How to create Gradient border with rounded corners at UIView in Swift 4

Question

I want to set border color with the gradient left to right [Red, Green] at UIView. Like example:

I tried below code: -

class View: UIView {

    override func layoutSubviews() {
        super.layoutSubviews()

        let path = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: [.topLeft, .bottomLeft, .topRight, .bottomRight], cornerRadii: CGSize(width: frame.size.height / 2, height: frame.size.height / 2))

        let gradient = CAGradientLayer()
        gradient.frame =  CGRect(origin: CGPoint.zero, size: frame.size)
        gradient.colors = [UIColor.green.cgColor, UIColor.red.cgColor]

        let shape = CAShapeLayer()
        shape.lineWidth = 10
        shape.path = path.cgPath
        shape.strokeColor = UIColor.black.cgColor
        shape.fillColor = UIColor.clear.cgColor
        gradient.mask = shape

        layer.insertSublayer(gradient, at: 0)
    }
}

There is three problem which I am not able to resolve: -
1- I have set lineWidth 10 but its showing width 10 at corners and at horizontal/vertical only 5.
2- I want to show the gradient from left to right not top to bottom.

I tried below code to set gradient from left to right but not working: -

//        gradient.frame =  CGRect(origin: CGPoint.zero, size: frame.size)
        gradient.startPoint = CGPoint(x: 0.0, y: 0.5)
        gradient.endPoint = CGPoint(x: 1.0, y: 0.5)

Please help. Thanks in advance.

Answer 1

Edit

I want to set border from left to right

You need to change gradient.startPoint and gradient.endPoint

enum Direction {
    case horizontal
    case vertical
}

class View: UIView {

init(frame: CGRect, cornerRadius: CGFloat, colors: [UIColor], lineWidth: CGFloat = 5, direction: Direction = .horizontal) {
    super.init(frame: frame)

    self.layer.cornerRadius = cornerRadius
    self.layer.masksToBounds = true
    let gradient = CAGradientLayer()
    gradient.frame = CGRect(origin: CGPoint.zero, size: self.frame.size)
    gradient.colors = colors.map({ (color) -> CGColor in
        color.cgColor
    })

    switch direction {
    case .horizontal:
        gradient.startPoint = CGPoint(x: 0, y: 1)
        gradient.endPoint = CGPoint(x: 1, y: 1)
    case .vertical:
        gradient.startPoint = CGPoint(x: 0, y: 0)
        gradient.endPoint = CGPoint(x: 0, y: 1)
    }

    let shape = CAShapeLayer()
    shape.lineWidth = lineWidth
    shape.path = UIBezierPath(roundedRect: self.bounds.insetBy(dx: lineWidth, 
    dy: lineWidth), cornerRadius: cornerRadius).cgPath
    shape.strokeColor = UIColor.black.cgColor
    shape.fillColor = UIColor.clear.cgColor
    gradient.mask = shape

    self.layer.addSublayer(gradient)
}

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

As you can see, I added some extra parameters. I solved this issue by adding inset to the roundedRect:

shape.path = UIBezierPath(roundedRect: self.bounds.insetBy(dx: lineWidth, 
dy: lineWidth), cornerRadius: cornerRadius).cgPath

How to use it:

let myView = View(frame: CGRect(x: 0, y: 0, width: 200, height: 50), cornerRadius: 25, colors: [UIColor.red, .orange, .yellow], lineWidth: 2, direction: .horizontal)
    myView.center = view.center
    view.addSubview(myView)

Screenshot:

roundedViewWithGradient