如何以编程方式对按钮施加约束（水平间距）

Question

我想并排放置两个按钮。

一个（ testButton ）当前位于正确的位置- 垂直和水平对齐 -使用Interface Builder自动布局。

我们看看吧 ：

我想以编程方式并排放置另一个（ okButton ）：

我想要的预览：

我添加了一个CenterY约束和一个Leading / Trailing约束，但是它不起作用，测试按钮的UIButton宽度会增加。

让我们看一下Debug View Hierarchy ：

和我的代码：

override func viewDidLoad() {
        super.viewDidLoad()

        let constraintAlignY = NSLayoutConstraint(
            item: okButton,
            attribute: .CenterY,
            relatedBy: .Equal,
            toItem: testButton,
            attribute: .CenterY,
            multiplier: 1,
            constant: 0)

        let constraintXSpace = NSLayoutConstraint(
            item: okButton,
            attribute: .Leading,
            relatedBy: .Equal,
            toItem: testButton,
            attribute: .Trailing,
            multiplier: 1,
            constant: 8)

        view.addConstraint(constraintAlignY)
        view.addConstraint(constraintXSpace)
    }

警告控制台：

2015-05-09 23:03:10.439 MainThreading[10227:663061] 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) 
(
    "<NSLayoutConstraint:0x7b8c8ee0 UIButton:0x7b8cde90'test'.centerY == UIView:0x7b8ced40.centerY>",
    "<NSIBPrototypingLayoutConstraint:0x7b8c40f0 'IB auto generated at build time for view with fixed frame' V:|-(191)-[UIButton:0x7b8ce8d0'ok']   (Names: '|':UIView:0x7b8ced40 )>",
    "<NSIBPrototypingLayoutConstraint:0x7b8c77f0 'IB auto generated at build time for view with fixed frame' V:[UIButton:0x7b8ce8d0'ok'(30)]>",
    "<NSLayoutConstraint:0x7b8c4f50 UIButton:0x7b8ce8d0'ok'.centerY == UIButton:0x7b8cde90'test'.centerY>",
    "<NSLayoutConstraint:0x7b8da380 'UIView-Encapsulated-Layout-Height' V:[UIView:0x7b8ced40(480)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7b8c4f50 UIButton:0x7b8ce8d0'ok'.centerY == UIButton:0x7b8cde90'test'.centerY>

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.
(lldb) 

任何想法 ？ 谢谢 ！

Answer 1

如果您添加视图并且自己不添加任何约束，则系统会为您添加约束（在顶部和左侧），所以我认为这就是问题所在。

这些系统添加的约束与您在代码中添加的约束冲突。 由于您的最终目标是动态添加视图，因此应在代码中而不是IB中添加“确定”按钮。 对于任何添加了代码的视图，请确保将translatesAutoresizingMaskIntoConstraints设置为false 。

如果您确实需要在IB中添加该按钮，则可以通过选择“ 在构建时删除 ”复选框来为其赋予约束，但可以将其删除。 然后，在代码中添加新代码将是安全的。