UIView.animateWithDuration没有动画 [英] UIView.animateWithDuration not animating

问题描述

我的ViewController viewDidLoad函数中的UIView.animateWithDuration调用没有动画。立即调用完成块。 println输出显示'completion true'。 viewDidLoad函数是否放置了我的启动动画的错误位置？非常感谢任何提示。

The UIView.animateWithDuration call in my ViewController viewDidLoad function does not animate. The completion block gets called immediately. The println output shows 'completion true'. Is the viewDidLoad function the wrong place to put my startup animation? Any hints are greatly appreciated.

class ViewController: UIViewController {
    @IBOutlet var beatIndicator:UIView?

    override func viewDidLoad() {
        super.viewDidLoad()

        if let led = beatIndicator? {
            led.alpha = 1.0
            led.frame = CGRectMake(20, 20, 30, 30)
            led.layer.cornerRadius = 15

            UIView.animateWithDuration(3.0, animations:{
                led.alpha = 0.5
                led.frame = CGRectMake(25, 25, 20, 20)
                led.layer.cornerRadius = 10
            }, completion:{(value: Bool) in
                println("completion \(value)")
            })
        }

        // ...
    }
}

推荐答案

你试过吗？把它放在ViewDidAppear？

Have you tried putting it in ViewDidAppear?

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        if let led = beatIndicator? {
            led.alpha = 1.0
            led.frame = CGRectMake(20, 20, 30, 30)
            led.layer.cornerRadius = 15

            UIView.animateWithDuration(3.0, animations:{
                led.alpha = 0.5
                led.frame = CGRectMake(25, 25, 20, 20)
                led.layer.cornerRadius = 10
            }, completion:{(value: Bool) in
                println("completion \(value)")
            })
        }

        // ...
    }

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