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 。
