存在 UIToolbarContentView 时无法同时满足约束

Posted 2023-02-23

【中文标题】存在 UIToolbarContentView 时无法同时满足约束

【英文标题】：Unable to simultaneously satisfy constraints when UIToolbarContentView is present

【发布时间】：2019-10-23 20:16:36

【问题描述】：

我在日期选择器视图顶部有一个自定义按钮。当日期选择器处于活动状态时，我得到“无法同时满足约束”。在我更新到 Xcode 11 后，错误已经弹出，

这是我的代码：

let toolbar = UIToolbar()
let flexBarButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.flexibleSpace, target: nil, action: nil)
let done = UIBarButtonItem(barButtonSystemItem: .done, target: nil, action: #selector(viewTapped))
toolbar.sizeToFit()
toolbar.setItems([flexBarButton,done], animated: false)
dateInputTextField.inputAccessoryView = toolbar

这是错误：

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:0x7f85a6fe4230 h=--& v=--& _UIToolbarContentView:0x7f85a6d1b8a0.width == 0   (active)>",
    "<NSLayoutConstraint:0x7f85a6c2c220 H:|-(0)-[_UIButtonBarStackView:0x7f85a6d1c0c0]   (active, names: '|':_UIToolbarContentView:0x7f85a6d1b8a0 )>",
    "<NSLayoutConstraint:0x7f85a6c2e5e0 _UIButtonBarStackView:0x7f85a6d1c0c0.trailing == _UIToolbarContentView:0x7f85a6d1b8a0.trailing   (active)>",
    "<NSLayoutConstraint:0x7f85a6c2f920 'TB_Leading_Leading' H:|-(16)-[_UIModernBarButton:0x7f85a6edf790'Done']   (active, names: '|':_UIButtonBarButton:0x7f85a6ed7060 )>",
    "<NSLayoutConstraint:0x7f85a6c2d690 'TB_Trailing_Trailing' H:[_UIModernBarButton:0x7f85a6edf790'Done']-(16)-|   (active, names: '|':_UIButtonBarButton:0x7f85a6ed7060 )>",
    "<NSLayoutConstraint:0x7f85a6f11060 'UISV-canvas-connection' UILayoutGuide:0x7f85a6c22b40'UIViewLayoutMarginsGuide'.leading == UIView:0x7f85a6ed6cd0.leading   (active)>",
    "<NSLayoutConstraint:0x7f85a6f25390 'UISV-canvas-connection' UILayoutGuide:0x7f85a6c22b40'UIViewLayoutMarginsGuide'.trailing == _UIButtonBarButton:0x7f85a6ed7060.trailing   (active)>",
    "<NSLayoutConstraint:0x7f85a6f256e0 'UISV-spacing' H:[UIView:0x7f85a6ed6cd0]-(0)-[_UIButtonBarButton:0x7f85a6ed7060]   (active)>",
    "<NSLayoutConstraint:0x7f85a6c24880 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x7f85a6c22b40'UIViewLayoutMarginsGuide'](LTR)   (active, names: '|':_UIButtonBarStackView:0x7f85a6d1c0c0 )>",
    "<NSLayoutConstraint:0x7f85a6c2c9c0 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x7f85a6c22b40'UIViewLayoutMarginsGuide']-(0)-|(LTR)   (active, names: '|':_UIButtonBarStackView:0x7f85a6d1c0c0 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7f85a6c2d690 'TB_Trailing_Trailing' H:[_UIModernBarButton:0x7f85a6edf790'Done']-(16)-|   (active, names: '|':_UIButtonBarButton:0x7f85a6ed7060 )>

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.

有什么办法可以解决这个错误吗？

【问题讨论】：

我在 UIToolBar 上也看到了这一点。它似乎是指 UIToolBar 在第一个按钮上设置的内部约束，并且它似乎正确显示，所以我现在忽略日志警告。

【参考方案1】：

在我的例子中，这是通过在实例化 UIToolbar 时指定一个有效的框架来解决的。UIToolbar(frame: ..) 而不仅仅是UIToolbar()

例如：

UIToolbar(frame: CGRect(origin: CGPoint.zero, size: CGSize(width: _viewSizeWidth, height: CGFloat(44))))

其中 _viewSizeWidth 是根据窗口大小在别处计算得出的。

【讨论】：

我无法让它工作。你设置了什么尺寸？

谢谢@jk7。在对主视图进行一些调整后，我使用了UIToolbar(frame: CGRect(origin: CGPoint.zero, size: CGSize(width: self.view.bounds.width, height: CGFloat(44))))，对于自定义表格视图单元格中的文本字段，我使用了UIToolbar(frame: CGRect(origin: CGPoint.zero, size: CGSize(width: UIScreen.main.bounds.width, height: CGFloat(44))))。

简单地使用 100 和 100 也可以（来自forums.developer.apple.com/thread/121474#384249）

这也解决了我的冲突约束。这是 Xamarin 版本的代码： var dismissKeyboard = new UIToolbar (new CGRect (0.0f, 0.0f, this.vwPickerContainer.Frame.Width, 50.0f));

【参考方案2】：

Swift 5.2

UIToolbar的宽度设置为屏幕宽度时似乎出现约束错误。高度似乎无关紧要。

我通过设置足够宽以接受UIBarButtonItem(s) 来消除警告。将宽度设置得太小也会引发错误。

let toolBar = UIToolbar(frame: CGRect(origin: .zero, size: CGSize(width: 100, height: 44.0)))

【讨论】：

可以确认，也帮我修好了。