1.分4类写法

1.UIView

make.left.right.equalTo(lable);

2.NSNumber

make.left.right.equalTo(@20);

3.CGFloat

make.left.right.mas_equalTo(20);

4.NSArray

?

2.优先级

3.更新 删除

update remake
持有---references

4.约束冲突

ambiguous

5.调试

1.po exf13493

2. expr 00900

参考：https://juejin.im/post/5ac34f9351882555867f9f12