iOS 使用Masonry出现约束警告定位视图

在使用Masonry时候，有时候虽然界面显示正常，但是log里面会出现如下类似的警告。

一.问题描述：

[LayoutConstraints] 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. 

[

,

,

]

Will attempt to recover by breaking constraint 

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

The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in may also be helpful.

二. 解决方法：

1.通过断点找到有问题的控件XX

2. 初始化控件XX 下面 添加 代码   MASAttachKeys(控件XX)， 可以传多个控件

3.run，看log

可以显示出控件的名字，一目了然就可以看到有问题的控件约束，修改即可。

布局太复杂， 不好确认是哪个空间， 还有一种方法

1.先点击Debug View Hierarchy

2.打印页控件层级和地址

OC使用

po [[UIWindow keyWindow] _autolayoutTrace]

Swift使用 

expr -l objc++ -O -- [[UIWindow keyWindow] _autolayoutTrace]

3.搜索报错的地址0x111e168f0，定位到错误控件 

断点小技巧：

链接：https://www.jianshu.com/p/838b012f12a0

https://www.jianshu.com/p/5c231afb91fa