在presentViewController之后，CAKeyFrameAnimation无法正常工作

Question

我的代码工作正常，并在根视图控制器中正确设置动画。 但当我将它移动到另一个VC并使用presentViewController在那里导航时，图像静态显示并且没有动画。

Root View Controller

       @IBAction func glassFillingButtonClicked(sender: UIButton) {
    let storyBoard = UIStoryboard(name: "Main", bundle:nil)

    let nextViewController = storyBoard.instantiateViewControllerWithIdentifier("waterFilling") as! GlassFillingViewController
    self.presentViewController(nextViewController, animated:true, completion:nil)

waterFillingVC

    class GlassFillingViewController: UIViewController {
@IBOutlet weak var dropView: UIView!
@IBOutlet weak var dropImage: UIImageView!
@IBOutlet weak var dropImage2: UIImageView!
@IBOutlet weak var dropImage3: UIImageView!
@IBOutlet weak var dropImage4: UIImageView!
@IBOutlet weak var dropImage5: UIImageView!
@IBOutlet weak var dropImage6: UIImageView!

override func viewDidLoad() {
    super.viewDidLoad()
    dropAnimation()
    // Do any additional setup after loading the view, typically from a nib.
}

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

func addWaterDroppingAnimation(beginTime: CFTimeInterval) -> CAKeyframeAnimation {
    let waterDroppingAnimation = CAKeyframeAnimation.init(keyPath: "opacity")
    waterDroppingAnimation.beginTime = beginTime
    waterDroppingAnimation.duration = 1.0
    waterDroppingAnimation.values = [0.2,1,0.2]
    waterDroppingAnimation.repeatCount = HUGE
    return waterDroppingAnimation
}

func dropAnimation() {
    dropImage.layer.addAnimation(addWaterDroppingAnimation(0.0), forKey: "basic")
    dropImage2.layer.addAnimation(addWaterDroppingAnimation(0.2), forKey: "basic")
    dropImage3.layer.addAnimation(addWaterDroppingAnimation(0.4), forKey: "basic")
    dropImage4.layer.addAnimation(addWaterDroppingAnimation(0.6), forKey: "basic")
    dropImage5.layer.addAnimation(addWaterDroppingAnimation(0.8), forKey: "basic")
    dropImage6.layer.addAnimation(addWaterDroppingAnimation(1.0), forKey: "basic")
}

}

Answer 1

您不应该在viewDidLoad中执行动画，因为它刚刚初始化并且还没有超视图，因此动画不起作用。尝试将代码移动到viewDidAppear中。