Ios7 iphone ios 7.x与ios 6.x的限制

如果用户界面在iOS 7.x上运行良好，但在iOS 6.x上会出现约束中断。想知道为什么完全相同的UI自动布局会有如此大的差异，等等

下面是iOS 6.x上的一个中断示例

Will attempt to recover by breaking constraint 

<NSLayoutConstraint:0x17e91390 V:[UIView:0x17ecb3b0]-(0)-|   (Names: '|':XxxCollectionViewCollectionViewCell:0x17eca520 )>

Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2014-07-11 11:39:33.886 XXXXX[25856:c07] 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:0x17ecaf40 h=--& v=-&& XxxCollectionViewCollectionViewCell:0x17eca520.height == 34*UICollectionView:0xe294400.height - 20740>",
"<NSAutoresizingMaskLayoutConstraint:0x1660b530 h=-&- v=-&- UINavigationTransitionView:0xbaf7b60.height == UILayoutContainerView:0xbaf6f80.height>",
"<NSAutoresizingMaskLayoutConstraint:0xd24fec0 h=-&- v=-&- UICollectionView:0xe294400.height == UIView:0x17ed5da0.height>",
"<NSAutoresizingMaskLayoutConstraint:0xd257470 h=-&- v=-&- UIViewControllerWrapperView:0xbe75e80.height == UINavigationTransitionView:0xbaf7b60.height - 64>",
"<NSAutoresizingMaskLayoutConstraint:0xd233b30 h=-&- v=-&- UIView:0x17ed5da0.height == UIViewControllerWrapperView:0xbe75e80.height>",
"<NSAutoresizingMaskLayoutConstraint:0xba5ea50 h=-&- v=-&- UILayoutContainerView:0xbaf6f80.height == VoiceTouchOverlayWindow:0xbec7fb0.height>",
"<NSAutoresizingMaskLayoutConstraint:0xba5d4b0 h=--- v=--- V:[VoiceTouchOverlayWindow:0xbec7fb0(480)]>"
)

将尝试通过破坏约束进行恢复
在objc_异常_抛出时中断，以便在调试器中捕获该异常。
中列出的UIView上UIConstraintBasedLayoutDebugging类别中的方法也可能会有所帮助。
2014-07-11 11:39:33.886 XXXXX[25856:c07]无法同时满足约束条件。
可能下面列表中至少有一个约束是您不想要的。试着这样做：（1）看看每个约束，试着找出你不期望的约束；（2） 找到添加了不需要的约束的代码，然后修复它。（注意：如果您看到不理解的NSAutoresizingMaskLayoutConstraints，请参阅UIView属性TranslatesAutoResizingMaskToConstraints的文档）
(
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)