Swift - 如何创建一个在其中裁剪的形状的视图

Question

我正在尝试使用swift 1.2和xcode 6来实现图像中显示的结果。

基本上我想创建一个切入形状的视图，以便能够看到下面的视图，为我的应用程序制作教程。我知道如何创建一个圆形，但我不知道如何在视图中剪切它。我需要一个完整的例子来说明如何做到这一点。提前致谢

Answer 1

最简单的方法是创建一个png图像，在外面有一个部分透明的白色，在中间有一个清晰的圆圈。然后将2个图像视图堆叠在一起，将遮罩图像放在顶部，并将其“不透明”标记设置为false。

您也可以通过创建CAShapeLayer并将其设置为使用半透明的白色来完成此操作，然后安装一个形状为正方形的形状，并将其切出形状。您可以在图像视图的图层上安装该形状图层。

最常用的方法是创建UIImageView的自定义子类，并使子类的init方法创建并安装形状图层。我昨天创建了一个要点，说明了创建UIImageView的自定义子类。这是链接：ImageViewWithGradient gist

该要点创建了一个渐变层。改编它以创建形状图层将是一件简单的事情，如果您修改了layoutSubviews方法，则可以在调整图像视图大小时使其适应视图和路径。

编辑：

好的，我采取了额外的步骤来创建一个创建裁剪图像视图的游乐场。你可以在ImageViewWithMask on github找到它

我的游乐场生成的图像如下所示：

Answer 2

即使有答案，我想分享我的方式：

// Let's say that you have an outlet to the image view called imageView
// Create the white view 
let whiteView = UIView(frame: imageView.bounds) 
let maskLayer = CAShapeLayer() //create the mask layer

// Set the radius to 1/3 of the screen width
let radius : CGFloat = imageView.bounds.width/3 

// Create a path with the rectangle in it.
let path = UIBezierPath(rect: imageView.bounds)
// Put a circle path in the middle
path.addArcWithCenter(imageView.center, radius: radius, startAngle: 0.0, endAngle: CGFloat(2*M_PI), clockwise: true)

// Give the mask layer the path you just draw
maskLayer.path = path.CGPath
// Fill rule set to exclude intersected paths
maskLayer.fillRule = kCAFillRuleEvenOdd

// By now the mask is a rectangle with a circle cut out of it. Set the mask to the view and clip.
whiteView.layer.mask = maskLayer
whiteView.clipsToBounds = true

whiteView.alpha = 0.8
whiteView.backgroundColor = UIColor.whiteColor()

//If you are in a VC add to the VC's view (over the image)
view.addSubview(whiteView)    
// Annnnnd you're done.

Answer 3

以下是如何为UIView制作圆形蒙版的示例代码：

let sampleView = UIView(frame: UIScreen.mainScreen().bounds)
let maskLayer = CALayer()
maskLayer.frame = sampleView.bounds
let circleLayer = CAShapeLayer()
//assume the circle's radius is 100
circleLayer.frame = CGRectMake(sampleView.center.x - 100, sampleView.center.y - 100, 200, 200)
let circlePath = UIBezierPath(ovalInRect: CGRectMake(0, 0, 200, 200))
circleLayer.path = circlePath.CGPath
circleLayer.fillColor = UIColor.blackColor().CGColor
maskLayer.addSublayer(circleLayer)

sampleView.layer.mask = maskLayer

这是我在操场上制作的：

Answer 4

    //assume you create a UIImageView and content image before execute this code
  let sampleMask = UIView()
    sampleMask.frame = self.view.frame
    sampleMask.backgroundColor =  UIColor.black.withAlphaComponent(0.6)
    //assume you work in UIViewcontroller
    self.view.addSubview(sampleMask)
    let maskLayer = CALayer()
    maskLayer.frame = sampleMask.bounds
    let circleLayer = CAShapeLayer()
    //assume the circle's radius is 150
    circleLayer.frame = CGRect(x:0 , y:0,width: sampleMask.frame.size.width,height: sampleMask.frame.size.height)
    let finalPath = UIBezierPath(roundedRect: CGRect(x:0 , y:0,width: sampleMask.frame.size.width,height: sampleMask.frame.size.height), cornerRadius: 0)
    let circlePath = UIBezierPath(ovalIn: CGRect(x:sampleMask.center.x - 150, y:sampleMask.center.y - 150, width: 300, height: 300))
    finalPath.append(circlePath.reversing())
    circleLayer.path = finalPath.cgPath
    circleLayer.borderColor = UIColor.white.withAlphaComponent(1).cgColor
     circleLayer.borderWidth = 1
    maskLayer.addSublayer(circleLayer)

    sampleMask.layer.mask = maskLayer

Answer 5

class MakeTransparentHoleOnOverlayView: UIView {

    @IBOutlet weak var transparentHoleView: UIView!

    // MARK: - Drawing

    override func draw(_ rect: CGRect) {
        super.draw(rect)

        if self.transparentHoleView != nil {
            // Ensures to use the current background color to set the filling color
            self.backgroundColor?.setFill()
            UIRectFill(rect)

            let layer = CAShapeLayer()
            let path = CGMutablePath()

            // Make hole in view's overlay
            // NOTE: Here, instead of using the transparentHoleView UIView we could use a specific CFRect location instead...
            path.addRect(transparentHoleView.frame)
            path.addRect(bounds)

            layer.path = path
            layer.fillRule = kCAFillRuleEvenOdd
            self.layer.mask = layer
        }
    }

    override func layoutSubviews () {
        super.layoutSubviews()
    }

    // MARK: - Initialization

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
    }
}