ios 11 - UIBarButtonItem 内的 UIButton 导致自动布局错误

我在将 UIButton 添加到 UIBarButtonItem 时遇到了一个已知问题。我尝试按照建议添加自动布局约束堆栈溢出 https://stackoverflow.com/a/46336639/505603但我收到如下所述的错误。

UIButton *sortButton = [UIButton buttonWithType:UIButtonTypeCustom];
[sortButton setFrame:CGRectMake(10, 0, 100, 30)];
[sortButton setTitle:@"Sort" forState:UIControlStateNormal];
[[sortButton titleLabel] setFont:[UIFont boldSystemFontOfSize:13]];
[sortButton setBackgroundImage:[UIImage imageNamed:@"backgroun-button.png"] forState:UIControlStateNormal];
[sortButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
[sortButton addTarget:self action:@selector(sortCollection:) forControlEvents:UIControlEventTouchUpInside];
[sortButton applyNavBarConstraints:100 height:30];

[self setSortCollection:item];

[self setToolbarItems:[NSArray arrayWithObjects:self.sortCollection, nil]];

自动布局约束：

- (void)applyNavBarConstraints:(CGFloat)width height:(CGFloat)height
{
    if (width == 0 || height == 0) {
        return;
    }

    NSLayoutConstraint* w = [self.widthAnchor constraintEqualToConstant:width];
    NSLayoutConstraint * h = [self.heightAnchor constraintEqualToConstant:height];

    [w setActive:YES];
    [h setActive:YES];
}

堆栈跟踪：

[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:0x608000280af0 h=--& v=--& UIToolbar:0x7f85ca1327e0.width == 768   (active)>",
    "<NSLayoutConstraint:0x6000002826c0 _UIToolbarContentView:0x7f85ca1307b0.trailing == UIToolbar:0x7f85ca1327e0.trailing   (active)>",
    "<NSLayoutConstraint:0x600000282580 H:|-(0)-[_UIToolbarContentView:0x7f85ca1307b0]   (active, names: '|':UIToolbar:0x7f85ca1327e0 )>",
    "<NSLayoutConstraint:0x600000285410 H:|-(0)-[_UIButtonBarStackView:0x7f85ca135660]   (active, names: '|':_UIToolbarContentView:0x7f85ca1307b0 )>",
    "<NSLayoutConstraint:0x600000285460 _UIButtonBarStackView:0x7f85ca135660.trailing == _UIToolbarContentView:0x7f85ca1307b0.trailing   (active)>",
    "<NSLayoutConstraint:0x600000285500 UIButton:0x7f85ca131b90'Sortieren'.width == 100   (active)>",
    "<NSLayoutConstraint:0x608000280ff0 'UISV-canvas-connection' UILayoutGuide:0x6000001ba240'UIViewLayoutMarginsGuide'.leading == UIButton:0x7f85ca131b90'Sortieren'.leading   (active)>",
    "<NSLayoutConstraint:0x608000280d70 'UISV-canvas-connection' UILayoutGuide:0x6000001ba240'UIViewLayoutMarginsGuide'.trailing == UIButton:0x7f85ca131b90'Sortieren'.trailing   (active)>",
    "<NSLayoutConstraint:0x600000284f10 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x6000001ba240'UIViewLayoutMarginsGuide'](LTR)   (active, names: '|':_UIButtonBarStackView:0x7f85ca135660 )>",
    "<NSLayoutConstraint:0x600000285190 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x6000001ba240'UIViewLayoutMarginsGuide']-(0)-|(LTR)   (active, names: '|':_UIButtonBarStackView:0x7f85ca135660 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x600000285500 UIButton:0x7f85ca131b90'Sortieren'.width == 100   (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.

栏按钮被限制在左侧和右侧，因此必须打破宽度限制。您可以通过向工具栏添加灵活空间来解决此问题。这允许您限制按钮的宽度并让灵活的空间填充其余部分。

Obj C:

UIBarButtonItem *flexItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:self action:nil];
[self setToolbarItems:[NSArray arrayWithObjects:self.sortCollection, flexItem, nil]];

Swift:

let flexItem = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
toolbar.setItems([barButtonItem, flexItem], animated: false)