xcode 在 Swift 上的另一个 UIView 中使用 UIView 作为掩码

Using an UIView as a Mask in another UIView on Swift

提问by DevRenanGaspar

I am developing an App on xCode with Swift. My screen has an Image of an animal (outlet "backImage"), over this image I have a view (outlet "coverView"), color black, which covers all the screen. So so far you can't see the animal image, because the "coverView" is in front of it. Then I have another view (outlet "maskView") which is smaller and it's over the big view "coverView". What I want is to use this "maskView" as mask and therefor see the "backImage" through it, like a window.

我正在使用 Swift 在 xCode 上开发应用程序。我的屏幕有一个动物的图像（出口“backImage”），在这个图像上我有一个视图（出口“coverView”），颜色为黑色，它覆盖了整个屏幕。到目前为止你还看不到动物图像，因为“coverView”在它的前面。然后我有另一个较小的视图（出口“maskView”），它位于大视图“coverView”上方。我想要的是使用这个“maskView”作为掩码，因此通过它看到“backImage”，就像一个窗口。

Is there anyone out there able to figure this out?

有没有人能够弄清楚这一点？

Here is my screen, I want to see the woman character behind the big gray view through the smaller white view:

这是我的屏幕，我想通过较小的白色视图看到大灰色视图后面的女性角色：

回答by Alexandre Lara

You can set the alphaproperty from your mask view and add in front of the other view, for instance:

您可以alpha从掩码视图设置属性并添加到另一个视图的前面，例如：

let maskView = UIView()
maskView.backgroundColor = UIColor(white: 0, alpha: 0.5) //you can modify this to whatever you need
maskView.frame = CGRect(x: 0, y: 0, width: imageView.frame.width, height: imageView.frame.height)

yourView.addSubview(maskView)

---

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EDIT: Now that you edited your question with an image, now I see what you need, so here is how you can accomplish that.

编辑：既然你用图像编辑了你的问题，现在我知道你需要什么，所以这里是你如何完成它。

func setMask(with hole: CGRect, in view: UIView){

    // Create a mutable path and add a rectangle that will be h
    let mutablePath = CGMutablePath()
    mutablePath.addRect(view.bounds)
    mutablePath.addRect(hole)

    // Create a shape layer and cut out the intersection
    let mask = CAShapeLayer()
    mask.path = mutablePath
    mask.fillRule = kCAFillRuleEvenOdd

    // Add the mask to the view
    view.layer.mask = mask

}

With this function, all you need is to have a view and create a shape that it's going to be a hole in that view, for instance:

使用此功能，您只需要拥有一个视图并创建一个形状，该形状将成为该视图中的一个洞，例如：

// Create the view (you can also use a view created in the storyboard)
let newView = UIView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height))
newView.backgroundColor = UIColor(white: 0, alpha: 1)

// You can play with these values and find one that fills your need
let rectangularHole = CGRect(x: view.bounds.width*0.3, y: view.bounds.height*0.3, width: view.bounds.width*0.5, height: view.bounds.height*0.5)

// Set the mask in the created view        
setMask(with: rectangularHole, in: newView)

回答by DevRenanGaspar

Thank you, @Alexandre Lara! You did it!

谢谢你，@Alexandre Lara！你做到了！

Here goes the solution:

解决方法如下：

@IBOutlet weak var windowView: UIView!
@IBOutlet weak var bigCoverView: UIView!

func setMask(with hole: CGRect, in view: UIView){

    // Create a mutable path and add a rectangle that will be h
    let mutablePath = CGMutablePath()
    mutablePath.addRect(view.bounds)
    mutablePath.addRect(hole)

    // Create a shape layer and cut out the intersection
    let mask = CAShapeLayer()
    mask.path = mutablePath
    mask.fillRule = kCAFillRuleEvenOdd

    // Add the mask to the view
    view.layer.mask = mask

}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    let rectangularHole = windowView.frame.integral

    // Set the mask in the created view
    setMask(with: rectangularHole, in: bigCoverView!)

}