停止无限旋转图像的正确方法?如何实现removeAllAnimations?

有几种方法可以满足您的要求:

1. UIViewPropertyAnimator

    private var animator: UIViewPropertyAnimator?
   
    deinit {
        animator?.stopAnimation(true)
    }
   
    @IBAction func didTapButton(_ sender: Any) {
        guard let animator = animator else {
            createAnimation()
            return
        }
   
        if animator.isRunning {
            animator.pauseAnimation()
        } else {
            animator.startAnimation()
        }
    }
   
    /// Create and start 360 degree animation
    ///
    /// This will fire off another animation when one 360° rotation finishes.
   
    private func createAnimation() {
        animator = UIViewPropertyAnimator.runningPropertyAnimator(withDuration: 4, delay: 0, options: .curveLinear) { [self] in
            UIView.animateKeyframes(withDuration: 4, delay: 0) {
                UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 1.0 / 3.0) {
                    animatedView.transform = .init(rotationAngle: .pi * 2 * 1 / 3)
                }
                UIView.addKeyframe(withRelativeStartTime: 1.0 / 3.0, relativeDuration: 1.0 / 3.0) {
                    animatedView.transform = .init(rotationAngle: .pi * 2 * 2 / 3)
                }
                UIView.addKeyframe(withRelativeStartTime: 2.0 / 3.0, relativeDuration: 1.0 / 3.0) {
                    animatedView.transform = .identity
                }
            }
        } completion: { [weak self] _ in
            self?.createAnimation()
        }
    }
   

2. 也可以使用UIKit Dynamics旋转项目。然后可以删除 UIDynamicItemBehavior 这是执行旋转,它只是停在原地。它会自动离开视图 transform UIDynamicItemHavior

    private lazy var animator = UIDynamicAnimator(referenceView: view)
    private var rotate: UIDynamicItemBehavior!
   
    @IBAction func didTapButton(_ sender: Any) {
        if let rotate = rotate {
            animator.removeBehavior(rotate)
            self.rotate = nil
        } else {
            rotate = UIDynamicItemBehavior(items: [animatedView])
            rotate.allowsRotation = true
            rotate.angularResistance = 0
            rotate.addAngularVelocity(1, for: animatedView)
            animator.addBehavior(rotate)
        }
    }
   

   这不允许您轻松控制旋转速度的时间,而是由 angularVelocity ,但这是一种非常简单的方法(支持iOS 7.0及更高版本)。

3. 停止动画并将其保留在停止位置的老派方法是捕捉 presentationLayer

    private var isAnimating = false
   
    @IBAction func didTapButton(_ sender: Any) {
        if isAnimating {
            let transform = animatedView.layer.presentation()!.transform
            animatedView.layer.removeAllAnimations()
            animatedView.layer.transform = transform
        } else {
            let rotate = CABasicAnimation(keyPath: "transform.rotation")
            rotate.byValue = 2 * CGFloat.pi
            rotate.duration = 4
            rotate.repeatCount = .greatestFiniteMagnitude
            animatedView.layer.add(rotate, forKey: nil)
        }
   
        isAnimating = !isAnimating
    }
   

4. 如果你想使用 UIView 基于块的动画,必须捕捉停止动画的角度,以便知道从何处重新启动动画。诀窍是抓住 m12 和 m11 的 CATransform3D :

    angle = atan2(transform.m12, transform.m11)
   

    private var angle: CGFloat = 0
    private var isAnimating = false
   
    @IBAction func didTapButton(_ sender: Any) {
        if isAnimating {
            let transform = animatedView.layer.presentation()!.transform
            angle = atan2(transform.m12, transform.m11)
            animatedView.layer.removeAllAnimations()
            animatedView.layer.transform = transform
        } else {
            UIView.animate(withDuration: 4, delay: 0, options: .curveLinear) { [self] in
                UIView.animateKeyframes(withDuration: 4, delay: 0, options: .repeat) {
                    UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 1.0 / 3.0) {
                        animatedView.transform = .init(rotationAngle: self.angle + .pi * 2 * 1 / 3)
                    }
                    UIView.addKeyframe(withRelativeStartTime: 1.0 / 3.0, relativeDuration: 1.0 / 3.0) {
                        animatedView.transform = .init(rotationAngle: self.angle + .pi * 2 * 2 / 3)
                    }
                    UIView.addKeyframe(withRelativeStartTime: 2.0 / 3.0, relativeDuration: 1.0 / 3.0) {
                        animatedView.transform = .init(rotationAngle: self.angle)
                    }
                }
            }
        }
   
        isAnimating = !isAnimating
    }
   

5. 您可以使用旋转对象 CADisplayLink 将角度更新为某个计算值。然后停止旋转就像使显示链接无效一样简单,从而使其保持停止时的状态。然后,只需将显示链接添加回runloop,即可恢复动画。

   这种技术提供了大量的控制,但却是最不优雅的方法。

let animationFrequency = 30.0
 func rotateView(targetView: UIView, duration: Double = 1.0 / animationFrequency) {
        UIView.animate(withDuration: duration, delay: 0.0, options: .curveLinear, animations: {
            targetView.transform = targetView.transform.rotated(by: CGFloat(Double.pi / animationFrequency))
        }) { finished in
            self.rotateView(targetView: targetView, duration: duration)
        }
    }

我有一个无限的“翻转”到标签(这是一个水印),我需要“关闭”到一个特定的标签(或水印)时,股票期权正在显示。所有这些都是通过计时器实现的——在翻页之前,将特定标签查看几秒钟。当你这样做时,只需关闭计时器。

public class FlipView:UIView {

    private var labelWatermark:FlipLabel!
    private var labelTap:FlipLabel!

    let transitionOptions: UIViewAnimationOptions = [.transitionFlipFromRight, .showHideTransitionViews]
    var isLabel1 = true
    var timer:Timer!

    convenience public init(appName:String) {

        self.init(frame: CGRect.zero)

        labelTap = FlipLabel("Tap to remove", "Watermark")
        self.addSubview(labelTap)

        labelWatermark = FlipLabel("created with", appName)
        self.addSubview(labelWatermark)

        timer = Timer.scheduledTimer(
            timeInterval: 3.0, target: self, selector: #selector(flipViews),
            userInfo: nil, repeats: true)
        timer.fire()

    }

    internal func startFlip() {
        timer = Timer.scheduledTimer(
            timeInterval: 3.0, target: self, selector: #selector(flipViews),
            userInfo: nil, repeats: true)
        timer.fire()
    }

    internal func stopFlip() {
        timer.invalidate()
        UIView.transition(from: labelTap, to: labelWatermark, duration: 1, options: transitionOptions, completion: nil)
        isLabel1 = true
    }

    @objc func flipViews() {
        if (isLabel1) {
            UIView.transition(from: labelWatermark, to: labelTap, duration: 1, options: transitionOptions, completion: nil)
            isLabel1 = false
        } else {
            UIView.transition(from: labelTap, to: labelWatermark, duration: 1, options: transitionOptions, completion: nil)
            isLabel1 = true
        }
    }
}