出现键盘时IOS App Layout Constraint Errors

Question

我已经构建了一个带有单个 View Controller 的简单混合应用程序，其中我放置了一个加载嵌入式 HTM5L/CSS/JS Web 应用程序的 UIWebView。

每当我的应用程序运行并且 WebView 需要用户输入时，屏幕键盘就会出现， WebView 缩小到键盘上方的剩余空间，用户输入文本，按下“完成”，屏幕键盘就会消失。对用户来说，该应用程序运行良好。

然而，在 XCode 控制台上，有大量错误被复制到下面的问题中。据我所知，这些错误在 XCode 9 之前不存在，至少我从未注意到它们，我想我会给出它们的大小。

非常感谢有关如何解决这些错误的任何帮助。您可以很正确地说，阅读错误消息，但是我已经这样做了一段时间，让我感到困惑的是我没有任何 UIButtonBars 也没有任何 UIToolBars
谢谢。

<_UIKBCompatInputView: 0x10be39850; frame = (0 0; 0 0); layer = <CALayer: 0x1c0024be0>> returned 0 width, assuming UIViewNoIntrinsicMetric
2018-07-12 16:42:30.828370+0100 MyApp[3763:346405] API error: <_UIKBCompatInputView: 0x10be39850; frame = (0 0; 0 0); layer = <CALayer: 0x1c0024be0>> returned 0 width, assuming UIViewNoIntrinsicMetric
2018-07-12 16:42:30.873906+0100 MyApp[3763:346405] [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. 
    (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x1c0284380 h=-&- v=-&- _UIToolbarContentView:0x10be1e090.width == UIToolbar:0x10be1dc50.width   (active)>",
    "<NSLayoutConstraint:0x1c0096b70 H:|-(8)-[_UIButtonBarStackView:0x10be1f620]   (active, names: '|':_UIToolbarContentView:0x10be1e090 )>",
    "<NSLayoutConstraint:0x1c0096bc0 _UIButtonBarStackView:0x10be1f620.trailing == _UIToolbarContentView:0x10be1e090.trailing   (active)>",
    "<NSLayoutConstraint:0x1c409d560 H:|-(8)-[_UIModernBarButton:0x10bd4faa0]   (active, names: '|':_UIButtonBarButton:0x10bd4f650 )>",
    "<NSLayoutConstraint:0x1c409d5b0 H:[_UIModernBarButton:0x10bd4faa0]-(>=8)-|   (active, names: '|':_UIButtonBarButton:0x10bd4f650 )>",
    "<NSLayoutConstraint:0x1c409dba0 H:|-(>=5)-[_UIModernBarButton:0x10bd51920]   (active, names: '|':_UIButtonBarButton:0x10bd512d0 )>",
    "<NSLayoutConstraint:0x1c409dbf0 H:[_UIModernBarButton:0x10bd51920]-(>=5)-|   (active, names: '|':_UIButtonBarButton:0x10bd512d0 )>",
    "<NSLayoutConstraint:0x1c409e690 H:|-(8)-[_UIModernBarButton:0x10bd52b30'Done']   (active, names: '|':_UIButtonBarButton:0x10bd51e40 )>",
    "<NSLayoutConstraint:0x1c409e6e0 H:[_UIModernBarButton:0x10bd52b30'Done']-(8)-|   (active, names: '|':_UIButtonBarButton:0x10bd51e40 )>",
    "<NSLayoutConstraint:0x1c0096ad0 'UISV-canvas-connection' UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'.leading == _UIButtonBarButton:0x10bd4f650.leading   (active)>",
    "<NSLayoutConstraint:0x1c0283930 'UISV-canvas-connection' UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'.trailing == _UIButtonBarButton:0x10bd51e40.trailing   (active)>",
    "<NSLayoutConstraint:0x1c0283980 'UISV-spacing' H:[_UIButtonBarButton:0x10bd4f650]-(0)-[UIView:0x10bd510f0]   (active)>",
    "<NSLayoutConstraint:0x1c02839d0 'UISV-spacing' H:[UIView:0x10bd510f0]-(0)-[_UIButtonBarButton:0x10bd512d0]   (active)>",
    "<NSLayoutConstraint:0x1c0283a20 'UISV-spacing' H:[_UIButtonBarButton:0x10bd512d0]-(0)-[UIView:0x10bd51c60]   (active)>",
    "<NSLayoutConstraint:0x1c0283a70 'UISV-spacing' H:[UIView:0x10bd51c60]-(0)-[_UIButtonBarButton:0x10bd51e40]   (active)>",
    "<NSLayoutConstraint:0x1c0284470 'UIView-Encapsulated-Layout-Width' UIToolbar:0x10be1dc50.width == 0   (active)>",
    "<NSLayoutConstraint:0x1c00969e0 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'](LTR)   (active, names: '|':_UIButtonBarStackView:0x10be1f620 )>",
    "<NSLayoutConstraint:0x1c0096a80 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide']-(0)-|(LTR)   (active, names: '|':_UIButtonBarStackView:0x10be1f620 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x1c409d5b0 H:[_UIModernBarButton:0x10bd4faa0]-(>=8)-|   (active, names: '|':_UIButtonBarButton:0x10bd4f650 )>

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.
2018-07-12 16:42:30.876255+0100 MyApp[3763:346405] [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. 
    (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x1c0284380 h=-&- v=-&- _UIToolbarContentView:0x10be1e090.width == UIToolbar:0x10be1dc50.width   (active)>",
    "<NSLayoutConstraint:0x1c0096b70 H:|-(8)-[_UIButtonBarStackView:0x10be1f620]   (active, names: '|':_UIToolbarContentView:0x10be1e090 )>",
    "<NSLayoutConstraint:0x1c0096bc0 _UIButtonBarStackView:0x10be1f620.trailing == _UIToolbarContentView:0x10be1e090.trailing   (active)>",
    "<NSLayoutConstraint:0x1c409dba0 H:|-(>=5)-[_UIModernBarButton:0x10bd51920]   (active, names: '|':_UIButtonBarButton:0x10bd512d0 )>",
    "<NSLayoutConstraint:0x1c409dbf0 H:[_UIModernBarButton:0x10bd51920]-(>=5)-|   (active, names: '|':_UIButtonBarButton:0x10bd512d0 )>",
    "<NSLayoutConstraint:0x1c409e690 H:|-(8)-[_UIModernBarButton:0x10bd52b30'Done']   (active, names: '|':_UIButtonBarButton:0x10bd51e40 )>",
    "<NSLayoutConstraint:0x1c409e6e0 H:[_UIModernBarButton:0x10bd52b30'Done']-(8)-|   (active, names: '|':_UIButtonBarButton:0x10bd51e40 )>",
    "<NSLayoutConstraint:0x1c0096ad0 'UISV-canvas-connection' UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'.leading == _UIButtonBarButton:0x10bd4f650.leading   (active)>",
    "<NSLayoutConstraint:0x1c0283930 'UISV-canvas-connection' UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'.trailing == _UIButtonBarButton:0x10bd51e40.trailing   (active)>",
    "<NSLayoutConstraint:0x1c0283980 'UISV-spacing' H:[_UIButtonBarButton:0x10bd4f650]-(0)-[UIView:0x10bd510f0]   (active)>",
    "<NSLayoutConstraint:0x1c02839d0 'UISV-spacing' H:[UIView:0x10bd510f0]-(0)-[_UIButtonBarButton:0x10bd512d0]   (active)>",
    "<NSLayoutConstraint:0x1c0283a20 'UISV-spacing' H:[_UIButtonBarButton:0x10bd512d0]-(0)-[UIView:0x10bd51c60]   (active)>",
    "<NSLayoutConstraint:0x1c0283a70 'UISV-spacing' H:[UIView:0x10bd51c60]-(0)-[_UIButtonBarButton:0x10bd51e40]   (active)>",
    "<NSLayoutConstraint:0x1c0284470 'UIView-Encapsulated-Layout-Width' UIToolbar:0x10be1dc50.width == 0   (active)>",
    "<NSLayoutConstraint:0x1c00969e0 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'](LTR)   (active, names: '|':_UIButtonBarStackView:0x10be1f620 )>",
    "<NSLayoutConstraint:0x1c0096a80 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide']-(0)-|(LTR)   (active, names: '|':_UIButtonBarStackView:0x10be1f620 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x1c409dbf0 H:[_UIModernBarButton:0x10bd51920]-(>=5)-|   (active, names: '|':_UIButtonBarButton:0x10bd512d0 )>

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.
2018-07-12 16:42:30.879831+0100 MyApp[3763:346405] [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. 
    (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x1c0284380 h=-&- v=-&- _UIToolbarContentView:0x10be1e090.width == UIToolbar:0x10be1dc50.width   (active)>",
    "<NSLayoutConstraint:0x1c0096b70 H:|-(8)-[_UIButtonBarStackView:0x10be1f620]   (active, names: '|':_UIToolbarContentView:0x10be1e090 )>",
    "<NSLayoutConstraint:0x1c0096bc0 _UIButtonBarStackView:0x10be1f620.trailing == _UIToolbarContentView:0x10be1e090.trailing   (active)>",
    "<NSLayoutConstraint:0x1c409e690 H:|-(8)-[_UIModernBarButton:0x10bd52b30'Done']   (active, names: '|':_UIButtonBarButton:0x10bd51e40 )>",
    "<NSLayoutConstraint:0x1c409e6e0 H:[_UIModernBarButton:0x10bd52b30'Done']-(8)-|   (active, names: '|':_UIButtonBarButton:0x10bd51e40 )>",
    "<NSLayoutConstraint:0x1c0096ad0 'UISV-canvas-connection' UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'.leading == _UIButtonBarButton:0x10bd4f650.leading   (active)>",
    "<NSLayoutConstraint:0x1c0283930 'UISV-canvas-connection' UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'.trailing == _UIButtonBarButton:0x10bd51e40.trailing   (active)>",
    "<NSLayoutConstraint:0x1c0283980 'UISV-spacing' H:[_UIButtonBarButton:0x10bd4f650]-(0)-[UIView:0x10bd510f0]   (active)>",
    "<NSLayoutConstraint:0x1c02839d0 'UISV-spacing' H:[UIView:0x10bd510f0]-(0)-[_UIButtonBarButton:0x10bd512d0]   (active)>",
    "<NSLayoutConstraint:0x1c0283a20 'UISV-spacing' H:[_UIButtonBarButton:0x10bd512d0]-(0)-[UIView:0x10bd51c60]   (active)>",
    "<NSLayoutConstraint:0x1c0283a70 'UISV-spacing' H:[UIView:0x10bd51c60]-(0)-[_UIButtonBarButton:0x10bd51e40]   (active)>",
    "<NSLayoutConstraint:0x1c0284470 'UIView-Encapsulated-Layout-Width' UIToolbar:0x10be1dc50.width == 0   (active)>",
    "<NSLayoutConstraint:0x1c00969e0 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'](LTR)   (active, names: '|':_UIButtonBarStackView:0x10be1f620 )>",
    "<NSLayoutConstraint:0x1c0096a80 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide']-(0)-|(LTR)   (active, names: '|':_UIButtonBarStackView:0x10be1f620 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x1c409e6e0 H:[_UIModernBarButton:0x10bd52b30'Done']-(8)-|   (active, names: '|':_UIButtonBarButton:0x10bd51e40 )>

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.
2018-07-12 16:42:30.881915+0100 MyApp[3763:346405] [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. 
    (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x1c0284380 h=-&- v=-&- _UIToolbarContentView:0x10be1e090.width == UIToolbar:0x10be1dc50.width   (active)>",
    "<NSLayoutConstraint:0x1c0096b70 H:|-(8)-[_UIButtonBarStackView:0x10be1f620]   (active, names: '|':_UIToolbarContentView:0x10be1e090 )>",
    "<NSLayoutConstraint:0x1c0096bc0 _UIButtonBarStackView:0x10be1f620.trailing == _UIToolbarContentView:0x10be1e090.trailing   (active)>",
    "<NSLayoutConstraint:0x1c0096ad0 'UISV-canvas-connection' UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'.leading == _UIButtonBarButton:0x10bd4f650.leading   (active)>",
    "<NSLayoutConstraint:0x1c0283930 'UISV-canvas-connection' UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'.trailing == _UIButtonBarButton:0x10bd51e40.trailing   (active)>",
    "<NSLayoutConstraint:0x1c0283980 'UISV-spacing' H:[_UIButtonBarButton:0x10bd4f650]-(0)-[UIView:0x10bd510f0]   (active)>",
    "<NSLayoutConstraint:0x1c02839d0 'UISV-spacing' H:[UIView:0x10bd510f0]-(0)-[_UIButtonBarButton:0x10bd512d0]   (active)>",
    "<NSLayoutConstraint:0x1c0283a20 'UISV-spacing' H:[_UIButtonBarButton:0x10bd512d0]-(0)-[UIView:0x10bd51c60]   (active)>",
    "<NSLayoutConstraint:0x1c0283a70 'UISV-spacing' H:[UIView:0x10bd51c60]-(0)-[_UIButtonBarButton:0x10bd51e40]   (active)>",
    "<NSLayoutConstraint:0x1c0284470 'UIView-Encapsulated-Layout-Width' UIToolbar:0x10be1dc50.width == 0   (active)>",
    "<NSLayoutConstraint:0x1c00969e0 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide'](LTR)   (active, names: '|':_UIButtonBarStackView:0x10be1f620 )>",
    "<NSLayoutConstraint:0x1c0096a80 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x1c01be5a0'UIViewLayoutMarginsGuide']-(0)-|(LTR)   (active, names: '|':_UIButtonBarStackView:0x10be1f620 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x1c0283a70 'UISV-spacing' H:[UIView:0x10bd51c60]-(0)-[_UIButtonBarButton:0x10bd51e40]   (active)>

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.
2018-07-12 16:42:30.882524+0100 MyApp[3763:346405] [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. 
    (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x1c0284380 h=-&- v=-&- _UIToolbarContentView:0x10be1e090.width == UIToolbar:0x10be1dc50.width   (active)>",
    "<NSLayoutConstraint:0x1c0096b70 H:|-(8)-[_UIButtonBarStackView:0x10be1f620]   (active, names: '|':_UIToolbarContentView:0x10be1e090 )>",
    "<NSLayoutConstraint:0x1c0096bc0 _UIButtonBarStackView:0x10be1f620.trailing == _UIToolbarContentView:0x10be1e090.trailing   (active)>",
    "<NSLayoutConstraint:0x1c0284470 'UIView-Encapsulated-Layout-Width' UIToolbar:0x10be1dc50.width == 0   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x1c0096bc0 _UIButtonBarStackView:0x10be1f620.trailing == _UIToolbarContentView:0x10be1e090.trailing   (active)>

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.

Answer 1

UIButtonBars 用于创建自定义键盘快捷键，并由 UITextInputAssistantItem 管理，当“文本字段”成为 First Responder 时调用它。为了防止冲突的约束消息，您可以初始化 ButtonGroups。当我有许多 textFields 时，我会创建一个 outlet 集合并将每个 textField 添加到集合中。然后在 ViewDidLoad 我运行以下代码:

        for textField in TextFields{
          // Set BarButtonGroups to avoid layout constraint errors
          textField.inputAssistantItem.leadingBarButtonGroups = []
          textField.inputAssistantItem.trailingBarButtonGroups = []
        }