布局问题：Assertion failure in -[MASViewConstraint addConstraintWithLayoutAttribute:], /ss/Pods/Masonry/Masonry/MASViewConstraint.m:207

] *** Assertion failure in -[MASViewConstraint addConstraintWithLayoutAttribute:], /ss/Pods/Masonry/Masonry/MASViewConstraint.m:207

selectLabel.mas_makeConstraints { (make) -> Void in           
        make.centerY.equalTo()(selectBtn)    
        make.left.equalTo()
(selectLabel.mas_right).width().offset()(30)   
         make.right.equalTo()(self.kSelectView)

        }

  make.left.equalTo()(selectLabel.mas_right).with().offset()(30)

经常把with()写成width().
一般会crash掉，看到是布局问题，左边，线程中调试。