如何在Swift中下一个动画开始之前等待一个动画完成？

Question

如何在Swift中下一个动画开始之前等待一个动画完成？ 我一直在搞乱if animation.animationDidStop... {} ，但它不会起作用。

这是我目前的一些代码：

class ViewController: UIViewController {
@IBOutlet weak var purpleRing: UIImageView!
@IBOutlet weak var beforeCountdownAnimation: UIImageView!

var imageArray = [UIImage]()
var imageArray2 = [UIImage]()

override func viewDidLoad() {
    super.viewDidLoad()

    for e in -17...0 {
    let imageName2 = "\(e)"
        imageArray2.append(UIImage(named: imageName2)!)
    }

    for t in 1...97 {
        let imageName = "\(t)"
        imageArray.append(UIImage(named: imageName)!)
    }
}

func startAnimation() -> Void {
    purpleRing.animationImages = imageArray
    purpleRing.animationDuration = 5.0
    purpleRing.startAnimating()
}

func startAnimation2() -> Void {
    beforeCountdownAnimation.animationImages = imageArray2
    beforeCountdownAnimation.animationDuration = 1.0
    beforeCountdownAnimation.startAnimating()
}

@IBAction func startAnimations(sender: AnyObject) {
    startAnimation()
    startAnimation2()
}

Answer 1

嗯，可能之前回答过，但你可以使用Grand Central Dispatch dispatc_aysnc。

我们的想法是，您知道动画持续时间，因此您可以使用它来告诉GDC何时执行下一个代码。 所以类似于：

// call animation 1, which you specified to have 5 second duration
CGFloat animation1Duration = 5.0;
CGFloat animation2Duration = 7.0;

playAnimation1WithDuration(animation1Duration);

// calling second animation block of code after 5.0 using GDC
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(animation1Duration * Double(NSEC_PER_SEC))), dispatch_get_main_queue(), { () -> Void in

    print("5.0 has passed");

    // call second animation block here
    playAnimation2WithDuration(animation2Duration);

});

Answer 2

对于一个又一个动画，您也可以使用NSTimer ......

看到我的代码，它可能会有所帮助......

class ViewController: UIViewController {

@IBOutlet weak var IBimg1: UIImageView!
@IBOutlet weak var IBimg2: UIImageView!
@IBOutlet weak var IBimg3: UIImageView!

override func viewDidLoad() {
    super.viewDidLoad()

    startAnimation1()

}

func startAnimation1(){

NSTimer.scheduledTimerWithTimeInterval(2.0, target: self, selector: Selector("startAnimation2"), userInfo: self, repeats: false)

UIView.animateWithDuration(2.0, animations: {

        self.IBimg1.alpha = 0

    })

}

func startAnimation2(){

NSTimer.scheduledTimerWithTimeInterval(2.0, target: self, selector: Selector("startAnimation3"), userInfo: self, repeats: false)

    UIView.animateWithDuration(2.0, animations: {

        self.IBimg2.alpha = 0

    })

}

func startAnimation3(){

    UIView.animateWithDuration(2.0, animations: {

        self.IBimg3.alpha = 0

    })

}


override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

说明...

• 这里startAnimation1（）方法在viewDidLoad（）中调用
• 然后我打电话的NSTimer对startAnimation2（）方法，在这里指出，startAnimation2（）方法被调用...，即在首先结束的动画2秒后...

谢谢