLSession` based providers.
 open class RemoteOperationHandle: OperationHandle {
    
    internal var tasks: [Weak<URLSessionTask>]
@@ -42,7 +43,7 @@ open class RemoteOperationHandle: OperationHandle {
            if let task = $1.value as? URLSessionUploadTask {
                return $0 + task.countOfBytesExpectedToSend
            } else {
-                return $0 + ($1.value?.countOfBytesExpectedToSend ?? 0)
+                return $0 + ($1.value?.countOfBytesExpectedToReceive ?? 0)
            }
        }
    }
@@ -61,6 +62,23 @@ open class RemoteOperationHandle: OperationHandle {
    }
 }

+/// 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
+    }
+}
+
 class SessionDelegate: NSObject, URLSessionDataDelegate, URLSessionDownloadDelegate {
    
    weak var fileProvider: FileProvider?
@@ -138,67 +156,129 @@ class SessionDelegate: NSObject, URLSessionDataDelegate, URLSessionDownloadDeleg
    }
 }

-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 +299,7 @@ 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 +307,7 @@ 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"
        }
    }
 }
@@ -9,11 +9,12 @@
 import Foundation

 class SMBFileProvider: FileProvider, FileProviderMonitor {
-    open static var type: String = "Samba"
+    open class var type: String { return "SMB" }
    open var isPathRelative: Bool = true
    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?
    
@@ -23,9 +24,11 @@ class SMBFileProvider: FileProvider, FileProviderMonitor {
        guard baseURL.uw_scheme.lowercased() == "smb" else {
            return nil
        }
-        self.baseURL = baseURL
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(SMBFileProvider.type)", attributes: DispatchQueue.Attributes.concurrent)
-        //let url = baseURL.uw_absoluteString
+        self.baseURL = baseURL.appendingPathComponent("")
+        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
    }
        
@@ -41,6 +44,10 @@ 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? {
@@ -93,7 +100,7 @@ class SMBFileProvider: FileProvider, FileProviderMonitor {
        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()
    }
    
@@ -119,7 +126,7 @@ 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
@@ -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)
@@ -8,48 +8,35 @@

 import Foundation

-public final class WebDavFileObject: FileObject {
-    internal init(absoluteURL: URL, name: String, path: String) {
-        super.init(absoluteURL: absoluteURL, name: name, path: path)
-    }
-    
-    open internal(set) var contentType: String {
-        get {
-            return allValues["NSURLContentTypeKey"] as? String ?? ""
-        }
-        set {
-            allValues["NSURLContentTypeKey"] = newValue
-        }
-    }
-    
-    open internal(set) var entryTag: String? {
-        get {
-            return allValues["NSURLEntryTagKey"] as? String
-        }
-        set {
-            allValues["NSURLEntryTagKey"] = newValue
-        }
-    }
-}
-
-/// 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 WebDAVFileProvider: NSObject,  FileProviderBasicRemote {
-    open static let type: String = "WebDAV"
-    open let isPathRelative: Bool = true
+/**
+ 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 class var type: String { return "WebDAV" }
+    open let isPathRelative: Bool
    open let baseURL: URL?
-    open var currentPath: String = ""
-    public var dispatch_queue: DispatchQueue {
+    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.")
        }
    }
+    
    public weak var delegate: FileProviderDelegate?
    open let credential: URLCredential?
    open private(set) var cache: URLCache?
-    public var useCache: Bool = false
-    public var validatingCache: Bool = true
+    public var useCache: Bool
+    public var validatingCache: Bool
    
    fileprivate var _session: URLSession?
    fileprivate var sessionDelegate: SessionDelegate?
@@ -66,24 +53,41 @@ open class WebDAVFileProvider: NSObject,  FileProviderBasicRemote {
        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
-        dispatch_queue = DispatchQueue(label: "FileProvider.\(WebDAVFileProvider.type)", attributes: DispatchQueue.Attributes.concurrent)
-        //let url = baseURL.uw_absoluteString
-        self.credential = credential
+        self.baseURL = baseURL.path.hasSuffix("/") ? baseURL : baseURL.appendingPathComponent("")
+        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: .concurrent)
+        operation_queue = OperationQueue()
+        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
    }
    
    deinit {
-        _session?.invalidateAndCancel()
+        if fileProviderCancelTasksOnInvalidating {
+            _session?.invalidateAndCancel()
+        } else {
+            _session?.finishTasksAndInvalidate()
+        }
    }
    
    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
        let opType = FileOperationType.fetch(path: path)
-        let url = absoluteURL(path)
+        let url = self.url(of: path).appendingPathComponent("")
        var request = URLRequest(url: url)
        request.httpMethod = "PROPFIND"
        request.setValue("1", forHTTPHeaderField: "Depth")
@@ -93,16 +97,16 @@ open class WebDAVFileProvider: NSObject,  FileProviderBasicRemote {
        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 {
-                let xresponse = self.parseXMLResponse(data)
-                for attr in xresponse {
+                let xresponse = DavResponse.parse(xmlResponse: data, baseURL: self.baseURL)
+                for attr in xresponse where attr.href != url {
                    if attr.href.path == url.path {
                        continue
                    }
-                    fileObjects.append(self.mapToFileObject(attr))
+                    fileObjects.append(WebDavFileObject(attr))
                }
            }
            completionHandler(fileObjects, responseError ?? error)
@@ -110,7 +114,7 @@ open class WebDAVFileProvider: NSObject,  FileProviderBasicRemote {
    }
    
    open func attributesOfItem(path: String, completionHandler: @escaping ((_ attributes: FileObject?, _ error: Error?) -> Void)) {
-        let url = absoluteURL(path)
+        let url = self.url(of: path)
        var request = URLRequest(url: url)
        request.httpMethod = "PROPFIND"
        request.setValue("1", forHTTPHeaderField: "Depth")
@@ -120,12 +124,12 @@ open class WebDAVFileProvider: NSObject,  FileProviderBasicRemote {
        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 = self.parseXMLResponse(data)
+                let xresponse = DavResponse.parse(xmlResponse: data, baseURL: self.baseURL)
                if let attr = xresponse.first {
-                    completionHandler(self.mapToFileObject(attr), responseError ?? error)
+                    completionHandler(WebDavFileObject(attr), responseError ?? error)
                    return
                }
            }
@@ -150,7 +154,7 @@ open class WebDAVFileProvider: NSObject,  FileProviderBasicRemote {
            var totalSize: Int64 = -1
            var usedSize: Int64 = 0
            if let data = data {
-                let xresponse = self.parseXMLResponse(data)
+                let xresponse = DavResponse.parse(xmlResponse: data, baseURL: self.baseURL)
                if let attr = xresponse.first {
                    totalSize = Int64(attr.prop["quota-available-bytes"] ?? "") ?? -1
                    usedSize = Int64(attr.prop["quota-used-bytes"] ?? "") ?? 0
@@ -160,23 +164,68 @@ open class WebDAVFileProvider: NSObject,  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 = absoluteURL((atPath as NSString).appendingPathComponent(folderName) + "/")
+        let url = self.url(of: atPath).appendingPathComponent(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)
@@ -187,18 +236,18 @@ extension WebDAVFileProvider: FileProviderOperations {
    }
    
    @discardableResult
-    public func create(file fileName: String, at path: String, contents data: Data?, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open 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 = absoluteURL(path).appendingPathComponent(fileName)
+        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)
+                responseError = FileProviderWebDavError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8), url: url)
            }
            completionHandler?(responseError ?? error)
            self.delegateNotify(opType, error: responseError ?? error)
@@ -209,7 +258,7 @@ extension WebDAVFileProvider: FileProviderOperations {
    }
    
    @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
@@ -218,7 +267,7 @@ 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
@@ -227,7 +276,7 @@ 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
@@ -236,10 +285,11 @@ extension WebDAVFileProvider: FileProviderOperations {
    }
    
    func doOperation(operation opType: FileOperationType, overwrite: Bool? = nil, completionHandler: SimpleCompletionHandler) -> OperationHandle?  {
-        let sourceURL = absoluteURL(opType.source!)
+        let source = opType.source!
+        let sourceURL = self.url(of: source)
        var request = URLRequest(url: sourceURL)
        if let dest = opType.destination {
-            request.setValue(absoluteURL(dest).absoluteString, forHTTPHeaderField: "Destination")
+            request.setValue(url(of:dest).absoluteString, forHTTPHeaderField: "Destination")
        }
        switch opType {
        case .copy:
@@ -259,12 +309,13 @@ 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 = self.parseXMLResponse(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)
                    }
                }
            }
@@ -280,19 +331,21 @@ 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? {
        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
        }
-        let url = absoluteURL(toPath)
+        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
            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: toPath, errorDescription: String(data: data ?? Data(), encoding: .utf8), url: url)
            }
            completionHandler?(responseError ?? error)
            self.delegateNotify(opType, error: responseError ?? error)
@@ -303,17 +356,17 @@ extension WebDAVFileProvider: FileProviderOperations {
    }
    
    @discardableResult
-    public func copyItem(path: String, toLocalURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
+    open func copyItem(path: String, toLocalURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.copy(source: path, destination: toLocalURL.absoluteString)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
        }
-        let url = absoluteURL(path)
+        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)
+                responseError = FileProviderWebDavError(code: rCode, path: path, errorDescription: nil, url: url)
            }
            if let sourceFileURL = sourceFileURL {
                do {
@@ -334,13 +387,20 @@ 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 = absoluteURL(path)
+        let url = self.url(of: path)
        var request = URLRequest(url: url)
        request.httpMethod = "GET"
        if length > 0 {
-            request.setValue("bytes=\(offset)-\(offset + length)", forHTTPHeaderField: "Range")
+            request.setValue("bytes=\(offset)-\(offset + length - 1)", forHTTPHeaderField: "Range")
        } else if offset > 0 && length < 0 {
            request.setValue("bytes=\(offset)-", forHTTPHeaderField: "Range")
        }
@@ -348,7 +408,7 @@ extension WebDAVFileProvider: FileProviderReadWrite {
        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)
+                responseError = FileProviderWebDavError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8), url: url)
            }
            completionHandler(data, responseError ?? error)
        })
@@ -356,13 +416,13 @@ extension WebDAVFileProvider: FileProviderReadWrite {
    }
    
    @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
        }
        // FIXME: lock destination before writing process
-        let url = atomically ? absoluteURL(path).appendingPathExtension("tmp") : absoluteURL(path)
+        let url = atomically ? self.url(of: path).appendingPathExtension("tmp") : self.url(of: path)
        var request = URLRequest(url: url)
        request.httpMethod = "PUT"
        if !overwrite {
@@ -371,7 +431,7 @@ extension WebDAVFileProvider: FileProviderReadWrite {
        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: self.absoluteURL(path))
+                responseError = FileProviderWebDavError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8), url: self.url(of: path))
            }
            defer {
                self.delegateNotify(opType, error: responseError ?? error)
@@ -389,38 +449,7 @@ extension WebDAVFileProvider: FileProviderReadWrite {
        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 = absoluteURL(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 = self.parseXMLResponse(data)
-                var fileObjects = [WebDavFileObject]()
-                for attr in xresponse {
-                    let path = attr.href.path
-                    if !((path as NSString).lastPathComponent.contains(query)) {
-                        continue
-                    }
-                    let fileObject = self.mapToFileObject(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.
@@ -428,10 +457,11 @@ 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
 }

@@ -450,37 +480,34 @@ extension WebDAVFileProvider: FileProvider {
 // MARK: WEBDAV XML response implementation

 internal extension WebDAVFileProvider {
-    struct DavResponse {
-        let href: URL
-        let hrefString: String
-        let status: Int?
-        let prop: [String: String]
+    fileprivate 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)
+            }
+        })
    }
+}
+
+struct DavResponse {
+    let href: URL
+    let hrefString: String
+    let status: Int?
+    let prop: [String: String]
    
-    fileprivate func parseXMLResponse(_ response: Data) -> [DavResponse] {
-        var result = [DavResponse]()
-        do {
-            let xml = try AEXMLDocument(xml: response)
-            var rootnode = xml.root
-            var responsetag = "response"
-            for node in rootnode.all ?? [] where node.name.lowercased().hasSuffix("multistatus") {
-                rootnode = node
+    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
            }
-            for node in rootnode.children where node.name.lowercased().hasSuffix("response") {
-                responsetag = node.name
-                break
-            }
-            for responseNode in rootnode[responsetag].all ?? [] {
-                if let davResponse = mapNodeToDavResponse(responseNode) {
-                    result.append(davResponse)
-                }
-            }
-        } catch _ { 
        }
-        return result
-    }
-    
-    fileprivate func mapNodeToDavResponse(_ node: AEXMLElement) -> DavResponse? {
+        
+        // find node names with namespace
        var hreftag = "href"
        var statustag = "status"
        var propstattag = "propstat"
@@ -495,71 +522,116 @@ internal extension WebDAVFileProvider {
                propstattag = node.name
            }
        }
-        let href = node[hreftag].value
-        if let href = href, let hrefURL = URL(string: href) {
-            var status: Int?
-            let statusDesc = (node[statustag].string).components(separatedBy: " ")
-            if statusDesc.count > 2 {
-                status = Int(statusDesc[1])
+        
+        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
+        
+        guard let href = hrefURL?.standardized else { return nil }
+        
+        // reading status and properties
+        var status: Int?
+        let statusDesc = (node[statustag].string).components(separatedBy: " ")
+        if statusDesc.count > 2 {
+            status = Int(statusDesc[1])
+        }
+        var propDic = [String: String]()
+        let propStatNode = node[propstattag]
+        for node in propStatNode.children where node.name.lowercased().hasSuffix("status"){
+            statustag = node.name
+            break
+        }
+        let statusDesc2 = (propStatNode[statustag].string).components(separatedBy: " ")
+        if statusDesc2.count > 2 {
+            status = Int(statusDesc2[1])
+        }
+        var proptag = "prop"
+        for tnode in propStatNode.children where tnode.name.lowercased().hasSuffix("prop") {
+            proptag = tnode.name
+            break
+        }
+        for propItemNode in propStatNode[proptag].children {
+            propDic[propItemNode.name.components(separatedBy: ":").last!.lowercased()] = propItemNode.value
+            if propItemNode.name.hasSuffix("resourcetype") && propItemNode.xml.contains("collection") {
+                propDic["getcontenttype"] = "httpd/unix-directory"
            }
-            var propDic = [String: String]()
-            let propStatNode = node[propstattag]
-            for node in propStatNode.children where node.name.lowercased().hasSuffix("status"){
-                statustag = node.name
+        }
+        self.href = href
+        self.hrefString = hrefString
+        self.status = status
+        self.prop = propDic
+    }
+    
+    static func parse(xmlResponse: Data, baseURL: URL?) -> [DavResponse] {
+        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
+            }
+            for node in rootnode.children where node.name.lowercased().hasSuffix("response") {
+                responsetag = node.name
                break
            }
-            let statusDesc2 = (propStatNode[statustag].string).components(separatedBy: " ")
-            if statusDesc2.count > 2 {
-                status = Int(statusDesc2[1])
-            }
-            var proptag = "prop"
-            for tnode in propStatNode.children where tnode.name.lowercased().hasSuffix("prop") {
-                proptag = tnode.name
-                break
-            }
-            for propItemNode in propStatNode[proptag].children {
-                propDic[propItemNode.name.components(separatedBy: ":").last!.lowercased()] = propItemNode.value
-                if propItemNode.name.hasSuffix("resourcetype") && propItemNode.xml.contains("collection") {
-                    propDic["getcontenttype"] = "httpd/unix-directory"
+            for responseNode in rootnode[responsetag].all ?? [] {
+                if let davResponse = DavResponse(responseNode, baseURL: baseURL) {
+                    result.append(davResponse)
                }
            }
-            return DavResponse(href: hrefURL, hrefString: href, status: status, prop: propDic)
+        } catch _ {
        }
-        return nil
-    }
-    
-    fileprivate func mapToFileObject(_ davResponse: DavResponse) -> WebDavFileObject {
-        var href = davResponse.href
-        if href.baseURL == nil {
-            href = absoluteURL(href.path)
-        }
-        let name = davResponse.prop["displayname"] ?? (davResponse.hrefString.removingPercentEncoding! as NSString).lastPathComponent
-        let fileObject = WebDavFileObject(absoluteURL: href, name: name, path: href.path)
-        fileObject.size = Int64(davResponse.prop["getcontentlength"] ?? "-1") ?? NSURLSessionTransferSizeUnknown
-        fileObject.creationDate = self.resolve(dateString: davResponse.prop["creationdate"] ?? "")
-        fileObject.modifiedDate = self.resolve(dateString: davResponse.prop["getlastmodified"] ?? "")
-        fileObject.contentType = davResponse.prop["getcontenttype"] ?? "octet/stream"
-        fileObject.type = fileObject.contentType == "httpd/unix-directory" ? .directory : .regular
-        fileObject.entryTag = davResponse.prop["getetag"]
-        return fileObject
-    }
-    
-    fileprivate 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)
-            }
-        })
+        return result
    }
 }

-public struct FileProviderWebDavError: Error, CustomStringConvertible {
-    public let code: FileProviderHTTPErrorCode
-    public let url: URL
+/// 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 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.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"]
+    }
    
-    public var description: String {
-        return code.description
+    /// MIME type of the file.
+    open internal(set) var contentType: String {
+        get {
+            return allValues[.mimeType] as? String ?? ""
+        }
+        set {
+            allValues[.mimeType] = newValue
+        }
+    }
+    
+    /// HTTP E-Tag, can be used to mark changed files.
+    open internal(set) var entryTag: String? {
+        get {
+            return allValues[.entryTag] as? String
+        }
+        set {
+            allValues[.entryTag] = newValue
+        }
    }
 }
+
+/// 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
+}
Author	SHA1	Message	Date
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
Amir Abbas Mousavian	c38ee1ccd3	standardized FileObject.path property - FileObject.path now has heading slash in all scenarios - fixes #27, WebDAV fileObject.path was not relative	2017-02-01 21:23:11 +03:30
Amir Abbas Mousavian	1a44df3fd7	Refactoring, better webdav response handling - Added Dropbox copy from reference method - refactored `mapToFileObject` methods into `FileObject` initializers - fixed `requestDictionary` type to `[String: AnyObject]`	2017-02-01 14:08:28 +03:30
Amir Abbas Mousavian	eff3725680	Added release version badge	2017-02-01 00:21:48 +03:30
Amir Abbas Mousavian	9368f636d3	Added carthage badge	2017-01-31 23:53:06 +03:30
Amir Abbas Mousavian	3f2fda638f	bugfix: path in `LocalFileObject` is not relative	2017-01-31 23:12:29 +03:30
Amir Abbas Mousavian	6737f98978	Updated travis.yml	2017-01-31 19:07:11 +03:30
Amir Abbas Mousavian	3e55cc60f7	Replaced absoluteURL with relative url (resolved #27 ), improving performance. - renamed `DropboxFileProvider.copyItem(path:toRemoteURL:) ` to `DropboxFileProvider.copyItem(remoteURL:toPath:)` due to logic	2017-01-31 17:19:45 +03:30
Alek Slater	d7ae709cf7	contentURL was missing the trailing slash causing it to fail for all contentURL calls with the dropbox api (#26 )	2017-01-31 13:05:20 +03:30
Amir Abbas Mousavian	4f6e3c7bd5	Uncommented CloudFileProvider decription	2017-01-31 02:11:28 +03:30
Amir Abbas Mousavian	b121fe6182	rectified macOS and tvOS version check	2017-01-31 01:42:03 +03:30
Amir Abbas Mousavian	29b7f720f5	Added iCloud provider change monitor and CloudOperationHandle - fixed copyItem functions for local interoperability	2017-01-31 01:35:38 +03:30
Amir Abbas Mousavian	067e14b76f	Added `CloudFileProvider` and coordination to `LocalFileProvider` - changed `operation_queue` type to `OperationQueue` - added `LocalFileProvider.init(sharedContainerId:)` - added `destination(ofSymbolicLink:)` to LocalFileProvider - added expirationDate to `temporaryLink(to:)` methods - known issue: `CloudFileProvider` monitoring is not implemented - known issue: `CloudFileProvider` copy from local and to local works imperfect	2017-01-30 18:51:06 +03:30
Amir Abbas Mousavian	09e39ada82	Resolved issue #24 , off-by-one bug in `Range` header	2017-01-30 18:37:25 +03:30
Amir Abbas	6889b302b7	Removed CloudProvider due to incompleteness	2017-01-27 02:47:11 +03:30
Amir Abbas	96ce12f226	Added iCloud Drive provider `CloudFileProvider` - Refactored initializers - Replaced `NSSearchPathForDirectoriesInDomains` with `FileManager.urls(for:In:)`	2017-01-27 02:13:51 +03:30
Amir Abbas	091fd14a88	OneDrive drive name bug fix. Added sorting method to `[FileObject]` array. - now return `Error` for uploading a file with size higher than limit in OneDrive / Dropbox instead of asserting	2017-01-25 16:04:16 +03:30