【发布时间】：2019-07-20 13:26:00
【问题描述】：
我在控制台中收到以下自动布局警告：
2019-09-01 21:26:03.225576+0200 Hortus[85622:2386450] [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.
(
"<NSLayoutConstraint:0x600002d16990 UILabel:0x7fc9eb816f50'Testen'.centerX == _UINavigationBarModernPromptView:0x7fc9ebe27780.centerX (active)>",
"<NSLayoutConstraint:0x600002d15c20 UILabel:0x7fc9eb816f50'Testen'.leading >= UILayoutGuide:0x6000037571e0'UIViewLayoutMarginsGuide'.leading (active)>",
"<NSLayoutConstraint:0x600002d10ff0 '_UITemporaryLayoutWidth' _UINavigationBarModernPromptView:0x7fc9ebe27780.width == 0 (active)>",
"<NSLayoutConstraint:0x600002d16a30 'UIView-leftMargin-guide-constraint' H:|-(8)-[UILayoutGuide:0x6000037571e0'UIViewLayoutMarginsGuide'](LTR) (active, names: '|':_UINavigationBarModernPromptView:0x7fc9ebe27780 )>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600002d15c20 UILabel:0x7fc9eb816f50'Testen'.leading >= UILayoutGuide:0x6000037571e0'UIViewLayoutMarginsGuide'.leading (active)>
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.
2019-09-01 21:26:03.226198+0200 Hortus[85622:2386450] [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.
(
"<NSLayoutConstraint:0x600002d16990 UILabel:0x7fc9eb816f50'Testen'.centerX == _UINavigationBarModernPromptView:0x7fc9ebe27780.centerX (active)>",
"<NSLayoutConstraint:0x600002d15540 UILabel:0x7fc9eb816f50'Testen'.trailing <= UILayoutGuide:0x6000037571e0'UIViewLayoutMarginsGuide'.trailing (active)>",
"<NSLayoutConstraint:0x600002d10ff0 '_UITemporaryLayoutWidth' _UINavigationBarModernPromptView:0x7fc9ebe27780.width == 0 (active)>",
"<NSLayoutConstraint:0x600002d14320 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x6000037571e0'UIViewLayoutMarginsGuide']-(8)-|(LTR) (active, names: '|':_UINavigationBarModernPromptView:0x7fc9ebe27780 )>"
"<NSAutoresizingMaskLayoutConstraint:0x60000043be30 h=--& v=--& _UINavigationBarModernPromptView:0x7fb3c6416640.width == 0 (active)>",
"<NSLayoutConstraint:0x600000421400 UILabel:0x7fb3c66d8bf0'Plant guide'.centerX == _UINavigationBarModernPromptView:0x7fb3c6416640.centerX (active)>",
"<NSLayoutConstraint:0x600000421f90 UILabel:0x7fb3c66d8bf0'Plant guide'.trailing <= UILayoutGuide:0x600001e58fc0'UIViewLayoutMarginsGuide'.trailing (active)>",
"<NSLayoutConstraint:0x600000421e00 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x600001e58fc0'UIViewLayoutMarginsGuide']-(20)-|(LTR) (active, names: '|':_UINavigationBarModernPromptView:0x7fb3c6416640 )>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600002d15540 UILabel:0x7fc9eb816f50'Testen'.trailing <= UILayoutGuide:0x6000037571e0'UIViewLayoutMarginsGuide'.trailing (active)>
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.
这些警告是针对导航栏中的提示给出的，但我没有为导航栏设置自动布局约束。这应该由IOS自己处理。
如何解决这些警告？
[编辑] 当连接到视图控制器时，prepare() 中会给出警告。我在prepare() 中设置了提示。 segue 是一个故事板参考，并被定义为“模态呈现”。故事板参考引用了 UINavigationController。提示设置在导航控制器的根视图控制器上。
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let identifier = segue.identifier {
switch identifier {
case "editImage":
let nc = segue.destination as? TTImageNavigationController
if let rvc = nc?.rootViewController as? TTImageEditorController {
rvc.navigationItem.prompt = navigationItem.prompt
}
default:
break
}
}
}
[编辑] 似乎大多数反应的人都不清楚这个问题。再次......我没有在代码或情节提要中设置任何自动布局设置。在 segue 之前的 prepare() 函数中设置提示后，导航栏出现问题。上面给出了代码。任何说我必须更改或检查我的约束的反应都没有帮助，因为没有要检查的约束！
[编辑] 应 Mohsen 的要求，我在 github 上创建了一个小示例项目：https://bitbucket.org/Leontien/navigationbarautolayoutwarning/src/master/
【问题讨论】：
-
您能否提供更多代码，因为这在很多情况下都会出现？
-
我不确定您希望看到哪些额外的代码。在代码中，我只设置了提示：viewController.navigationItem.prompt = "Plant guide"。导航栏添加到情节提要中并且不包含提示，因为提示是通过编程设置的。
-
@Leontien 您的日志只是列表约束，不包含任何警告，请添加更多日志。我没有出现在我的机器上。
-
@Thanh，我在问题中添加了完整的近期警告记录
-
什么版本的 Xcode / iOS？
标签： ios swift autolayout uinavigationbar