在Swift中运行时更改受自动布局约束的UIView的框架 [英] Changing an Autolayout-constrained UIView's frame at runtime in Swift

问题描述

例如，我使用此代码来更改名为Propo的UIView的帧位置:

For example, I use this code to change the frame position of a UIView called Propo:

        self.Propo.frame.origin.x -= self.view.frame.width

(Propo在分镜脚本中有约束)

(Propo has constraints in Storyboard)

但是，当应用视图消失并重新出现时，UIView会将其自身重置为其原始位置.我该如何解决?我希望通过编程方式更改UIView的位置.

But When the app view disappears and reappears, the UIView resets itself to its original position. How can I do to resolve it? I want the UIView to keep its position when I change it programmatically.

我尝试用updateViewConstraints()进行其他操作追加...

I've tried updateViewConstraints() by anything else append...

推荐答案

约束和手动框架操作直接冲突.您必须选择一个.相反，您应通过故事板中的@IBOutlet将Ctrl拖动到您的视图控制器上，来提升"您想要更改的约束.然后，您可以操纵其常量:

Constraints and manual frame manipulation are directly in conflict. You have to choose one or the other. You should instead "promote" the constraint you wish to change by Ctrl-dragging it to your view controller as an @IBOutlet in Storyboard. Then, you can manipulate its constant:

class MyViewController: UIViewController {
    @IBOutlet weak var myPropoLeftEdgeConstraint: NSLayoutConstraint!

    @IBAction doChangePropo(sender: AnyObject) {
        myPropoLeftEdgeConstraint.constant -= view.frame.width
        view.layoutIfNeeded()
    }
}

许多地方的目标C中已经涵盖了这一点，因此，如果您可以阅读这些示例，则只需进行搜索即可以编程方式更改代码中的NSLayoutConstraint.

This is already covered in Objective C in many places, so just do a search on programmatically changing an NSLayoutConstraint in code if you can read those examples.

如何在代码中编辑约束

(进行编辑以使其更加适用:通常应该对约束进行动画处理，以获得干净的用户体验.否则，眼睛会感到困惑.)

(Edit to make more applicable: generally constraints should be animated for a clean user experience. Otherwise the eye is confused.)

通过将view.layoutIfneeded包装在UIView.animateWithDuration(duration) { ... }块中，可以轻松地为约束调整设置动画.

You can easily animate the constraint adjustment by wrapping view.layoutIfneeded in a UIView.animateWithDuration(duration) { ... } block.

这篇关于在Swift中运行时更改受自动布局约束的UIView的框架的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！