如何在 CADisplayLink 中设置延迟

Question

我正在使用CADisplayLink 为 10 个不同的按钮设置动画，但这些按钮都聚集在一起。所以我的问题是如何实现延迟以使每个按钮在不同的时间进行动画处理，这样它们就不会全部聚集在一起。

var buttons:[UIButton] = Array()

override func viewDidLoad() {
    super.viewDidLoad()

    var displayLink = CADisplayLink(target: self, selector: "handleDisplayLink:")
    displayLink.addToRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)

    for index in 0...10 - 1{

        buttons.append(UIButton.buttonWithType(.System) as UIButton)

        var xLocation:CGFloat = CGFloat(arc4random_uniform(300) + 30)

        buttons[index].frame = CGRectMake(xLocation, 10, 100, 100)
        buttons[index].setTitle("Test Button \(index)", forState: UIControlState.Normal)
        buttons[index].addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)

        self.view.addSubview(buttons[index])

    }



}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()

}

func handleDisplayLink(displayLink: CADisplayLink) {

    for index in 0...10 - 1{

        var buttonFrame = buttons[index].frame
        buttonFrame.origin.y += 1
        buttons[index].frame = buttonFrame
        if buttons[index].frame.origin.y >= 500 {
            displayLink.invalidate()
        }
    }
}


func buttonAction(sender: UIButton) {
    sender.alpha = 0
}

Answer 1

要制作延迟动画，您可以只使用UIView.animateWithDuration 函数而不是CADisplayLink。例如

override func viewDidLoad() {
    for index in 0...10 - 1{

        buttons.append(UIButton.buttonWithType(.System) as UIButton)

        var xLocation:CGFloat = CGFloat(arc4random_uniform(300) + 30)

        buttons[index].frame = CGRectMake(xLocation, 10, 100, 100)
        buttons[index].setTitle("Test Button \(index)", forState: UIControlState.Normal)
        buttons[index].addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)

        self.view.addSubview(buttons[index])

        // Change this line to change the delay between the button animations.
        let delay : NSTimeInterval = 1.0 * NSTimeInterval(index) 

        UIView.animateWithDuration(2.0, delay: delay, options: UIViewAnimationOptions.CurveLinear, animations: { () -> Void in

            var buttonFrame = self.buttons[index].frame
            buttonFrame.origin.y = 500
            self.buttons[index].frame = buttonFrame


        }, completion: { (finished) -> Void in

        })

    }
}