NSAutoresizingMaskLayoutConstrai

经常遇到NSAutoresizingMaskLayoutConstraint 问题 今天这个比较特殊

2019-10-29 10:10:59.130454+0800 TimeDB[75864:2625314] [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. 
    (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    <NSAutoresizingMaskLayoutConstraint:0x600002f0a620 _UIToolbarContentView:0x7fb94783d340.width == 0>,
    <NSLayoutConstraint:0x600002f335c0 _UIButtonBarStackView:0x7fb94783de50.leading == _UIToolbarContentView:0x7fb94783d340.leading>,
    <NSLayoutConstraint:0x600002f33610 _UIButtonBarStackView:0x7fb94783de50.trailing == _UIToolbarContentView:0x7fb94783d340.trailing>,
    <NSLayoutConstraint:0x600002f098b0 _UIModernBarButton:0x7fb945651f20.leading == _UIButtonBarButton:0x7fb945651340.leading + 8>,
    <NSLayoutConstraint:0x600002f09900 _UIButtonBarButton:0x7fb945651340.trailing == _UIModernBarButton:0x7fb945651f20.trailing>,
    <NSLayoutConstraint:0x600002f09d60 UILayoutGuide:0x600003569c00.leading == UIView:0x7fb945650e60.leading>,
    <NSLayoutConstraint:0x600002f09ef0 UILayoutGuide:0x600003569c00.trailing == _UIButtonBarButton:0x7fb945651340.trailing>,
    <NSLayoutConstraint:0x600002f09f40 UIView:0x7fb94783bee0.leading == UIView:0x7fb945650e60.trailing>,
    <NSLayoutConstraint:0x600002f09f90 UIView:0x7fb9456511e0.leading == UIView:0x7fb94783bee0.trailing>,
    <NSLayoutConstraint:0x600002f09fe0 _UIButtonBarButton:0x7fb945651340.leading == UIView:0x7fb9456511e0.trailing>,
    <NSLayoutConstraint:0x600002f333e0 UILayoutGuide:0x600003569c00.left == _UIButtonBarStackView:0x7fb94783de50.left>,
    <NSLayoutConstraint:0x600002f33480 _UIButtonBarStackView:0x7fb94783de50.right == UILayoutGuide:0x600003569c00.right>,
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x600002f09900 _UIButtonBarButton:0x7fb945651340.trailing == _UIModernBarButton:0x7fb945651f20.trailing>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.

提示系统帮忙移除了<NSLayoutConstraint:0x600002f09900 _UIButtonBarButton:0x7fb945651340.trailing == _UIModernBarButton:0x7fb945651f20.trailing>，但是对这两类不熟，不清楚是哪里。
XCode自带的布局预览不好调试，总在某一个页面报错，看样子是导航栏的问题，但注释掉很多都不起作用，一遍遍去看UINavigationBar的层级，最后注释掉了键盘弹起，才发现是IQKeyboardManager的问题，更新了下版本发现还有，应该是toolBar的布局没写好，fork下来，修复，给IQKeyboardManager提个issue，完事。

总结下

用来打印window下的所有视图层级，有时候应该挺实用的。

po [[UIWindow keyWindow] _autolayoutTrace]

另外expr 命令用来给地址对应的对象赋值， 比如：

expr ((UIView*) 0x7fb94783de50).backgroungColor = [UIColor blackColor]

应该也是常见的命令了，用起来这么生疏，惭愧惭愧。其实也不是什么大问题，写出来这些是因为平时遇到一些疑难杂症时都会下意识的乱试一通，今天又是如此。到头来其实效率是很差的，在试A方案的时候就想会不会是别的问题，好像知道原因了，然后中断去试，然后发现不行后又去试C方案，到头来哪个方案都没有完整的走完。有时候碰巧解决了心里感觉是哪块的问题最终也不太确定，表现出来的就是：这东西做过，但具体学到了什么，能提炼出来的就很少。

以后遇到问题该列出几个大致可能的方向来依次去试，尤其是一些常见的小问题，往往对应着很深的知识。细细想下，伴随了五六年的小问题其实也不是什么小问题了。解决过程中要有自我存在感，过程感，要极其明确是自己在解决问题而不是任由问题牵着鼻子走，不能急躁，解决问题不是目的，目地是能讲出来问题怎么发生，自己如何判断，过程中又偏向哪些方向，要着力去记下这些东西，最后问题解决后应该花时间去总结，即便不写出来也改认真的从头到尾想一遍。

真正的成果都在这里。