如何添加屏幕边缘平移手势识别器来处理此流行动画？

Question

我分类为UINavigationController，并创建了一个处理推送和弹出转换的非交互式动画对象。要完成此操作，我如何添加​​来处理下面的自定义流行动画？我有点困惑从哪里去，所以任何帮助将是伟大的，谢谢！

class CustomNavigationController: UINavigationController { 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     delegate = self 
     isNavigationBarHidden = true 

    } 

} 

extension CustomNavigationController: UINavigationControllerDelegate { 

    // noninteractive animator objects 
    func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationControllerOperation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? { 

     switch operation { 

     case .push: 
      return CustomPushAnimator() 

     case .pop: 
      return CustomPopAnimator() 

     default: 
      return nil 

     } 

    } 

    // the interactive animator controller 
    func navigationController(_ navigationController: UINavigationController, interactionControllerFor animationController: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? { 

     switch animationController { 

     case is CustomPopAnimator: 
      return CustomInteractiveController() 

     default: 
      return nil 

    } 

} 

// the noninteractive push animator 
class CustomPushAnimator: NSObject, UIViewControllerAnimatedTransitioning { 

    // push transition duration 
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval { 

     return 0.2 

    } 

    // push transition animation 
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) { 

     let viewWidth = UIScreen.main.bounds.width 
     let viewHeight = UIScreen.main.bounds.height 
     let containerView = transitionContext.containerView 
     let toViewController = transitionContext.viewController(forKey: .to) 

     containerView.addSubview((toViewController?.view)!) 
     toViewController?.view.frame = CGRect(x: viewWidth, y: 0, width: viewWidth, height: viewHeight) 

     UIView.animate(withDuration: transitionDuration(using: transitionContext), delay: 0, options: UIViewAnimationOptions.curveEaseInOut, animations: { 
      toViewController?.view.frame = CGRect(x: 0, y: 0, width: viewWidth, height: viewHeight) 
     }, completion: { finished in 
      transitionContext.completeTransition(!transitionContext.transitionWasCancelled) 
     }) 

    } 

} 

// the noninteractive pop animator 
class CustomPopAnimator: NSObject, UIViewControllerAnimatedTransitioning { 

    // pop transition duration 
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval { 

     return 0.2 

    } 

    // pop transition animation 
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) { 

     let viewWidth = UIScreen.main.bounds.width 
     let viewHeight = UIScreen.main.bounds.height 
     let containerView = transitionContext.containerView 
     let fromViewController = transitionContext.viewController(forKey: .from) 
     let toViewController = transitionContext.viewController(forKey: .to) 

     containerView.insertSubview((toViewController?.view)!, belowSubview: (fromViewController?.view)!) 

     UIView.animate(withDuration: transitionDuration(using: transitionContext), delay: 0, options: UIViewAnimationOptions.curveEaseInOut, animations: { 
      fromViewController?.view.frame = CGRect(x: viewWidth, y: 0, width: viewWidth, height: viewHeight) 
     }, completion: { finished in 
      fromViewController?.view.removeFromSuperview() 
      transitionContext.completeTransition(!transitionContext.transitionWasCancelled) 
     }) 

    } 

} 

class CustomInteractiveController: NSObject, UIViewControllerInteractiveTransitioning { 

    func startInteractiveTransition(_ transitionContext: UIViewControllerContextTransitioning) { 

     // I think the edge screen pan gesture goes here? Again, any advice is greatly appreciated! 

    } 

} 

Answer 1

一般情况下，写一个互动的自定义过渡动画的程序是：转变开始

1. 之前，必须给予负责的过渡委托的视图控制器。

2. 您将拥有一个跟踪交互式手势的手势识别器。当手势识别器识别时，它触发到新视图控制器的转换。

3. 随着转换开始，代表将被要求提供动画控制器。您将返回一个UIViewControllerAnimatedTransitioning对象。

4. 该代表还将被要求提供交互控制器。您将返回一个UIViewControllerInteractiveTransitioning对象（或nil以防止转换为交互式）。该对象实现了startInteractiveTransition(_:)。

5. 手势识别器继续在转换上下文中不断调用updateInteractiveTransition(_:)，并管理动画帧。

6. 手势迟早会结束。此时，我们必须决定是否宣布过渡完成或取消。一种典型的方法是说，如果用户执行了超过一半的完整手势，则构成完成;否则，它构成取消。我们相应地完成动画。

7. 动画现在已完成，其完成功能被调用。我们必须调用转换上下文的finishInteractiveTransition或cancelInteractiveTransition，然后用一个参数来调用其completeTransition(_:)，该参数指出转换是完成还是取消。

8. 我们的animationEnded被调用，我们清理。

在过去，你可以使用一个UIPercentDrivenInteractiveTransition对象来帮助你，但我总是用我的自定义过渡动画时下UIViewPropertyAnimator（iOS版10及更高版本）;你将不得不开始重写你的整个代码来做到这一点。我通常保留三个实例属性：UIViewPropertyAnimator，转换上下文（因为手势识别器需要引用）以及一个Bool标志，表明这是否是交互式动画（因为相同的代码可以重复用于交互式和非交互式版本动画）。