Update library

README.md

@@ -1,3 +1,8 @@
 # QQPercentDrivenInteractiveTransition
 
-A description of this package.
+`QQPercentDrivenInteractiveTransition` is a drop-in replacement for `UIPercentDrivenInteractiveTransition` for use in custom container view controllers.
+
+Why do you need it? Because Apples own `UIPercentDrivenInteractiveTransition` calls undocumented methods on your custom `UIViewControllerContextTransitioning` objects.
+
+Note that this class can be used with UIKits standard container view controllers such as `UINavigationController`, `UITabBarController` and also for presenting modal view controllers.
+

Sources/QQPercentDrivenInteractiveTransition/QQPercentDrivenInteractiveTransition.swift

@@ -1,3 +1,135 @@
-struct QQPercentDrivenInteractiveTransition {
-    var text = "Hello, World!"
+//
+//  QQPercentDrivenInteractiveTransition.swift
+//  QoQa
+//
+//  Created by Alexandre on 23.09.20.
+//  Copyright © 2020 QoQa Services SA. All rights reserved.
+//
+
+import UIKit
+
+open class QQPercentDrivenInteractiveTransition: NSObject {
+
+    // MARK: - Init
+    public required init(animator: UIViewControllerAnimatedTransitioning) {
+        self.animator = animator
+    }
+
+    // MARK: - Setters and getters
+    public let animator: UIViewControllerAnimatedTransitioning
+    public var completionSpeed: CGFloat = 1.0
+    public var duration: TimeInterval {
+        return self.animator.transitionDuration(using: self.transitionContext)
+    }
+    public fileprivate(set) var percentComplete: CGFloat = 0.0
+
+    // MARK: - Private Helpers
+    fileprivate weak var transitionContext: UIViewControllerContextTransitioning?
+
+    fileprivate var animationDisplayLink: CADisplayLink? = nil {
+        willSet {
+            guard self.animationDisplayLink != newValue else {
+                return
+            }
+
+            self.animationDisplayLink?.invalidate()
+        }
+    }
+
+    // MARK: - Finalization
+    deinit {
+        self.animationDisplayLink = nil
+    }
+}
+
+// MARK: - Managing the Interactive Transition
+extension QQPercentDrivenInteractiveTransition: UIViewControllerInteractiveTransitioning {
+
+    public func startInteractiveTransition(_ transitionContext: UIViewControllerContextTransitioning) {
+
+        guard self.transitionContext == nil else {
+            return
+        }
+
+        self.transitionContext = transitionContext
+
+        self.transitionContainerLayer?.speed = 0.0
+
+        self.animator.animateTransition(using: transitionContext)
+    }
+
+    open func update(_ percentComplete: CGFloat) {
+
+        self.percentComplete = min(1.0, max(0.0, percentComplete))
+
+        self.transitionContainerLayer?.timeOffset = TimeInterval(self.percentComplete) * self.duration
+
+        self.transitionContext?.updateInteractiveTransition(self.percentComplete)
+    }
+
+    open func cancel() {
+        self.transitionContext?.cancelInteractiveTransition()
+        self.completeTransition()
+    }
+
+    open func finish() {
+        self.transitionContext?.finishInteractiveTransition()
+        self.completeTransition()
+    }
+}
+
+// MARK: - Managing Animator Progressive Transition
+extension QQPercentDrivenInteractiveTransition {
+
+    fileprivate var transitionContainerLayer: CALayer? {
+        return self.transitionContext?.containerView.layer
+    }
+
+    fileprivate func completeTransition() {
+
+        guard self.animationDisplayLink == nil else {
+            return
+        }
+
+        self.animationDisplayLink = CADisplayLink(target: self, selector: #selector(completeTransitionUpdate))
+        self.animationDisplayLink?.add(to: .main, forMode: .common)
+    }
+
+    @objc fileprivate func completeTransitionUpdate(sender: CADisplayLink) {
+
+        guard let transitionContext = self.transitionContext, let layer = self.transitionContainerLayer else {
+            return
+        }
+
+        var deltaTimeOffset = sender.duration * TimeInterval(self.completionSpeed)
+        deltaTimeOffset *= transitionContext.transitionWasCancelled ? -1.0 : 1.0
+        let timeOffset = layer.timeOffset + deltaTimeOffset
+
+        if timeOffset < 0.0 || timeOffset > self.duration {
+            self.completeTransitionDidFinish()
+        } else {
+            layer.timeOffset = timeOffset
+        }
+    }
+
+    private func completeTransitionDidFinish() {
+
+        self.animationDisplayLink = nil
+
+        guard let transitionContext = self.transitionContext, let layer = self.transitionContainerLayer else {
+            return
+        }
+
+        layer.speed = 1.0
+
+        if !transitionContext.transitionWasCancelled {
+            let pausedTime = layer.timeOffset
+            layer.timeOffset = 0.0
+            layer.beginTime = 0.0  // Need to reset to zero to avoid flickering
+            let timeSincePause = layer.convertTime(CACurrentMediaTime(), from: nil) - pausedTime
+            layer.beginTime = timeSincePause
+        }
+
+        self.transitionContext = nil
+    }
 }

Tests/QQPercentDrivenInteractiveTransitionTests/QQPercentDrivenInteractiveTransitionTests.swift

@@ -2,14 +2,23 @@ import XCTest
 @testable import QQPercentDrivenInteractiveTransition
 
 final class QQPercentDrivenInteractiveTransitionTests: XCTestCase {
-    func testExample() {
-        // This is an example of a functional test case.
-        // Use XCTAssert and related functions to verify your tests produce the correct
-        // results.
-        XCTAssertEqual(QQPercentDrivenInteractiveTransition().text, "Hello, World!")
+
+    func testInstantiation() {
+        class CustomAnimator: NSObject, UIViewControllerAnimatedTransitioning {
+
+            func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
+                return 0.18
+            }
+
+            func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {}
+        }
+        let transition = QQPercentDrivenInteractiveTransition(animator: CustomAnimator())
+
+        XCTAssertEqual(transition.duration, 0.18)
+        XCTAssertEqual(transition.percentComplete, 0)
     }
 
     static var allTests = [
-        ("testExample", testExample),
+        ("testInstantiation", testInstantiation),
     ]
 }