XIb中使用tableview报错UIViewAlertForU

1.使用断点工具并不能找出错误，最后仔细看了下报错信息

2.报错信息

[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. 
(
    "<NSLayoutConstraint:0x608000098a60 UIView:0x7fcb7b428fe0.height == 50   (active)>",
    "<NSLayoutConstraint:0x608000098060 V:|-(0)-[UIView:0x7fcb7b428fe0]   (active, names: '|':UITableViewCellContentView:0x7fcb7b42bd40 )>",
    "<NSLayoutConstraint:0x608000097b60 V:[UIView:0x7fcb7b42ed00]-(0)-|   (active, names: '|':UITableViewCellContentView:0x7fcb7b42bd40 )>",
    "<NSLayoutConstraint:0x608000097c00 V:[UIView:0x7fcb7b428fe0]-(0)-[UIView:0x7fcb7b42ed00]   (active)>",
    "<NSLayoutConstraint:0x60000009bf80 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x7fcb7b42bd40.height == 49.5   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x608000098a60 UIView:0x7fcb7b428fe0.height == 50   (active)>

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.

3.分析

 "<NSLayoutConstraint:0x608000098a60 UIView:0x7fcb7b428fe0.height == 50   (active)>",
"<NSLayoutConstraint:0x60000009bf80 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x7fcb7b42bd40.height == 49.5   (active)>"

第一句代码信息是视图中有个界面的高度为50;
第二句中意思是cell_contentView的高度为49.5;

问题就来了

contentView没有我设置的自视图大，而且我对cell设置了clips to view = YES。
约束就存在了冲突，xcode报错提示。

把cell的高度调大或者view的高度调小解决

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