如何捕获uiviewalertforunsatisableconstraints ?

我看到一个错误出现在我的调试器日志:

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.

我怎么能骗过那个电话?它没有出现在我的代码的任何地方。

Screenshot1

137942 次浏览
小开

你需要添加一个Symbolic Breakpoint。Apple提供了优秀的导游来说明如何做到这一点。

  1. 打开断点导航器cmd+7 (Xcode 9中的cmd+8)
  2. 单击左下角的Add按钮
  3. 选择Add Symbolic Breakpoint...
  4. 它说Symbol只需要输入UIViewAlertForUnsatisfiableConstraints

您还可以像对待任何其他断点一样对待它，打开和关闭它，添加操作或日志消息。

小开

听从Stephen的建议，尝试调试代码，哇!它工作。答案在于调试消息本身。

将尝试通过打破约束恢复 NSLayoutConstraint: 0 x191f0920 H: [MPKnockoutButton: 0 x17a876b0] - (34) [MPDetailSlider: 0 x17a8bc50] (LTR)在< /代码> < / p >

上面的代码行告诉您，运行时通过删除这个约束来工作。也许你不需要水平间距的按钮(MPKnockoutButton)。一旦你清除了这个约束，它就不会在运行时报错。你会得到想要的行为。

小开

每当我试图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“缺少约束”显示在IB中，这意味着它们是不完整的，不会被使用)。实际上，我通过将它想要打破的约束设置为低优先级来解决这个问题，这(这是一个假设)允许系统优雅地打破约束。这可能不是最好的解决方案，但它解决了我的问题，并且产生的约束非常有效。

小开
最佳答案

这个帖子帮助我很多!

我添加了UIViewAlertForUnsatisfiableConstraints符号断点和建议的操作:

Obj-C项目

po [[UIWindow keyWindow] _autolayoutTrace]

Objective-C项目中具有自定义动作的符号断点

迅速的项目

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，并且更容易识别哪个视图破坏了约束。

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Pause，我用命令改变了有问题的视图的背景颜色(当然，用你的对象的内存地址替换0x7f88a8cc2050)…

Obj-C

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

．.． 结果太棒了!

暗示视图

简单地令人惊叹!

小开

这通常出现在你想在iPad中使用UIActivityViewController时。

在呈现控制器以标记箭头之前，添加以下内容。

activityViewController.popoverPresentationController?.sourceRect = senderView.frame // senderView can be your button/view you tapped to call this VC

我猜你已经有了以下内容，如果没有，把它们加起来:

activityViewController.popoverPresentationController?.sourceView = self.view

小开

我想我的问题是当我看到这样的东西时:

(
"<NSLayoutConstraint:0x600002faf7a0 'UISV-alignment' UIStackView:0x7fcdda716770.top == UIStackView:0x7fcdda7291d0.top   (active)>",
"<NSLayoutConstraint:0x600002f84dc0 'UISV-canvas-connection' UILayoutGuide:0x6000035a8620'UIViewLayoutMarginsGuide'.top == UILabel:0x7fcdda716900.top   (active)>",
"<NSLayoutConstraint:0x600002f8dfe0 'UISV-spacing' V:[UIImageView:0x7fcdda7170c0]-(2)-[UIStackView:0x7fcdda7291d0]   (active)>",
"<NSLayoutConstraint:0x600002f84e60 'UISV-spacing' V:[UILabel:0x7fcdda716900]-(2)-[UIImageView:0x7fcdda7170c0]   (active)>",
"<NSLayoutConstraint:0x600002f84c80 'UIView-topMargin-guide-constraint' V:|-(20)-[UILayoutGuide:0x6000035a8620'UIViewLayoutMarginsGuide']   (active, names: '|':UIStackView:0x7fcdda716770 )>"
)

我猜，恶心。他们并不指望我处理这些垃圾……但也许这就是我们所能得到的，也许并没有那么糟糕。

让我们稍微分解一下，代码指的是约束的id。实际上，你可以通过像这样简单地打印约束来找出它们对应的约束:

print("my Constraint", ibOutletConstraint)

你会得到:

my Constraint Optional(<NSLayoutConstraint:0x600001625a90 UIStackView:0x7fdca0c0d1f0.width == 2*UIStackView: 0x7fcdda716770.width   (inactive)>)

现在我可以获取:0x7fcdda716770并搜索输出以将其与所讨论的约束匹配。它很乏味，当然也不迷人，但这是一种逐步打破它的方法。我认为苹果应该更清楚地说明哪个约束存在问题。


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