ios - 如何调试自动布局约束？

Question

我是 iOS 开发新手。每当我运行我的应用程序时，我都会收到此冲突约束错误。您能给我一些关于如何调试此问题的建议吗？

2016-07-13 12:53:51.186 Calculator[4458:50017] 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. 
(
    "<_UILayoutSupportConstraint:0x7fcaf3c5e670 V:[_UILayoutGuide:0x7fcaf3c62a80(0)]>",
    "<_UILayoutSupportConstraint:0x7fcaf3c5c060 _UILayoutGuide:0x7fcaf3c62a80.bottom == UIView:0x7fcaf3c54390.bottom>",
    "<NSLayoutConstraint:0x7fcaf3c54b00 UIImageView:0x7fcaf3c54c70.width == UIImageView:0x7fcaf3c54c70.height>",
    "<NSLayoutConstraint:0x7fcaf3c633d0 V:|-(0)-[UIImageView:0x7fcaf3c54c70]   (Names: '|':UIView:0x7fcaf3c54390 )>",
    "<NSLayoutConstraint:0x7fcaf3c63420 H:[UIImageView:0x7fcaf3c54c70]-(0)-|   (Names: '|':UIView:0x7fcaf3c54390 )>",
    "<NSLayoutConstraint:0x7fcaf3c63470 H:|-(0)-[UIImageView:0x7fcaf3c54c70]   (Names: '|':UIView:0x7fcaf3c54390 )>",
    "<NSLayoutConstraint:0x7fcaf3c63560 V:[UIImageView:0x7fcaf3c54c70]-(0)-[_UILayoutGuide:0x7fcaf3c62a80]>",
    "<NSLayoutConstraint:0x7fcaf3c67e50 'UIView-Encapsulated-Layout-Height' V:[UIView:0x7fcaf3c54390(736)]>",
    "<NSLayoutConstraint:0x7fcaf3c61230 'UIView-Encapsulated-Layout-Width' H:[UIView:0x7fcaf3c54390(414)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7fcaf3c54b00 UIImageView:0x7fcaf3c54c70.width == UIImageView:0x7fcaf3c54c70.height>

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.

Answer 1

似乎您添加了一个约束，而另一个约束正在抵消该约束。

通常，如果您右键单击，您就可以获得“建议的约束”，尝试使用它们，看看它是否有效!

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