如何捕获UIViewAlertForUnsatisfiableConstraints？

234

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。

屏幕截图1

ios  autolayout  uikit  constraints  xcode7 
— 莫里·马克维兹（Maury Markowitz）
source
在十分之九的情况下：这仅是由于：对于yoru故事板上的某些视图或项目，您取消选中“已安装”。（例如，仅是一个开发按钮或您不需要的其他按钮。）通常，它对“未安装”的处理很差：它经常留下约束，如果没有未安装的项目，约束将变得毫无意义。通常，解决方案只是删除您遗忘的“未安装”项-删除它们即可。
— Fattie

Answers:

442

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]

Objective-C项目中具有自定义操作的符号断点

斯威夫特项目

expr -l objc++ -O -- [[UIWindow keyWindow] _autolayoutTrace]

具有自定义动作的符号断点

有了这个提示，日志变得更加详细，而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， 暂停 并使用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！

提示视图

简直太神奇了！希望能帮助到你。

— 汤玛斯·卡尔蒙（ThomásCalmon）
source
3
@iAnurag当执行暂停时，可以在控制台区域中运行命令。
— 汤玛斯·卡蒙
2
@TomCalmon我做了同样的事情……但是它显示以下错误 rror: Execution was interrupted, reason: EXC_BAD_ACCESS (code=1, address=0x7f88a8cc2050). The process has been returned to the state before expression evaluation.
— iAnurag
2
expr -l objc++ -O -- [[UIWindow keyWindow] _autolayoutTrace]nil为我归来
— Igor Andreev '18
2
确保将0x7f88a8cc2050替换为对象的内存地址，并在执行暂停时在控制台中运行命令。
— 汤姆·霍华德
3
毫不掩饰。很棒的提示，完全可以帮助我直接解决这个问题。将该项目更改为红色后，请尽可能继续执行操作，您将看到突出显示的内容。
— 亚伦
255

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。

  1. 打开Breakpoint Navigator cmd+7（cmd+8在Xcode 9中）
  2. 点击Add左下角的按钮
  3. 选择 Add Symbolic Breakpoint...
  4. 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。

— 斯蒂芬·弗拉尼（Stephen Furlani）
source
55
我只是不明白如何通过此提示更好地调试问题。我添加了一个象征性的断点，但是它仍然无法提供足够的信息，这是什么问题。唯一的方法是尝试逐行阅读并了解导致问题的原因....否则清除约束，然后再将其与asstent视图中的Preview一起添加，将对大多数人有最大的帮助！
— Alex Cio
11
这可能有助于在断点处停止后获取更多信息：staxmanade.com/2015/06/debugging-ios-autolayout-issues
— fabb
1
只需添加一下，您现在就可以直接在IB中为约束指定标识符，因此在调试它们时，便会看到该名称。
— Mark A. Donohoe
2
（随访上@MarqueIV）NSLayoutConstraint已经有一个identifier自iOS的属性7 - 的Xcode 7及以上，其可从IB故事板从代码集都很好。通过设置标识符，您可以更轻松地在调试日志中区分系统生成的约束和用户生成的约束，例如myConstraint.identifier = "centered image"（源和示例：useyourloaf.com/blog/using-identifiers-to-debug-autolayout）
— PDK
@AlexCio它如何帮助？至少它会在发生时暂停。它提供了堆栈跟踪，您可以在其中追溯并找到原点...
— Honey
10

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。可能您的按钮（MPKnockoutButton）不需要水平间距。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。

— 满足组
source
3
编译器？您是说运行时？编译器没有删除约束。编译器将其留在此处以供运行时处理，因此在运行时 “通过打破约束来恢复” 。
— drhr
是的，我指的是运行时
— Sategroup
2

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这个问题的（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，但是它解决了我的问题，并且所产生的约束条件完美地发挥了作用。

— 尼克·莫里纽克斯
source
2
通常，这是您要使用在运行时删除的占位符约束的情况。要将约束设为占位符约束，请转到约束检查器，然后单击“在构建时删除”。请注意，IB绘图区域中的约束工字钢符号如何从蓝色变为灰色以表明这一点。
— spencery2
1
我遇到过同样的问题。当我删除打破的约束时，我的设计就打破了。所以我将优先级设置为中。
— 杰里米·皮德诺埃尔
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