xcode 如何在 addSubview 之后添加约束，以便子视图随父视图调整大小

How to add constraints after an addSubview so the subview resizes with the superview

提问by ericg

I have a sample project which demonstrates the problem here

我有一个示例项目，它演示了这里的问题

https://github.com/ericgorr/autolayout_with_addsubview.git

https://github.com/ericgorr/autolayout_with_addsubview.git

I have a view called CalcView which I want to programmatically add as a subview to a view on the main window for the app. When I resize my window, I want CalcView to be resized.

我有一个名为 CalcView 的视图，我想以编程方式将其作为子视图添加到应用程序主窗口上的视图中。当我调整窗口大小时，我希望调整 CalcView 的大小。

In windowDidLoad in MainWindowController, I add the subview by doing:

在 MainWindowController 的 windowDidLoad 中，我通过执行以下操作添加子视图：

let calcViewController  = ELIZCalcView()
let calcView            = calcViewController.view

calcContentView?.addSubview( calcViewController.view )

I try to add the constraints by doing:

我尝试通过执行以下操作来添加约束：

let bindings            = [ "calcView": calcView ]

let horizontalContraint:[AnyObject] = NSLayoutConstraint.constraintsWithVisualFormat( "H:|[calcView]|", options: NSLayoutFormatOptions(0), metrics: nil, views: bindings )
let verticalContraint:[AnyObject]   = NSLayoutConstraint.constraintsWithVisualFormat( "V:|[calcView]|", options: NSLayoutFormatOptions(0), metrics: nil, views: bindings )

calcContentView?.addConstraints( horizontalContraint )
calcContentView?.addConstraints( verticalContraint )

Now, for someone who knows how to properly interpret that code, it is likely very apparent that it will not work. After I run my app, I cannot resize the window at all. Additionally, I see the following error message in the console:

现在，对于知道如何正确解释该代码的人来说，很明显它是行不通的。运行我的应用程序后，我根本无法调整窗口大小。此外，我在控制台中看到以下错误消息：

2015-07-04 16:04:45.019 aocsCalc[5797:3526462] Unable to simultaneously satisfy constraints: (
    "<NSLayoutConstraint:0x618000082440 V:|-(0)-[NSView:0x600000120f00]   (Names: '|':aocsCalc.ELIZHighlightView:0x608000120500 )>",
    "<NSAutoresizingMaskLayoutConstraint:0x618000084100 h=--& v=&-- V:|-(-2)-[NSView:0x600000120f00]   (Names: '|':aocsCalc.ELIZHighlightView:0x608000120500 )>" )

Will attempt to recover by breaking constraint  <NSLayoutConstraint:0x618000082440 V:|-(0)-[NSView:0x600000120f00]   (Names: '|':aocsCalc.ELIZHighlightView:0x608000120500 )>

Set the NSUserDefault NSConstraintBasedLayoutVisualizeMutuallyExclusiveConstraints to YES to have -[NSWindow visualizeConstraints:] automatically called when this happens.  And/or, break on objc_exception_throw to catch this in the debugger.

If I remove the vertical constraint, the error message goes away and I can resize the window vertically.

如果我删除垂直约束，错误消息就会消失，我可以垂直调整窗口大小。

So, what simple thing do I need to do so CalcView is resized along with the window?

那么，我需要做些什么简单的事情来使 CalcView 与窗口一起调整大小？

回答by NKorotkov

Before you add your calcView as subview try inserting this line of code:

在将 calcView 添加为子视图之前，请尝试插入以下代码行：

calcView.translatesAutoresizingMaskIntoConstraints = false

This should solve your problem.

这应该可以解决您的问题。

By default on UIView/NSView this property is set to YES/true and it creates it's own set of constraints based on autoresizing mask. These auto-made constraints conflict with the ones you've created in code.

默认情况下，在 UIView/NSView 上，此属性设置为 YES/true，它会根据自动调整大小掩码创建自己的一组约束。这些自动生成的约束与您在代码中创建的约束冲突。

It clearly says so in the error description too. On lines 2 and 3 it shows you that there's 2 set of vertical constraints regarding one view - NSView:0x600000120f00, which appears to be your calcView.

它在错误描述中也清楚地说明了这一点。在第 2 行和第 3 行，它向您显示关于一个视图 - 有 2 组垂直约束NSView:0x600000120f00，这似乎是您的 calcView。

<NSLayoutConstraint:0x618000082440 V:|-(0)-[NSView:0x600000120f00] 
<NSAutoresizingMaskLayoutConstraint:0x618000084100 h=--& v=&-- V:|-(-2)-[NSView:0x600000120f00]

They are both vertical. First one wants to snap view to the superview's top with no margin. The second one (created automatically) wants to snap it with a small margin, presumably taken from how it is layed out in Interface Builder.

它们都是垂直的。第一个想要在没有边距的情况下将视图捕捉到超级视图的顶部。第二个（自动创建的）想要用很小的边距来捕捉它，大概是从它在 Interface Builder 中的布局方式获取的。

UPDATE

更新

Create a new Cocoa Application project and paste the following code:

创建一个新的 Cocoa Application 项目并粘贴以下代码：

override func viewDidLoad() {
    super.viewDidLoad()

    let view = NSView()
    view.translatesAutoresizingMaskIntoConstraints = false
    self.view.addSubview(view)

    //Making it red just to see a little better. Ignore this two lines.
    view.wantsLayer = true
    view.layer?.backgroundColor = CGColorCreateGenericRGB(1, 0, 0, 1)
    //-----------------------------------------------------------------

    let views = ["view" : view]
    self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("|-[view]-|", options: NSLayoutFormatOptions(0), metrics: nil, views: views))
    self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-[view]-|", options: nil, metrics: nil, views: views))

}

Newly created NSView is snapped to the View Controllers main view with standard margins (8 points, it's described as "-" in the visual format string) and is resizing with the main view (see pictures). A little tip - you don't have to specify the "H:" in the visual format, only "V:". It's horizontal by default.

新创建的 NSView 以标准边距（8 分，在视觉格式字符串中被描述为“-”）捕捉到视图控制器主视图，并随着主视图调整大小（参见图片）。小提示 - 您不必在视觉格式中指定“H:”，只需指定“V:”。默认情况下它是水平的。

This should give you a good idea of how adding constraints programmatically works. Code might not be optimal, I code in Obj-C and know very little Swift.

这应该让您很好地了解如何以编程方式添加约束。代码可能不是最优的，我用 Obj-C 编写代码并且对 Swift 知之甚少。

I've downloaded your project. Error probably lies somewhere in your complicated view hierarchy and xib manipulation. But that's a whole other story. Also be careful with scroll views, they are a bit tricky when it comes to autolayout, you can find a lot of coverage on that on SO. Happy coding :)

我已经下载了你的项目。错误可能存在于您复杂的视图层次结构和 xib 操作中。但那是另外一回事了。还要小心滚动视图，它们在自动布局方面有点棘手，你可以在 SO 上找到很多关于它的报道。快乐编码:)