如何在两个动画之间设置延迟序列

Question

我有一个UIImageView我想旋转180度，占用1秒，然后我想在此位置等待1秒，然后将180度旋转回到原始位置，占用1秒。

我该如何完成？我尝试了100种方法，但它会不断回弹而不是回滚

编辑：我忘了补充，我需要这个无限期地重复

Answer 1

您可以在UIView.animate上显示的完成处理程序中执行第二个动画

let duration = self.transitionDuration(using: transitionContext)

let firstAnimDuration = 0.5
UIView.animate(withDuration: firstAnimDuration, animations: {
    /* Do here the first animation */
}) { (completed) in

   let secondAnimDuration = 0.5
   UIView.animate(withDuration: secondAnimDuration, animations: { 
       /* Do here the second animation */
   })
}

现在您可能会遇到另一个问题。

如果使用CGAffineTransform旋转视图，并且为每个动画将一个这种类型的新对象分配给view.transform，则将丢失先前的变换操作

因此，根据这篇文章：如何在Swift中应用多个转换，您需要进行转换操作

带有2个动画块的示例

这是旋转180度并在1秒后返回原点的示例：

let view = UIView.init(frame: CGRect.init(origin: self.view.center, size: CGSize.init(width: 100, height: 100)))
view.backgroundColor = UIColor.red
self.view.addSubview(view)

var transform = view.transform
transform = transform.rotated(by: 180)

UIView.animate(withDuration: 2, animations: {
    view.transform = transform
}) { (completed) in

    transform = CGAffineTransform.identity
    UIView.animate(withDuration: 2, delay: 1, options: [], animations: { 
        view.transform = transform
    }, completion: nil)
}

.repeat动画和.autoreverse的示例

.animate方法使您能够设置一些动画选项。特别是结构UIViewAnimationOptions包含：

1. .repeat，无限期重复您的动画块
2. .autoreverse，将您的视图恢复为原始状态

考虑到这一点，您可以执行以下操作：

var transform = view.transform.rotated(by: 180)
UIView.animate(withDuration: 2, delay: 0, options: [.repeat, .autoreverse], animations: {
     self.myView.transform = transform
})

但是您需要在两个动画之间进行延迟，因此您需要执行以下操作：

递归动画示例和延迟1秒

只需在ViewController中创建一个动画视图的方法即可。在最后一个完成处理程序中，只需调用该方法即可创建无限循环。

最后，您需要在viewDidAppear上调用方法以启动动画。

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    self.animation()
}


func animation() {
    var transform = view.transform
    transform = transform.rotated(by: 180)

    UIView.animate(withDuration: 2, delay: 0, options: [], animations: {

        self.myView.transform = transform

    }) { bool in
        transform = CGAffineTransform.identity

        UIView.animate(withDuration: 2, delay: 1, options: [], animations: {

            self.myView.transform = transform

        }, completion: { bool in
            self.animation()
        })
    }
}

Answer 2

您需要做的就是创建一个keyFrame动画。它旨在将多个动画链接在一起，并在第一个关键帧中旋转UIImageView子类PI，然后在第二个关键帧中将其转换回identity。

        let rotateForwardAnimationDuration: TimeInterval = 1
        let rotateBackAnimationDuration: TimeInterval = 1
        let animationDuration: TimeInterval = rotateForwardAnimationDuration + rotateBackAnimationDuration

        UIView.animateKeyframes(withDuration: animationDuration, delay: 0, options: [], animations: { 
            UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: rotateForwardAnimationDuration) {
                self.imageView.transform = CGAffineTransform(rotationAngle: .pi)
            }

            UIView.addKeyframe(withRelativeStartTime: 0.5, relativeDuration: rotateBackAnimationDuration) { 
                self.imageView.transform = .identity 
            }
        })

结果：

编辑： 这是一个示例，如何使其无限期运行。我想您的图像在viewController中，并且您拥有对imageView的一些引用。

因此，例如，在上viewDidAppear，调用触发动画的函数，然后在动画的完成块中再次调用同一函数。

class ViewController: UIViewController {

    @IBOutlet weak var imageView: UIImageView!

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        self.runRotateAnimation()
    }

    func runRotateAnimation() {
        let rotateForwardAnimationDuration: TimeInterval = 1
        let rotateBackAnimationDuration: TimeInterval = 1
        let animationDuration: TimeInterval = rotateForwardAnimationDuration + rotateBackAnimationDuration

        UIView.animateKeyframes(withDuration: animationDuration, delay: 0, options: [], animations: { 
            UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: rotateForwardAnimationDuration) {
                self.imageView.transform = CGAffineTransform(rotationAngle: .pi)
            }

            UIView.addKeyframe(withRelativeStartTime: 0.5, relativeDuration: rotateBackAnimationDuration) { 
                self.imageView.transform = .identity 
            }
        }) { (isFinished) in
            // To loop it continuosly, just call the same function from the completion block of the keyframe animation
            self.runRotateAnimation()
        }
    }
}