Swift - How to create a view with a shape cropped in it - swift

Question

I'm trying to achieve the result shown in the image using swift 1.2 and xcode 6.
Basically I want to create a view with a shape cut in it to be able to see the the view below to make a tutorial for my app.
I know how to create a circular shape but i don't know how to cut it out in a view.
I need a complete example on how to do it please.
Thanks in advance

Answer 1

Even though there is an answer, i'd like to share my way:
// 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 2

//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 3

Here is sample code for how you can make a circle Mask for a UIView:
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
Here is what I made in the playground:

Answer 4

The easiest way to do this would be to create a png image with partly transparent white around the outside and a clear circle in the middle. Then stack 2 image views on top of each other, with the masking image on top, and set its "opaque" flag to false.
You could also do this by creating a CAShapeLayer and set it up to use a translucent white color, then install a shape that is the square with the hole cut out of it shape. You'd install that shape layer on top of your image view's layer.
The most general-purpose way to do that would be to create a custom subclass of UIImageView and have the init method of your subclass create and install the shape layer. I just created a gist yesterday that illustrated creating a custom subclass of UIImageView. Here is the link: ImageViewWithGradient gist
That gist creates a gradient layer. It would be a simple matter to adapt it to create a shape layer instead, and if you modified the layoutSubviews method you could make it adapt the view and path if the image view gets resized.
EDIT:
Ok, I took the extra step of creating a playground that creates a cropping image view. You can find that at ImageViewWithMask on github
The resulting image for my playground looks like this:

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)
}
}