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我想制作一个在视图中心打招呼的应用程序，等待几秒钟并动画到顶部（有点像您在许多应用程序中看到的登录视图）

无论我尝试什么，我都无法将文本保持在 x 轴的中心。你能看看我的代码并告诉我错误是什么吗？

谢谢

    // Blur Effect
    var blurEffect = UIBlurEffect(style: UIBlurEffectStyle.Light)
    var blurEffectView = UIVisualEffectView(effect: blurEffect)
    blurEffectView.frame = view.bounds
    view.addSubview(blurEffectView)

    // Vibrancy Effect
    var vibrancyEffect = UIVibrancyEffect(forBlurEffect: blurEffect)
    var vibrancyEffectView = UIVisualEffectView(effect: vibrancyEffect)
    vibrancyEffectView.frame = view.bounds

    // Add label to the vibrancy view

    vibrancyEffectView.contentView.addSubview(vibrantLabel)

    vibrantLabel.textAlignment = NSTextAlignment.Center


    // Add the vibrancy view to the blur view
    blurEffectView.contentView.addSubview(vibrancyEffectView)


    UIView.animateWithDuration(1, delay: 1, options: .CurveEaseIn, animations: {() -> Void in

        self.vibrantLabel.frame = CGRectMake(0, 100, self.vibrantLabel.frame.width, self.vibrantLabel.frame.height)
        }, completion: {(finished: Bool) -> Void in
            self.view.alpha = 1
    })
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2 回答 2

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找到了解决方案。我需要在 viewDidLayoutSubviews() 中设置初始位置，然后在 viewDidAppear() 中设置动画

@IBOutlet var vibrantLabel: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()
    // Blur Effect

    var blurEffect = UIBlurEffect(style: UIBlurEffectStyle.Light)
    var blurEffectView = UIVisualEffectView(effect: blurEffect)
    blurEffectView.frame = view.bounds
    view.addSubview(blurEffectView)

    // self.vibrantLabel.layer.anchorPoint = (CGPointMake(-0.25, -2.65))

    // Vibrancy Effect
    var vibrancyEffect = UIVibrancyEffect(forBlurEffect: blurEffect)
    var vibrancyEffectView = UIVisualEffectView(effect: vibrancyEffect)
    vibrancyEffectView.frame = view.bounds

    // Add label to the vibrancy view

    view.addSubview(vibrantLabel)

    vibrantLabel.textAlignment = NSTextAlignment.Center

    // Add the vibrancy view to the blur view
    blurEffectView.contentView.addSubview(vibrancyEffectView)

}

override func viewDidLayoutSubviews() {


    vibrantLabel.center = CGPointMake(view.frame.midX, view.frame.midY)

}

override func viewDidAppear(animated: Bool) {

    UILabel.animateWithDuration(1.25, delay: 1, options: .CurveEaseInOut, animations: {

        self.vibrantLabel.center = CGPointMake(self.view.frame.midX, 100)

        }) { (Bool) in

            print("success")

    }


}
于 2016-04-12T19:38:05.133 回答
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要解决您的问题，只需在动画期间保留标签的 x 原点即可。请尝试这一行：

self.vibrantLabel.frame = CGRectMake(self.vibrantLabel.frame.origin.x, 100, self.vibrantLabel.frame.width, self.vibrantLabel.frame.height)

您将 x 轴上的原点设置为零，因此您的标签动画左对齐与其父视图。

于 2016-04-12T08:32:19.540 回答