AutoLayout----Unable to simultaneously satisfy constraints

顺便提一下
用AutoLayout有时候会出现
Unable to simultaneously satisfy constraints. 怎么查找到底是哪里的限制出问题了呢
我们来看看打印出来的提示



但是如果你的界面很多，就比较难知道在那个界面出问题了

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.



打断点后哪里有冲突 程序就会crash
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
或者用这个category来debug
@interface UIView (UIConstraintBasedLayoutDebugging)

另外instrument里面有个CocoaLayout可以用来检测