如何在 iOS 中使用 swift 重新定位视图？

Posted 2023-03-15

【中文标题】如何在 iOS 中使用 swift 重新定位视图？

【英文标题】：How to reposition view using swift in iOS?

【发布时间】：2015-03-13 11:16:49

【问题描述】：

我正在使用故事板为我的应用程序构建 ui 并使用 swift 并且我准备了以下布局，您可以在屏幕截图中看到。

我想隐藏包含 stop1 详细信息的视图，并在运行时将 stop2 视图替换为 stop1。

我正在使用以下代码来隐藏 stop1 和更新 stop2 的约束

    stop1Frame.hidden = true
    stop2Frame.updateConstraints()

请帮帮我。

将高度限制设置为 stop1 的 0 有效，但在控制台中显示以下错误。

 2015-03-13 17:03:52.738 GroundSpan[5392:1777378] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
    (
    "<NSLayoutConstraint:0x7a644500 V:[UILabel:0x7a643d50'Please tap on + button to...'(63)]>",
    "<NSLayoutConstraint:0x7a64cb80 V:[UIView:0x7a63aaa0(0)]>",
    "<NSLayoutConstraint:0x7a64cc10 UILabel:0x7a632e20'Stop1'.top == UIView:0x7a63aaa0.topMargin>",
    "<NSLayoutConstraint:0x7a64d2b0 V:[UILabel:0x7a643d50'Please tap on + button to...']-(20)-|   (Names: '|':UIView:0x7a63aaa0 )>",
    "<NSLayoutConstraint:0x7a64d310 V:[UILabel:0x7a632e20'Stop1']-(NSSpace(8))-[UILabel:0x7a643d50'Please tap on + button to...']>")

Will attempt to recover by breaking constraint 

<NSLayoutConstraint:0x7a644500 V:[UILabel:0x7a643d50'Please tap on + button to...'(63)]>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2015-03-13 17:03:52.739 GroundSpan[5392:1777378] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSLayoutConstraint:0x7a64cb80 V:[UIView:0x7a63aaa0(0)]>",
    "<NSLayoutConstraint:0x7a64cc10 UILabel:0x7a632e20'Stop1'.top == UIView:0x7a63aaa0.topMargin>",
    "<NSLayoutConstraint:0x7a64d2b0 V:[UILabel:0x7a643d50'Please tap on + button to...']-(20)-|   (Names: '|':UIView:0x7a63aaa0 )>",
    "<NSLayoutConstraint:0x7a64d310 V:[UILabel:0x7a632e20'Stop1']-(NSSpace(8))-[UILabel:0x7a643d50'Please tap on + button to...']>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7a64d310 V:[UILabel:0x7a632e20'Stop1']-(NSSpace(8))-[UILabel:0x7a643d50'Please tap on + button to...']>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

【问题讨论】：

你的 Swift 代码在哪里？

添加了我用来隐藏和更新约束的快速代码

【参考方案1】：

为 stop1 的高度约束创建一个IBOutlet，以便您可以在代码中访问它。

要隐藏 stop1，请将其高度约束设置为 0，这样 stop2 会向上移动。

@IBOutlet weak var stop1HeightConstraint: NSLayoutConstraint!
...

// in your function:
self.stop1HeightConstraint.constant = 0

UIView.animateWithDuration(0.4, animations: 
    self.view.layoutIfNeeded()
)

这一切都假定您已正确设置自动布局和约束。

【讨论】：

您的技巧使 stop2 重新定位以代替 stop1，但在控制台中出现错误，请查看已编辑的问题以获取错误日志。

这就是我在回答的最后一句话中的意思：您的约束需要正确设置。我们看不到您如何设置约束。白框应该是 UIView，其中的标签和按钮应该相对于该父视图定位。

我没有看到任何红线或黄线每件事都是完美的蓝色，这意味着所有约束都设置得很好。但仍然收到此消息。