ios - 使用按钮停止动画方 block

Question

我试图用一个按钮停止在 View 中动画的正方形(循环上下)并读取位置(x，y)这是运动的代码

override func viewDidLoad() {
    super.viewDidLoad()

    while buttonPress == false {
    movement()
    }
}

func movement() {
    coloredSquare.backgroundColor = UIColor.blueColor()
    coloredSquare.frame = CGRect(x:0, y:500, width:50, height:50)
    self.view.addSubview(coloredSquare)
    movementDown()
}

func movementDown() {
    // lets set the duration to 1.0 seconds
    // and in the animations block change the background color
    // to red and the x-position  of the frame
    UIView.animateWithDuration(1.0, animations: {
        self.coloredSquare.backgroundColor = UIColor.blueColor()
        self.coloredSquare.frame = CGRect(x: 0, y: 500, width: 50, height: 50)
        }, completion: { animationFinished in
            self.movementUp()
    })
}

func movementUp() {
    UIView.animateWithDuration(1.0, animations: {
        self.coloredSquare.backgroundColor = UIColor.redColor()
        self.coloredSquare.frame = CGRect(x: 0, y: 0, width: 50, height: 50)
        }, completion: { animationFinished in
            self.movementDown()
    })
}

如果我尝试使用 WHILE 执行方法直到条件为假，Xcode 构建但模拟器在启动屏幕停止，如果我取消 while 条件，动画工作但没有阻止它......谁能帮我？谢谢

Answer 1

首先，摆脱 while 循环。在动画的完成 block 中，首先检查动画是否已完成，然后再调用另一个动画——如果取消动画，则不会为真，因此动画将停止。在您的按钮方法中，您需要访问 coloredSquare 的表示层以获取其当前位置，并取消所有动画以使动画立即停止。

class ViewController: UIViewController {

var coloredSquare: UIView = UIView()

override func viewDidLoad() {
    super.viewDidLoad()
    [self .movement()];
}


func movement() {

    coloredSquare.backgroundColor = UIColor.blueColor()

    coloredSquare.frame = CGRect(x:0, y:500, width:50, height:50)

    self.view.addSubview(coloredSquare)

    movementDown()
}

func movementDown() {

    UIView.animateWithDuration(3.0, animations: {
        self.coloredSquare.backgroundColor = UIColor.blueColor()
        self.coloredSquare.frame = CGRect(x: 0, y: 500, width: 50, height: 50)
        }, completion: { animationFinished in
            if animationFinished {
                self.movementUp()
            }
    })
}

func movementUp() {
    UIView.animateWithDuration(3.0, animations: {
        self.coloredSquare.backgroundColor = UIColor.redColor()
        self.coloredSquare.frame = CGRect(x: 0, y: 0, width: 50, height: 50)
        }, completion: { animationFinished in
            if animationFinished {
                self.movementDown()
            }
    })
}



@IBAction func stopBlock(sender: AnyObject) {
    var layer = coloredSquare.layer.presentationLayer() as CALayer
    var frame = layer.frame
    println(frame)
    coloredSquare.layer.removeAllAnimations()
    coloredSquare.frame = frame // You need this to keep the block where it was when you cancelled the animation, otherwise it will jump to the position defined by the end of the current animation
}