我在调试器日志中看到一个错误：
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x191f0920 H:[MPKnockoutButton:0x17a876b0]-(34)-[MPDetailSlider:0x17a8bc50](LTR)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
我该如何接听电话？它没有出现在我的代码中的任何地方。
这篇文章帮了我很多！
我使用建议的操作添加了UIViewAlertForUnsatisfiableConstraints符号断点：
Obj-C项目
po [[UIWindow keyWindow] _autolayoutTrace]
斯威夫特项目
expr -l objc++ -O -- [[UIWindow keyWindow] _autolayoutTrace]
有了这个提示，日志变得更加详细，并且对于我来说更容易确定哪个视图打破了约束。
UIWindow:0x7f88a8e4a4a0
| UILayoutContainerView:0x7f88a8f23b70
| | UINavigationTransitionView:0x7f88a8ca1970
| | | UIViewControllerWrapperView:0x7f88a8f2aab0
| | | | •UIView:0x7f88a8ca2880
| | | | | *UIView:0x7f88a8ca2a10
| | | | | | *UIButton:0x7f88a8c98820'Archived'
| | | | | | | UIButtonLabel:0x7f88a8cb0e30'Archived'
| | | | | | *UIButton:0x7f88a8ca22d0'Download'
| | | | | | | UIButtonLabel:0x7f88a8cb04e0'Download'
| | | | | | *UIButton:0x7f88a8ca1580'Deleted'
| | | | | | | UIButtonLabel:0x7f88a8caf100'Deleted'
| | | | | *UIView:0x7f88a8ca33e0
| | | | | *_UILayoutGuide:0x7f88a8ca35b0
| | | | | *_UILayoutGuide:0x7f88a8ca4090
| | | | | _UIPageViewControllerContentView:0x7f88a8f1a390
| | | | | | _UIQueuingScrollView:0x7f88aa031c00
| | | | | | | UIView:0x7f88a8f38070
| | | | | | | UIView:0x7f88a8f381e0
| | | | | | | | •UIView:0x7f88a8f39fa0, MISSING HOST CONSTRAINTS
| | | | | | | | | *UIButton:0x7f88a8cb9bf0'Retrieve data'- AMBIGUOUS LAYOUT for UIButton:0x7f88a8cb9bf0'Retrieve data'.minX{id: 170}, UIButton:0x7f88a8cb9bf0'Retrieve data'.minY{id: 171}
| | | | | | | | | *UIImageView:0x7f88a8f3ad80- AMBIGUOUS LAYOUT for UIImageView:0x7f88a8f3ad80.minX{id: 172}, UIImageView:0x7f88a8f3ad80.minY{id: 173}
| | | | | | | | | *App.RecordInfoView:0x7f88a8cbe530- AMBIGUOUS LAYOUT for App.RecordInfoView:0x7f88a8cbe530.minX{id: 174}, App.RecordInfoView:0x7f88a8cbe530.minY{id: 175}, App.RecordInfoView:0x7f88a8cbe530.Width{id: 176}, App.RecordInfoView:0x7f88a8cbe530.Height{id: 177}
| | | | | | | | | | +UIView:0x7f88a8cc1d30- AMBIGUOUS LAYOUT for UIView:0x7f88a8cc1d30.minX{id: 178}, UIView:0x7f88a8cc1d30.minY{id: 179}, UIView:0x7f88a8cc1d30.Width{id: 180}, UIView:0x7f88a8cc1d30.Height{id: 181}
| | | | | | | | | | | *UIView:0x7f88a8cc1ec0- AMBIGUOUS LAYOUT for UIView:0x7f88a8cc1ec0.minX{id: 153}, UIView:0x7f88a8cc1ec0.minY{id: 151}, UIView:0x7f88a8cc1ec0.Width{id: 154}, UIView:0x7f88a8cc1ec0.Height{id: 165}
| | | | | | | | | | | | *UIView:0x7f88a8e68e10- AMBIGUOUS LAYOUT for UIView:0x7f88a8e68e10.minX{id: 155}, UIView:0x7f88a8e68e10.minY{id: 150}, UIView:0x7f88a8e68e10.Width{id: 156}
| | | | | | | | | | | | *UIImageView:0x7f88a8e65de0- AMBIGUOUS LAYOUT for UIImageView:0x7f88a8e65de0.minX{id: 159}, UIImageView:0x7f88a8e65de0.minY{id: 182}
| | | | | | | | | | | | *UILabel:0x7f88a8e69080'8-6-2015'- AMBIGUOUS LAYOUT for UILabel:0x7f88a8e69080'8-6-2015'.minX{id: 183}, UILabel:0x7f88a8e69080'8-6-2015'.minY{id: 184}, UILabel:0x7f88a8e69080'8-6-2015'.Width{id: 185}
| | | | | | | | | | | | *UILabel:0x7f88a8cc0690'16:34'- AMBIGUOUS LAYOUT for UILabel:0x7f88a8cc0690'16:34'.minX{id: 186}, UILabel:0x7f88a8cc0690'16:34'.minY{id: 187}, UILabel:0x7f88a8cc0690'16:34'.Width{id: 188}, UILabel:0x7f88a8cc0690'16:34'.Height{id: 189}
| | | | | | | | | | | | *UIView:0x7f88a8cc2050- AMBIGUOUS LAYOUT for UIView:0x7f88a8cc2050.minX{id: 161}, UIView:0x7f88a8cc2050.minY{id: 166}, UIView:0x7f88a8cc2050.Width{id: 163}
| | | | | | | | | | | | *UIImageView:0x7f88a8e69d90- AMBIGUOUS LAYOUT for UIImageView:0x7f88a8e69d90.minX{id: 190}, UIImageView:0x7f88a8e69d90.minY{id: 191}, UIImageView:0x7f88a8e69d90.Width{id: 192}, UIImageView:0x7f88a8e69d90.Height{id: 193}
| | | | | | | | | | | *UIView:0x7f88a8f3cc00
| | | | | | | | | | | | *UIView:0x7f88a8e618d0
| | | | | | | | | | | | *UIImageView:0x7f88a8e5ba10
| | | | | | | | | | | | *UIView:0x7f88a8f3cd70
| | | | | | | | | | | | *UIImageView:0x7f88a8e58e10
| | | | | | | | | | | | *UIImageView:0x7f88a8e5e7a0
| | | | | | | | | | | | *UIView:0x7f88a8f3cee0
| | | | | | | | | | | *UIView:0x7f88a8f3dc70
| | | | | | | | | | | | *UIView:0x7f88a8e64dd0
| | | | | | | | | | | | *UILabel:0x7f88a8e65290'Average flow rate'
| | | | | | | | | | | | *UILabel:0x7f88a8e712d0'177.0 ml/s'
| | | | | | | | | | | | *UILabel:0x7f88a8c97150'1299.4'
| | | | | | | | | | | | *UIView:0x7f88a8f3dde0
| | | | | | | | | | | | *UILabel:0x7f88a8f3df50'Maximum flow rate'
| | | | | | | | | | | | *UILabel:0x7f88a8cbfdb0'371.6 ml/s'
| | | | | | | | | | | | *UILabel:0x7f88a8cc0230'873.5'
| | | | | | | | | | | | *UIView:0x7f88a8f3e2a0
| | | | | | | | | | | | *UILabel:0x7f88a8f3e410'Total volume'
| | | | | | | | | | | | *UILabel:0x7f88a8cc0f20'371.6 ml'
| | | | | | | | | | | | *UIView:0x7f88a8f3e870
| | | | | | | | | | | | *UILabel:0x7f88a8f3ea00'Time do max. flow'
| | | | | | | | | | | | *UILabel:0x7f88a8cc0ac0'3.6 s'
| | | | | | | | | | | | *UIView:0x7f88a8f3ee10
| | | | | | | | | | | | *UILabel:0x7f88a8f3efa0'Flow time'
| | | | | | | | | | | | *UILabel:0x7f88a8cbf980'2.1 s'
| | | | | | | | | | | | *UIView:0x7f88a8f3f3e0
| | | | | | | | | | | | *UILabel:0x7f88a8f3f570'Voiding time'
| | | | | | | | | | | | *UILabel:0x7f88a8cc17e0'3.5 s'
| | | | | | | | | | | | *UIView:0x7f88a8f3f9a0
| | | | | | | | | | | | *UILabel:0x7f88a8f3fb30'Voiding delay'
| | | | | | | | | | | | *UILabel:0x7f88a8cc1380'1.0 s'
| | | | | | | | | | | | *UIView:0x7f88a8e65000
| | | | | | | | | | | | *UIButton:0x7f88a8e52f20'Show'
| | | | | | | | | | | | *UIImageView:0x7f88a8e6e1d0
| | | | | | | | | | | | *UIButton:0x7f88a8e52c90'Send'
| | | | | | | | | | | | *UIImageView:0x7f88a8e61bb0
| | | | | | | | | | | | *UIButton:0x7f88a8e528e0'Delete'
| | | | | | | | | | | | *UIImageView:0x7f88a8e6b3f0
| | | | | | | | | | | | *UIView:0x7f88a8f3ff60
| | | | | | | | | *UIActivityIndicatorView:0x7f88a8cba080
| | | | | | | | | | UIImageView:0x7f88a8cba700
| | | | | | | | | *_UILayoutGuide:0x7f88a8cc3150
| | | | | | | | | *_UILayoutGuide:0x7f88a8cc3b10
| | | | | | | UIView:0x7f88a8f339c0
| | UINavigationBar:0x7f88a8c96810
| | | _UINavigationBarBackground:0x7f88a8e45c00
| | | | UIImageView:0x7f88a8e46410
| | | UINavigationItemView:0x7f88a8c97520'App'
| | | | UILabel:0x7f88a8c97cc0'App'
| | | UINavigationButton:0x7f88a8e3e850
| | | | UIImageView:0x7f88a8e445b0
| | | _UINavigationBarBackIndicatorView:0x7f88a8f2b530
Legend:
* - is laid out with auto layout
+ - is laid out manually, but is represented in the layout engine because translatesAutoresizingMaskIntoConstraints = YES
• - layout engine host
然后我暂停执行， 
并通过命令更改了有问题的视图的背景颜色（当然，替换0x7f88a8cc2050为您对象的内存地址）...
对象
expr ((UIView *)0x7f88a8cc2050).backgroundColor = [UIColor redColor]
斯威夫特3.0
expr -l Swift -- import UIKit
expr -l Swift -- unsafeBitCast(0x7f88a8cc2050, to: UIView.self).backgroundColor = UIColor.red
...和结果太棒了！
简直太神奇了！希望能帮助到你。
您需要添加一个Symbolic Breakpoint。Apple提供了有关如何执行此操作的出色指南。
- 打开Breakpoint Navigator
cmd+7（cmd+8在Xcode 9中） - 点击
Add左下角的按钮 - 选择
Add Symbolic Breakpoint... - 它说
Symbol只要输入UIViewAlertForUnsatisfiableConstraints
您还可以将其像其他任何断点一样对待，将其打开和关闭，添加操作或记录消息。
遵循斯蒂芬的建议，并尝试调试代码，哇！有效。答案在于调试消息本身。
Will attempt to recover by breaking constraint
NSLayoutConstraint:0x191f0920 H:[MPKnockoutButton:0x17a876b0]-(34)-[MPDetailSlider:0x17a8bc50](LTR)>
上面的行告诉您，运行时通过删除此约束而起作用。可能是您不需要按钮（MPKnockoutButton）上的水平间距。清除此约束后，它将在运行时不会抱怨，并且您将获得所需的行为。
每当我尝试删除系统必须打破的约束时，我的约束就不再足以满足IB（即IB中显示的“缺失约束”，这意味着它们是不完整的，将不会使用）。我实际上是通过将要打破的约束设置为低优先级来解决此问题的（这是一个假设），该约束使系统可以优雅地打破约束。它可能不是最好的解决方案，但它解决了我的问题，并且所产生的约束条件完美地发挥了作用。
本文地址：http://ios.askforanswer.com/ruhebuhuouiviewalertforunsatisfiableconstraints.html
文章标签：autolayout , constraints , ios , uikit , xcode7
版权声明：本文为原创文章，版权归 admin 所有，欢迎分享本文，转载请保留出处！
文章标签：autolayout , constraints , ios , uikit , xcode7
版权声明：本文为原创文章，版权归 admin 所有，欢迎分享本文，转载请保留出处！
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