试图在swift中动画化一个约束 [英] trying to animate a constraint in swift

问题描述

我有一个UITextField，我想放大它的宽度，当点击。我设置约束，并确保左侧的约束具有较低的优先级，那么我试图在右侧动画。

这里是代码

  //移动输入框
 UIView.animateWithDuration（10.5，animations：{ 
 self.nameInputConstraint.constant = 8 
}，完成：
中的
（值：Bool）println（>>> move const）
}）
  

这可以工作，但似乎只是瞬间发生，似乎没有任何运动。我尝试设置它10秒，以确保我没有丢失任何东西，但我有相同的结果。

nameInputConstraint是我控制的约束的名称拖动

解决方案

div>

您需要先更改约束，然后对更新进行动画处理。

  self.nameInputConstraint.constant = 8 
 UIView.animateWithDuration（0.5）{
 self.view。 layoutIfNeeded（）
} 
  

在Swift 3.0中：

  UIView.animate（withDuration：0.5）{
 self.view.layoutIfNeeded（）
} 
  

I have an UITextField that I want to enlarge it's width when tapped on. I set up the constraints and made sure the constraint on the left has the lower priority then the one that I am trying to animate on the right side.

Here is the code that I am trying to use.

  // move the input box
    UIView.animateWithDuration(10.5, animations: {
        self.nameInputConstraint.constant = 8
        }, completion: {
            (value: Bool) in
            println(">>> move const")
    })

This works, but it seems to just happen instantly and there doesn't seem to be any movement. I tried to set it 10 seconds to make sure I wasn't missing anything, but I got the same results.

nameInputConstraint is the name of the constraint that I control dragged to connect into my class from IB.

Thanks for your help in advance!

解决方案

You need to first change the constraint and then animate the update.

self.nameInputConstraint.constant = 8
UIView.animateWithDuration(0.5) {
    self.view.layoutIfNeeded()
}

And in Swift 3.0:

UIView.animate(withDuration: 0.5) {
    self.view.layoutIfNeeded()
}

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