我正在尝试用约束为我的取消按钮设置动画，并且动画无法正常工作 [英] i am trying to animate my unbutton with a constraint and the animation is not working

问题描述

有人可以告诉我为什么这不是动画吗？我觉得代码很完美，但是动画功能不起作用。按钮立即从一侧跳到另一侧，但是就像我说的那样，它没有动画...

Can some one please tell me why this is not animating? I feel that the code is all perfect but the animate function is not working. The button is jumping instantly from side to side but like i said it isn't animating...

func moveResetButton( constraint : NSLayoutConstraint, isOffScreen : Bool)  {

    if isOffScreen {
        //animate the button onto the screen
        UIView.animate(withDuration: 3.0, delay: 0.0, options: .curveLinear, animations: {

            constraint.constant += 120

        }, completion: nil)

    } else {
        //animate the button off of the screen
        UIView.animate(withDuration: 1.0, delay: 0.0, options: .curveLinear, animations: {

            constraint.constant -= 120

        }, completion: nil)
    }
}

推荐答案

我知道了。只需在约束更改下将 self.view.layoutIfNeeded（）添加到代码中即可。工作顺利。

i figured it out. just need to add self.view.layoutIfNeeded() to the code under the constraint change. worked smoothly.

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