使用animateKeyframesWithDuration在屏幕上创建一个连续旋转的方块

Question

我尝试使用下面的代码在屏幕上创建一个连续旋转的方块.但我不知道为什么转速在变化.如何更改代码以使旋转速度不变？我尝试了不同UIViewKeyframeAnimationOptions,但似乎没有一个工作.

override func viewDidLoad() {
    super.viewDidLoad()

    let square = UIView()
    square.frame = CGRect(x: 55, y: 300, width: 40, height: 40)
    square.backgroundColor = UIColor.redColor()
    self.view.addSubview(square)

    let duration = 1.0
    let delay = 0.0
    let options = UIViewKeyframeAnimationOptions.Repeat
        UIView.animateKeyframesWithDuration(duration, delay: delay, options: options, animations: {
        let fullRotation = CGFloat(M_PI * 2)

        UIView.addKeyframeWithRelativeStartTime(0, relativeDuration: 1/3, animations: {
            square.transform = CGAffineTransformMakeRotation(1/3 * fullRotation)
        })                        
        UIView.addKeyframeWithRelativeStartTime(1/3, relativeDuration: 1/3, animations: {
            square.transform = CGAffineTransformMakeRotation(2/3 * fullRotation)
        })                        
        UIView.addKeyframeWithRelativeStartTime(2/3, relativeDuration: 1/3, animations: {
            square.transform = CGAffineTransformMakeRotation(3/3 * fullRotation)
        })
        }, completion: {finished in
        })
    }         

Answer 1

我之前遇到过同样的问题,这就是我的工作方式:

let raw = UIViewKeyframeAnimationOptions.Repeat.rawValue | UIViewAnimationOptions.CurveLinear.rawValue
let options = UIViewKeyframeAnimationOptions(rawValue: raw)

在放弃之前,我想出了这个问题.我不认为有关于它的文档,但它只是工作.

Answer 2

这真的很奇怪......UIView.animateKeyframesWithDuration并没有像我期望的那样工作，并UIViewKeyframeAnimationOptions.CalculationModeLinear|UIViewKeyframeAnimationOpti\xe2\x80\x8c\xe2\x80\x8bons.Repeat通过选项传递。

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如果您使用非块方法创建关键帧动画（见下文），旋转将按预期重复。

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如果我发现为什么基于块的选项不起作用，我会尝试并记住在这里更新答案！

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override func viewDidLoad() {\n    super.viewDidLoad()\n\n\n    let square = UIView()\n    square.frame = CGRect(x: 55, y: 300, width: 40, height: 40)\n    square.backgroundColor = UIColor.redColor()\n    self.view.addSubview(square)\n\n    let fullRotation = CGFloat(M_PI * 2)\n\n    let animation = CAKeyframeAnimation()\n    animation.keyPath = "transform.rotation.z"\n    animation.duration = 2\n    animation.removedOnCompletion = false\n    animation.fillMode = kCAFillModeForwards\n    animation.repeatCount = Float.infinity\n    animation.values = [fullRotation/4, fullRotation/2, fullRotation*3/4, fullRotation]\n\n    square.layer.addAnimation(animation, forKey: "rotate")\n\n}\n

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