iOS布局约束常见打印问题

自动布局常见约束错误打印：

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. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)

一般就两个原因：

1，你的约束的确设置错误；

2，忘记设置控件的：setTranslatesAutoresizingMaskIntoConstraints 等于NO 。