在正弦波路径上动画UIView

Question

如何让UIView沿着正弦波路径移动？理想情况下，我可以在UIView关闭屏幕并释放它时停止动画。我发现UIView-> animateWithDuration一次只能在一个属性上进行动画制作，但这似乎是两个独有的事情同时发生的：它正在向右移动，并向上/向下移动。

Answer 1

你可以用简单的CAKeyframeAnimation来做到这一点。

override func viewDidLoad() { 
    super.viewDidLoad() 

    let myView = UIView(frame: CGRect(x: 10, y: 100, width: 50, height: 50)) 
    myView.backgroundColor = UIColor.cyan 
    view.addSubview(myView) 

    let animation = CAKeyframeAnimation() 
    animation.keyPath = "position" 
    animation.duration = 60 // 60 seconds 
    animation.isAdditive = true // Make the animation position values that we later generate relative values. 

    // From x = 0 to x = 299, generate the y values using sine. 
    animation.values = (0..<300).map({ (x: Int) -> NSValue in 
     let xPos = CGFloat(x) 
     let yPos = sin(xPos) 

     let point = CGPoint(x: xPos, y: yPos * 10) // The 10 is to give it some amplitude. 
     return NSValue(cgPoint: point) 
    }) 
    myView.layer.add(animation, forKey: "basic") 
}