Version 2.6.5

This problem arose after 6611ec8 commit. The root cause is linked to
this condition: `0 == layoutAdapter.offsetFromMostExpandedAnchor` at
line 589 in the method `Core.shouldScrollViewHandleTouch(_:point:velocity:)`.

If the value of `layoutAdapter.offsetFromMostExpandedAnchor` has a
floating point error, the condition evaluates to false. As a result,
the panel moves even when the tracking scroll view is intended to
scroll.

This problem may not occur if there is no floating point error.

.github/workflows/ci.yml

@@ -51,10 +51,10 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: "16.1"
-            xcode: "14.1"
+          - os: "16.4"
+            xcode: "14.3.1"
             sim: "iPhone 14 Pro"
-            runsOn: macos-12
+            runsOn: macos-13
           - os: "15.5"
             xcode: "13.4.1"
             sim: "iPhone 13 Pro"

FloatingPanel.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
 
   s.name                = "FloatingPanel"
-  s.version             = "2.6.3"
+  s.version             = "2.6.5"
   s.summary             = "FloatingPanel is a clean and easy-to-use UI component of a floating panel interface."
   s.description         = <<-DESC
 FloatingPanel is a clean and easy-to-use UI component for a new interface introduced in Apple Maps, Shortcuts and Stocks app.

FloatingPanel.xcodeproj/project.pbxproj

@@ -25,7 +25,7 @@
 		549E944522CF295D0050AECF /* StateTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 549E944422CF295D0050AECF /* StateTests.swift */; };
 		54A6B6B122968B530077F348 /* CoreTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54A6B6B022968B530077F348 /* CoreTests.swift */; };
 		54A6B6B82296A8520077F348 /* SurfaceViewTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54A6B6B72296A8520077F348 /* SurfaceViewTests.swift */; };
-		54ABD7AF216CCFF7002E6C13 /* Logger.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54ABD7AE216CCFF7002E6C13 /* Logger.swift */; };
+		54ABD7AF216CCFF7002E6C13 /* Logging.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54ABD7AE216CCFF7002E6C13 /* Logging.swift */; };
 		54CDC5D3215B6D5A007D205C /* SurfaceView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CDC5D2215B6D5A007D205C /* SurfaceView.swift */; };
 		54CDC5D5215B6D8D007D205C /* BackdropView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CDC5D4215B6D8D007D205C /* BackdropView.swift */; };
 		54CFBFC3215CD045006B5735 /* Layout.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CFBFC2215CD045006B5735 /* Layout.swift */; };
@@ -67,7 +67,7 @@
 		549E944422CF295D0050AECF /* StateTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StateTests.swift; sourceTree = "<group>"; };
 		54A6B6B022968B530077F348 /* CoreTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CoreTests.swift; sourceTree = "<group>"; };
 		54A6B6B72296A8520077F348 /* SurfaceViewTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SurfaceViewTests.swift; sourceTree = "<group>"; };
-		54ABD7AE216CCFF7002E6C13 /* Logger.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Logger.swift; sourceTree = "<group>"; };
+		54ABD7AE216CCFF7002E6C13 /* Logging.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Logging.swift; sourceTree = "<group>"; };
 		54CDC5D2215B6D5A007D205C /* SurfaceView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SurfaceView.swift; sourceTree = "<group>"; };
 		54CDC5D4215B6D8D007D205C /* BackdropView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BackdropView.swift; sourceTree = "<group>"; };
 		54CFBFC2215CD045006B5735 /* Layout.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Layout.swift; sourceTree = "<group>"; };
@@ -133,7 +133,7 @@
 				545DBA2A2152383100CA77B8 /* GrabberView.swift */,
 				54352E9521A51A2500CBCA08 /* Transitioning.swift */,
 				54DBA3DB262E938500D75969 /* Extensions.swift */,
-				54ABD7AE216CCFF7002E6C13 /* Logger.swift */,
+				54ABD7AE216CCFF7002E6C13 /* Logging.swift */,
 				545DB9C42151169500CA77B8 /* FloatingPanel.h */,
 				545DB9C52151169500CA77B8 /* Info.plist */,
 				54E3992627141F5100A8F9ED /* FloatingPanel.docc */,
@@ -282,7 +282,7 @@
 				54CDC5D5215B6D8D007D205C /* BackdropView.swift in Sources */,
 				54352E9821A521CA00CBCA08 /* PassthroughView.swift in Sources */,
 				54CFBFC5215CD09C006B5735 /* Core.swift in Sources */,
-				54ABD7AF216CCFF7002E6C13 /* Logger.swift in Sources */,
+				54ABD7AF216CCFF7002E6C13 /* Logging.swift in Sources */,
 				545DB9E021511AC100CA77B8 /* Controller.swift in Sources */,
 				54DBA3DC262E938500D75969 /* Extensions.swift in Sources */,
 				5450EEE421646DF500135936 /* Behavior.swift in Sources */,

README.md

@@ -9,7 +9,7 @@
 FloatingPanel is a simple and easy-to-use UI component designed for a user interface featured in Apple Maps, Shortcuts and Stocks app.
 The user interface displays related content and utilities alongside the main content.
 
-Please see also [the API reference](https://floatingpanel.github.io/2.6.3/documentation/floatingpanel/) for more details.
+Please see also [the API reference](https://floatingpanel.github.io/2.6.5/documentation/floatingpanel/) for more details.
 
 ![Maps](https://github.com/SCENEE/FloatingPanel/blob/master/assets/maps.gif)
 ![Stocks](https://github.com/SCENEE/FloatingPanel/blob/master/assets/stocks.gif)

Sources/Controller.swift

@@ -1,6 +1,7 @@
 // Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
+import os.log
 
 /// A set of methods implemented by the delegate of a panel controller allows the adopting delegate to respond to
 /// messages from the FloatingPanelController class and thus respond to, and in some affect, operations such as
@@ -167,7 +168,8 @@ open class FloatingPanelController: UIViewController {
         set {
             _layout = newValue
             if let parent = parent, let layout = newValue as? UIViewController, layout == parent {
-                log.warning("A memory leak will occur by a retain cycle because \(self) owns the parent view controller(\(parent)) as the layout object. Don't let the parent adopt FloatingPanelLayout.")
+                let log = "Warning: A memory leak occurs due to a retain cycle, as \(self) owns the parent view controller(\(parent)) as its layout object. Don't allow the parent to adopt FloatingPanelLayout."
+                os_log(msg, log: sysLog, type: .error, log)
             }
         }
     }
@@ -179,7 +181,8 @@ open class FloatingPanelController: UIViewController {
         set {
             _behavior = newValue
             if let parent = parent, let behavior = newValue as? UIViewController, behavior == parent {
-                log.warning("A memory leak will occur by a retain cycle because \(self) owns the parent view controller(\(parent)) as the behavior object. Don't let the parent adopt FloatingPanelBehavior.")
+                let log = "Warning: A memory leak occurs due to a retain cycle, as \(self) owns the parent view controller(\(parent)) as its behavior object. Don't allow the parent to adopt FloatingPanelBehavior."
+                os_log(msg, log: sysLog, type: .error, log)
             }
         }
     }
@@ -375,7 +378,7 @@ open class FloatingPanelController: UIViewController {
             preSafeAreaInsets != safeAreaInsets
             else { return }
 
-        log.debug("Update safeAreaInsets", safeAreaInsets)
+        os_log(msg, log: devLog, type: .debug, "Update safeAreaInsets = \(safeAreaInsets)")
 
         // Prevent an infinite loop on iOS 10: setUpLayout() -> viewDidLayoutSubviews() -> setUpLayout()
         preSafeAreaInsets = safeAreaInsets
@@ -482,7 +485,7 @@ open class FloatingPanelController: UIViewController {
     @objc(addPanelToParent:at:animated:completion:)
     public func addPanel(toParent parent: UIViewController, at viewIndex: Int = -1, animated: Bool = false, completion: (() -> Void)? = nil) {
         guard self.parent == nil else {
-            log.warning("Already added to a parent(\(parent))")
+            os_log(msg, log: sysLog, type: .error, "Warning: already added to a parent(\(parent))")
             return
         }
         assert((parent is UINavigationController) == false, "UINavigationController displays only one child view controller at a time.")

Sources/Core.swift

@@ -1,6 +1,7 @@
 // Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
+import os.log
 
 ///
 /// The presentation model of FloatingPanel
@@ -35,7 +36,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
     private(set) var state: FloatingPanelState = .hidden {
         didSet {
-            log.debug("state changed: \(oldValue) -> \(state)")
+            os_log(msg, log: devLog, type: .debug, "state changed: \(oldValue) -> \(state)")
             if let vc = ownerVC {
                 vc.delegate?.floatingPanelDidChangeState?(vc)
             }
@@ -66,6 +67,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     private var stopScrollDeceleration: Bool = false
     private var scrollBounce = false
     private var scrollIndictorVisible = false
+    private var scrollBounceThreshold: CGFloat = -30.0
 
     // MARK: - Interface
 
@@ -126,7 +128,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         if animated {
             let updateScrollView: () -> Void = { [weak self] in
                 guard let self = self else { return }
-                if self.state == self.layoutAdapter.mostExpandedState, abs(self.layoutAdapter.offsetFromMostExpandedAnchor) <= 1.0 {
+                if self.state == self.layoutAdapter.mostExpandedState, 0 == self.layoutAdapter.offsetFromMostExpandedAnchor {
                     self.unlockScrollView()
                 } else {
                     self.lockScrollView()
@@ -162,7 +164,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                 self.updateLayout(to: to)
 
                 if shouldDoubleLayout {
-                    log.info("Lay out the surface again to modify an intrinsic size error according to UIStackView")
+                    os_log(msg, log: sysLog, type: .info, "Lay out the surface again to modify an intrinsic size error according to UIStackView")
                     self.updateLayout(to: to)
                 }
             }
@@ -231,7 +233,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 
     func getBackdropAlpha(at cur: CGFloat, with translation: CGFloat) -> CGFloat {
-        /* log.debug("currentY: \(currentY) translation: \(translation)") */
+        /* os_log(msg, log: devLog, type: .debug, "currentY: \(currentY) translation: \(translation)") */
         let forwardY = (translation >= 0)
 
         let segment = layoutAdapter.segment(at: cur, forward: forwardY)
@@ -264,7 +266,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
         guard gestureRecognizer == panGestureRecognizer else { return false }
 
-        /* log.debug("shouldRecognizeSimultaneouslyWith", otherGestureRecognizer) */
+        /* os_log(msg, log: devLog, type: .debug, "shouldRecognizeSimultaneouslyWith", otherGestureRecognizer) */
 
         switch otherGestureRecognizer {
         case is FloatingPanelPanGestureRecognizer:
@@ -337,7 +339,10 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                     if surfaceView.grabberAreaContains(gestureRecognizer.location(in: surfaceView)) {
                         return false
                     }
-                    return allowScrollPanGesture(for: scrollView)
+                    guard state == layoutAdapter.mostExpandedState else { return false }
+                    // The condition where offset > 0 must not be included here. Because it will stop recognizing
+                    // the panel pan gesture if a user starts scrolling content from an offset greater than 0.
+                    return allowScrollPanGesture(of: scrollView) { offset in offset <= scrollBounceThreshold  }
                 default:
                     return false
                 }
@@ -388,15 +393,16 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             let velocity = value(of: panGesture.velocity(in: panGesture.view))
             let location = panGesture.location(in: surfaceView)
 
-            let insideMostExpandedAnchor = 0 > layoutAdapter.offsetFromMostExpandedAnchor + (1.0 / surfaceView.fp_displayScale)
+            let insideMostExpandedAnchor = 0 > layoutAdapter.offsetFromMostExpandedAnchor
 
-            log.debug("""
+            os_log(msg, log: devLog, type: .debug, """
                 scroll gesture(\(state):\(panGesture.state)) -- \
                 inside expanded anchor = \(insideMostExpandedAnchor), \
                 interactionInProgress = \(interactionInProgress), \
                 scroll offset = \(value(of: scrollView.contentOffset)), \
                 location = \(value(of: location)), velocity = \(velocity)
-                """)
+                """
+            )
 
             let offsetDiff = value(of: scrollView.contentOffset - contentOffsetForPinning(of: scrollView))
 
@@ -404,7 +410,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                 // Scroll offset pinning
                 if state == layoutAdapter.mostExpandedState {
                     if interactionInProgress {
-                        log.debug("settle offset --", value(of: initialScrollOffset))
+                        os_log(msg, log: devLog, type: .debug, "settle offset -- \(value(of: initialScrollOffset))")
                         stopScrolling(at: initialScrollOffset)
                     } else {
                         if surfaceView.grabberAreaContains(location) {
@@ -456,21 +462,24 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                     }
                 } else {
                     if state == layoutAdapter.mostExpandedState {
+                        let allowScroll = allowScrollPanGesture(of: scrollView) { offset in
+                            offset <= scrollBounceThreshold || 0 < offset
+                        }
                         switch layoutAdapter.position {
                         case .top, .left:
-                            if velocity < 0, !allowScrollPanGesture(for: scrollView) {
+                            if velocity < 0, !allowScroll {
                                 lockScrollView(strict: true)
                             }
-                            if velocity > 0, allowScrollPanGesture(for: scrollView) {
+                            if velocity > 0, allowScroll {
                                 unlockScrollView()
                             }
                         case .bottom, .right:
                             // Hide a scroll indicator just before starting an interaction by swiping a panel down.
-                            if velocity > 0, !allowScrollPanGesture(for: scrollView) {
+                            if velocity > 0, !allowScroll {
                                 lockScrollView(strict: true)
                             }
                             // Show a scroll indicator when an animation is interrupted at the top and content is scrolled up
-                            if velocity < 0, allowScrollPanGesture(for: scrollView) {
+                            if velocity < 0, allowScroll {
                                 unlockScrollView()
                             }
                         }
@@ -486,7 +495,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             let velocity = panGesture.velocity(in: panGesture.view)
             let location = panGesture.location(in: panGesture.view)
 
-            log.debug("""
+            os_log(msg, log: devLog, type: .debug, """
                 panel gesture(\(state):\(panGesture.state)) -- \
                 translation =  \(value(of: translation)), \
                 location = \(value(of: location)), \
@@ -536,19 +545,19 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
     private func interruptAnimationIfNeeded() {
         if let animator = self.moveAnimator, animator.isRunning {
-            log.debug("the attraction animator interrupted!!!")
+            os_log(msg, log: devLog, type: .debug, "the attraction animator interrupted!!!")
             animator.stopAnimation(true)
             endAttraction(false)
         }
         if let animator = self.transitionAnimator {
             guard 0 >= layoutAdapter.offsetFromMostExpandedAnchor else { return }
-            log.debug("a panel animation(interruptible: \(animator.isInterruptible)) interrupted!!!")
+            os_log(msg, log: devLog, type: .debug, "a panel animation(interruptible: \(animator.isInterruptible)) interrupted!!!")
             if animator.isInterruptible {
                 animator.stopAnimation(false)
                 // A user can stop a panel at the nearest Y of a target position so this fine-tunes
                 // the a small gap between the presentation layer frame and model layer frame
                 // to unlock scroll view properly at finishAnimation(at:)
-                if abs(layoutAdapter.offsetFromMostExpandedAnchor) <= 1.0 {
+                if 0 == layoutAdapter.offsetFromMostExpandedAnchor {
                     layoutAdapter.surfaceLocation = layoutAdapter.surfaceLocation(for: layoutAdapter.mostExpandedState)
                 }
                 animator.finishAnimation(at: .current)
@@ -634,7 +643,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         // A user interaction does not always start from Began state of the pan gesture
         // because it can be recognized in scrolling a content in a content view controller.
         // So here just preserve the current state if needed.
-        log.debug("panningBegan -- location = \(value(of: location))")
+        os_log(msg, log: devLog, type: .debug, "panningBegan -- location = \(value(of: location))")
 
         guard let scrollView = scrollView else { return }
         if state == layoutAdapter.mostExpandedState {
@@ -647,7 +656,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 
     private func panningChange(with translation: CGPoint) {
-        log.debug("panningChange -- translation = \(value(of: translation))")
+        os_log(msg, log: devLog, type: .debug, "panningChange -- translation = \(value(of: translation))")
         let pre = value(of: layoutAdapter.surfaceLocation)
         let diff = value(of: translation - initialTranslation)
         let next = pre + diff
@@ -700,14 +709,15 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 
     private func panningEnd(with translation: CGPoint, velocity: CGPoint) {
-        log.debug("panningEnd -- translation = \(value(of: translation)), velocity = \(value(of: velocity))")
+        os_log(msg, log: devLog, type: .debug, "panningEnd -- translation = \(value(of: translation)), velocity = \(value(of: velocity))")
 
         if state == .hidden {
-            log.debug("Already hidden")
+            os_log(msg, log: devLog, type: .debug, "Already hidden")
             return
         }
 
-        stopScrollDeceleration = (0 > layoutAdapter.offsetFromMostExpandedAnchor + (1.0 / surfaceView.fp_displayScale)) // Projecting the dragging to the scroll dragging or not
+        // Determine whether the panel's dragging should be projected onto the scroll content scrolling
+        stopScrollDeceleration = 0 > layoutAdapter.offsetFromMostExpandedAnchor
         if stopScrollDeceleration {
             DispatchQueue.main.async { [weak self] in
                 guard let self = self else { return }
@@ -792,7 +802,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
     private func startInteraction(with translation: CGPoint, at location: CGPoint) {
         /* Don't lock a scroll view to show a scroll indicator after hitting the top */
-        log.debug("startInteraction  -- translation = \(value(of: translation)), location = \(value(of: location))")
+        os_log(msg, log: devLog, type: .debug, "startInteraction  -- translation = \(value(of: translation)), location = \(value(of: location))")
         guard interactionInProgress == false else { return }
 
         var offset: CGPoint = .zero
@@ -803,13 +813,14 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                 initialScrollOffset = scrollView.contentOffset
             } else {
                 let pinningOffset = contentOffsetForPinning(of: scrollView)
-
-                // `scrollView.contentOffset` can be a value in [-30, 0) at this time by `allowScrollPanGesture(for:)`.
-                // Therefore the initial scroll offset must be reset to the pinning offset. Otherwise, the following
-                // `Fit the surface bounds` logic don't working and also the scroll content offset can be invalid.
+                
+                // `initialScrollOffset` must be reset to the pinning offset because the value of `scrollView.contentOffset`,
+                // for instance, is a value in [-30, 0) on a bottom positioned panel with `allowScrollPanGesture(of:condition:)`.
+                // If it's not reset, the following logic to shift the surface frame will not work and then the scroll
+                // content offset will become an unexpected value.
                 initialScrollOffset = pinningOffset
 
-                // Fit the surface bounds to a scroll offset content by startInteraction(at:offset:)
+                // Shift the surface frame to negate the scroll content offset at startInteraction(at:offset:)
                 let offsetDiff = scrollView.contentOffset - pinningOffset
                 switch layoutAdapter.position {
                 case .top, .left:
@@ -822,7 +833,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                     }
                 }
             }
-            log.debug("initial scroll offset --", initialScrollOffset)
+            os_log(msg, log: devLog, type: .debug, "initial scroll offset -- \(initialScrollOffset)")
         }
 
         initialTranslation = translation
@@ -839,10 +850,10 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 
     private func endInteraction(for targetPosition: FloatingPanelState) {
-        log.debug("endInteraction to \(targetPosition)")
+        os_log(msg, log: devLog, type: .debug, "endInteraction to \(targetPosition)")
 
         if let scrollView = scrollView {
-            log.debug("endInteraction -- scroll offset = \(scrollView.contentOffset)")
+            os_log(msg, log: devLog, type: .debug, "endInteraction -- scroll offset = \(scrollView.contentOffset)")
         }
 
         interactionInProgress = false
@@ -870,7 +881,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 
     private func startAttraction(to targetPosition: FloatingPanelState, with velocity: CGPoint) {
-        log.debug("startAnimation to \(targetPosition) -- velocity = \(value(of: velocity))")
+        os_log(msg, log: devLog, type: .debug, "startAnimation to \(targetPosition) -- velocity = \(value(of: velocity))")
         guard let vc = ownerVC else { return }
 
         isAttracting = true
@@ -918,17 +929,17 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         }
 
         if let scrollView = scrollView {
-            log.debug("finishAnimation -- scroll offset = \(scrollView.contentOffset)")
+            os_log(msg, log: devLog, type: .debug, "finishAnimation -- scroll offset = \(scrollView.contentOffset)")
         }
 
         stopScrollDeceleration = false
 
-        log.debug("""
+        os_log(msg, log: devLog, type: .debug, """
             finishAnimation -- state = \(state) \
             surface location = \(layoutAdapter.surfaceLocation) \
             edge most position = \(layoutAdapter.surfaceLocation(for: layoutAdapter.mostExpandedState))
             """)
-        if finished, state == layoutAdapter.mostExpandedState, abs(layoutAdapter.offsetFromMostExpandedAnchor) <= 1.0 {
+        if finished, state == layoutAdapter.mostExpandedState, 0 == layoutAdapter.offsetFromMostExpandedAnchor {
             unlockScrollView()
         } else if finished, shouldLooselyLockScrollView {
             unlockScrollView()
@@ -959,7 +970,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 
     func targetPosition(from currentY: CGFloat, with velocity: CGFloat) -> (FloatingPanelState) {
-        log.debug("targetPosition -- currentY = \(currentY), velocity = \(velocity)")
+        os_log(msg, log: devLog, type: .debug, "targetPosition -- currentY = \(currentY), velocity = \(velocity)")
 
         let sortedPositions = layoutAdapter.sortedAnchorStatesByCoordinate
 
@@ -985,7 +996,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         (fromPos, toPos) = forwardY ? (lowerPos, upperPos) : (upperPos, lowerPos)
 
         if behaviorAdapter.shouldProjectMomentum(to: toPos) == false {
-            log.debug("targetPosition -- negate projection: distance = \(distance)")
+            os_log(msg, log: devLog, type: .debug, "targetPosition -- negate projection: distance = \(distance)")
             let segment = layoutAdapter.segment(at: currentY, forward: forwardY)
             var (lowerPos, upperPos) = (segment.lower ?? sortedPositions.first!, segment.upper ?? sortedPositions.last!)
             // Equate the segment out of {top,bottom} most state to the {top,bottom} most segment
@@ -1034,10 +1045,10 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         guard let scrollView = scrollView else { return }
 
         if scrollView.isLocked {
-            log.debug("Already scroll locked.")
+            os_log(msg, log: devLog, type: .debug, "Already scroll locked.")
             return
         }
-        log.debug("lock scroll view")
+        os_log(msg, log: devLog, type: .debug, "lock scroll view")
 
         scrollIndictorVisible = scrollView.showsVerticalScrollIndicator
 
@@ -1057,7 +1068,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
     private func unlockScrollView() {
         guard let scrollView = scrollView, scrollView.isLocked else { return }
-        log.debug("unlock scroll view")
+        os_log(msg, log: devLog, type: .debug, "unlock scroll view")
 
         scrollView.bounces = scrollBounce
         scrollView.isDirectionalLockEnabled = false
@@ -1103,16 +1114,15 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         }
     }
 
-    private func allowScrollPanGesture(for scrollView: UIScrollView) -> Bool {
-        guard state == layoutAdapter.mostExpandedState else { return false }
-        var offsetY: CGFloat = 0
+    private func allowScrollPanGesture(of scrollView: UIScrollView, condition: (_ offset: CGFloat) -> Bool) -> Bool {
+        var offset: CGFloat = 0
         switch layoutAdapter.position {
         case .top, .left:
-            offsetY = value(of: scrollView.fp_contentOffsetMax - scrollView.contentOffset)
+            offset = value(of: scrollView.fp_contentOffsetMax - scrollView.contentOffset)
         case .bottom, .right:
-            offsetY = value(of: scrollView.contentOffset - contentOffsetForPinning(of: scrollView))
+            offset = value(of: scrollView.contentOffset - contentOffsetForPinning(of: scrollView))
         }
-        return offsetY <= -30.0 || offsetY > 0
+        return condition(offset)
     }
 
     // MARK: - UIPanGestureRecognizer Intermediation
@@ -1236,7 +1246,7 @@ private class NumericSpringAnimator: NSObject {
         if isRunning {
             return false
         }
-        log.debug("startAnimation --", displayLink)
+        os_log(msg, log: devLog, type: .debug, "startAnimation --", displayLink)
         isRunning = true
         displayLink.add(to: RunLoop.main, forMode: .common)
         return true
@@ -1248,7 +1258,7 @@ private class NumericSpringAnimator: NSObject {
             if locked { lock.unlock() }
         }
 
-        log.debug("stopAnimation --", displayLink)
+        os_log(msg, log: devLog, type: .debug, "stopAnimation --", displayLink)
         isRunning = false
         displayLink.invalidate()
         if withoutFinishing {

Sources/Extensions.swift

@@ -10,7 +10,7 @@ extension CGFloat {
         return (self * displayScale).rounded(.toNearestOrAwayFromZero) / displayScale
     }
     func isEqual(to: CGFloat, on displayScale: CGFloat) -> Bool {
-        return self.rounded(by: displayScale) == to.rounded(by: displayScale)
+        return rounded(by: displayScale) == to.rounded(by: displayScale)
     }
 }
 

Sources/Info.plist

@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>2.6.3</string>
+	<string>2.6.5</string>
 	<key>CFBundleVersion</key>
 	<string>$(CURRENT_PROJECT_VERSION)</string>
 </dict>

Sources/Layout.swift

@@ -1,6 +1,7 @@
 // Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
+import os.log
 
 /// An interface for generating layout information for a panel.
 @objc public protocol FloatingPanelLayout {
@@ -265,12 +266,14 @@ class LayoutAdapter {
     }
 
     var offsetFromMostExpandedAnchor: CGFloat {
+        let offset: CGFloat
         switch position {
         case .top, .left:
-            return edgePosition(surfaceView.presentationFrame) - position(for: mostExpandedState)
+            offset = edgePosition(surfaceView.presentationFrame) - position(for: mostExpandedState)
         case .bottom, .right:
-            return position(for: mostExpandedState) - edgePosition(surfaceView.presentationFrame)
+            offset = position(for: mostExpandedState) - edgePosition(surfaceView.presentationFrame)
         }
+        return offset.rounded(by: surfaceView.fp_displayScale)
     }
 
     private var hiddenAnchor: FloatingPanelLayoutAnchoring {
@@ -710,7 +713,7 @@ class LayoutAdapter {
 
     func updateInteractiveEdgeConstraint(diff: CGFloat, scrollingContent: Bool, allowsRubberBanding: (UIRectEdge) -> Bool) {
         defer {
-            log.debug("update surface location = \(surfaceLocation)")
+            os_log(msg, log: devLog, type: .debug, "update surface location = \(surfaceLocation)")
         }
 
         let minConst: CGFloat = position(for: leastCoordinateState)
@@ -750,9 +753,9 @@ class LayoutAdapter {
         defer {
             if forceLayout {
                 layoutSurfaceIfNeeded()
-                log.debug("activateLayout for \(state) -- surface.presentation = \(self.surfaceView.presentationFrame) surface.frame = \(self.surfaceView.frame)")
+                os_log(msg, log: devLog, type: .debug, "activateLayout for \(state) -- surface.presentation = \(self.surfaceView.presentationFrame) surface.frame = \(self.surfaceView.frame)")
             } else {
-                log.debug("activateLayout for \(state)")
+                os_log(msg, log: devLog, type: .debug, "activateLayout for \(state)")
             }
         }
 
@@ -787,7 +790,7 @@ class LayoutAdapter {
             if let constraints = stateConstraints[state] {
                 NSLayoutConstraint.activate(constraints)
             } else {
-                log.error("Couldn't find any constraints for \(state)")
+                os_log(msg, log: sysLog, type: .fault, "Error: can not find any constraints for \(state)")
             }
         }
     }

Sources/Logger.swift

@@ -1,100 +0,0 @@
-// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
-
-import Foundation
-import os.log
-
-// Must be a variable to use `hook` property in testing
-var log = {
-    return Logger()
-}()
-
-struct Logger {
-    private let osLog: OSLog
-    private let s = DispatchSemaphore(value: 1)
-
-    enum Level: Int, Comparable {
-        case debug = 0
-        case info = 1
-        case warning = 2
-        case error = 3
-
-        var displayName: String {
-            switch self {
-            case .debug:
-                return "Debug:"
-            case .info:
-                return "Info:"
-            case .warning:
-                return "Warning:"
-            case .error:
-                return "Error:"
-            }
-        }
-        @available(iOS 10.0, *)
-        var osLogType: OSLogType {
-            switch self {
-            case .debug: return .debug
-            case .info: return .info
-            case .warning: return .default
-            case .error: return .error
-            }
-        }
-
-        static func < (lhs: Logger.Level, rhs: Logger.Level) -> Bool {
-            return lhs.rawValue < rhs.rawValue
-        }
-    }
-
-    typealias Hook = ((String, Level) -> Void)
-    var hook: Hook?
-
-    fileprivate init() {
-        osLog = OSLog(subsystem: "com.scenee.FloatingPanel", category: "FloatingPanel")
-    }
-
-    private func log(_ level: Level, _ message: Any, _ arguments: [Any], tag: String, function: String, line: UInt) {
-        _ = s.wait(timeout: .now() + 0.033)
-        defer { s.signal() }
-
-        let extraMessage: String = arguments.map({ String(describing: $0) }).joined(separator: " ")
-        let _tag = tag.isEmpty ? "" : "\(tag):"
-        let log: String = {
-            switch level {
-            case .debug:
-                return "\(level.displayName)\(_tag) \(message) \(extraMessage) (\(function):\(line))"
-            default:
-                return "\(level.displayName)\(_tag) \(message) \(extraMessage)"
-            }
-        }()
-
-        hook?(log, level)
-
-        os_log("%{public}@", log: osLog, type: level.osLogType, log)
-    }
-
-    private func getPrettyFunction(_ function: String, _ file: String) -> String {
-        if let filename = file.split(separator: "/").last {
-            return filename + ":" + function
-        } else {
-            return file + ":" + function
-        }
-    }
-
-    func debug(_ log: Any, _ arguments: Any..., tag: String = "", function: String = #function, file: String  = #file, line: UInt = #line) {
-        #if __FP_LOG
-        self.log(.debug, log, arguments, tag: tag, function: getPrettyFunction(function, file), line: line)
-        #endif
-    }
-
-    func info(_ log: Any, _ arguments: Any..., tag: String = "",  function: String = #function, file: String  = #file, line: UInt = #line) {
-        self.log(.info, log, arguments, tag: tag, function: getPrettyFunction(function, file), line: line)
-    }
-
-    func warning(_ log: Any, _ arguments: Any..., function: String = #function, file: String  = #file, line: UInt = #line) {
-        self.log(.warning, log, arguments, tag: "", function: getPrettyFunction(function, file), line: line)
-    }
-
-    func error(_ log: Any, _ arguments: Any..., function: String = #function, file: String  = #file, line: UInt = #line) {
-        self.log(.error, log, arguments, tag: "", function: getPrettyFunction(function, file), line: line)
-    }
-}

Sources/Logging.swift

@@ -0,0 +1,17 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import os.log
+
+let msg = StaticString("%{public}@")
+let sysLog = OSLog(subsystem: Logging.subsystem, category: Logging.category)
+#if FP_LOG
+let devLog = OSLog(subsystem: Logging.subsystem, category: "\(Logging.category):dev")
+#else
+let devLog = OSLog.disabled
+#endif
+
+struct Logging {
+    static let subsystem = "com.scenee.FloatingPanel"
+    static let category = "FloatingPanel"
+    private init() {}
+}

Sources/SurfaceView.swift

@@ -1,6 +1,7 @@
 // Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
+import os.log
 
 /// An object for customizing the appearance of a surface view
 @objc(FloatingPanelSurfaceAppearance)
@@ -318,7 +319,7 @@ public class SurfaceView: UIView {
 
     public override func layoutSubviews() {
         super.layoutSubviews()
-        log.debug("surface view frame = \(frame)")
+        os_log(msg, log: devLog, type: .debug, "surface view frame = \(frame)")
 
         containerView.backgroundColor = appearance.backgroundColor
 

Tests/ControllerTests.swift

@@ -1,5 +1,6 @@
 // Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
+import OSLog
 import XCTest
 @testable import FloatingPanel
 
@@ -7,19 +8,25 @@ class ControllerTests: XCTestCase {
     override func setUp() {}
     override func tearDown() {}
 
-    func test_warningRetainCycle() {
-        let exp = expectation(description: "Warning retain cycle")
-        exp.expectedFulfillmentCount = 2 // For layout & behavior logs
-        log.hook = {(log, level) in
-            if log.contains("A memory leak will occur by a retain cycle because") {
-                XCTAssert(level == .warning)
-                exp.fulfill()
-            }
+#if swift(>=5.5)  // Avoid the 'No exact matches in call to initializer' build failure for OSLogStore when running this test case on iOS 13.7 using Xcode 12.5.1
+    func test_warningRetainCycle() throws {
+        guard #available(iOS 15.0, *) else {
+            throw XCTSkip("Unsupported iOS version: this test needs iOS 15 or later")
         }
         let myVC = MyZombieViewController(nibName: nil, bundle: nil)
         myVC.loadViewIfNeeded()
-        wait(for: [exp], timeout: 10)
+        let store = try OSLogStore(scope: .currentProcessIdentifier)
+        let found = try store
+            .getEntries(
+                at: store.position(timeIntervalSinceLatestBoot: 0),
+                matching: .init(format: "subsystem == '\(Logging.subsystem)'")
+            )
+            .contains {
+                $0.composedMessage.contains("A memory leak occurs due to a retain cycle, as")
+            }
+        XCTAssertTrue(found)
     }
+#endif
 
     func test_addPanel() {
         let rootVC = UIViewController()
@@ -34,8 +41,13 @@ class ControllerTests: XCTestCase {
         XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .tip).y)
     }
 
-    @available(iOS 12.0, *)
-    func test_updateLayout_willTransition() {
+    func test_updateLayout_willTransition() throws {
+        guard #available(iOS 12, *) else {
+            throw XCTSkip("Unsupported iOS version: this test needs iOS 12 or later")
+        }
+        if #available(iOS 17, *) {
+            throw XCTSkip("Unsupported iOS version: this test doesn't support iOS 17 or later")
+        }
         class MyDelegate: FloatingPanelControllerDelegate {
             func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
                 if newCollection.userInterfaceStyle == .dark {

Tests/CoreTests.swift

@@ -7,7 +7,7 @@ class CoreTests: XCTestCase {
     override func setUp() {}
     override func tearDown() {}
 
-    func test_scrolllock() {
+    func test_scrollLock() {
         let fpc = FloatingPanelController()
 
         let contentVC1 = UITableViewController(nibName: nil, bundle: nil)