Stroke masked CALayer in iOS

Question

I\'m trying to create a label (or any other view for that matter) with one rounded corner and a stroke/border. I can achieve the former using the following code:

Answer 1

If you subclass CALayer, you could instantiate it with the mask you want, and also override layoutSubLayers to include the border you want on that mask.

Could do this a couple ways. Below Ill do it by using the path of the given mask, and assigning that to class property to be used for constructing the new border in layoutSubLayers. There is potential that this method could be called multiple times, so I also set a boolean to track this. (Could also assign the border as a class property, and remove/re-add each time. For now, I use bool check.

Swift 3:

class CustomLayer: CALayer {

    private var path: CGPath?
    private var borderSet: Bool = false

    init(maskLayer: CAShapeLayer) {
        super.init()
        self.path = maskLayer.path
        self.frame = maskLayer.frame
        self.bounds = maskLayer.bounds
        self.mask = maskLayer
    }

    override func layoutSublayers() {

        let newBorder = CAShapeLayer()

        newBorder.lineWidth = 12
        newBorder.path = self.path
        newBorder.strokeColor = UIColor.black.cgColor
        newBorder.fillColor = nil


        if(!borderSet) {
            self.addSublayer(newBorder)
            self.borderSet = true
        }

    }

    required override init(layer: Any) {
        super.init(layer: layer)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}