带有 UIBarButtonItem LayoutConstraint 问题的 UIToolbar

Question

我正在以编程方式创建一个带有 UIBarButtonItem 的 UIToolbar。 我没有为此 ViewController 使用 .xib 或 storyboard。 这是我如何创建它的代码。

NSMutableArray *items = [[NSMutableArray alloc] init];

UIBarButtonItem *buttonItem;
buttonItem = [[UIBarButtonItem alloc ] initWithTitle: [Language get:@"Home" alter:nil]
                                               style: UIBarButtonItemStyleBordered
                                              target: self
                                              action: @selector(viewChangeTo)];
[items addObject:buttonItem];

toolbar = [[UIToolbar alloc] init];
toolbar.frame = CGRectMake(0, 0, 1024, 44);
[toolbar setItems:items animated:NO];
[self.view addSubview:toolbar];

每次加载视图时，我都会收到 LayoutConstraints 错误。

[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:0x6000023de350 H:|-(20)-[_UIModernBarButton:0x7fed8c463e00'Home']   (active, names: '|':_UIButtonBarButton:0x7fed8c463bb0 )>",
"<NSLayoutConstraint:0x6000023de3a0 H:[_UIModernBarButton:0x7fed8c463e00'Home']-(20)-|   (active, names: '|':_UIButtonBarButton:0x7fed8c463bb0 )>",
"<NSLayoutConstraint:0x6000023dff70 '_UITemporaryLayoutWidth' _UIButtonBarButton:0x7fed8c463bb0.width == 0   (active)>

Will attempt to recover by breaking constraint 

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.
2019-01-21 13:14:24.777354+0800 M[50994:10130357] [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:0x6000023de530 _UIModernBarButton:0x7fed8c463e00'Home'.lastBaseline == UILayoutGuide:0x6000039eef40'UIViewLayoutMarginsGuide'.bottom   (active)>",
    "<NSLayoutConstraint:0x6000023de580 V:|-(>=0)-[_UIModernBarButton:0x7fed8c463e00'Home']   (active, names: '|':_UIButtonBarButton:0x7fed8c463bb0 )>",
    "<NSLayoutConstraint:0x6000023e5680 UIButtonLabel:0x7fed8c457e90'Home'.centerY == _UIModernBarButton:0x7fed8c463e00'Home'.centerY + 1.5   (active)>",
    "<NSLayoutConstraint:0x6000023e4c80 '_UITemporaryLayoutHeight' _UIButtonBarButton:0x7fed8c463bb0.height == 0   (active)>",
    "<NSLayoutConstraint:0x6000023de490 'UIView-bottomMargin-guide-constraint' V:[UILayoutGuide:0x6000039eef40'UIViewLayoutMarginsGuide']-(16)-|   (active, names: '|':_UIButtonBarButton:0x7fed8c463bb0 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x6000023e5680 UIButtonLabel:0x7fed8c457e90'Home'.centerY == _UIModernBarButton:0x7fed8c463e00'Home'.centerY + 1.5   (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.

Answer 1

使用swift代替： let toolbar = UIToolbar()

使用： let toolBar = UIToolbar(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: 35))

Answer 2

除非您设置 UIToolbar 的框架，否则使用toolbar.sizeToFit()不会捕获 layoutConstraintsIssue。

这个问题发生在我身上，我通过设置工具栏的框架解决了。