Use radial gradient as an extention for UIView - ios

Question

My goal is to make radial gradient extension for UIView. Here is my code:
extension UIView {
func drawRadialGradient() {
let colors = Colors.gradientColors as CFArray
let gradient = CGGradient(colorsSpace: nil, colors: colors, locations: nil)
guard let gradientValue = gradient else{ return }
let endRadius: CGFloat? = max(frame.width, frame.height) / 2
guard let endRadiusValue = endRadius else{ return }
let bottomcenterCoordinates = CGPoint(x: frame.width / 2, y: frame.height)
let getCurrentContext = UIGraphicsGetCurrentContext()
guard let currentContext = getCurrentContext else{ return }
currentContext.drawRadialGradient(gradientValue, startCenter: bottomcenterCoordinates, startRadius: 0.0, endCenter: bottomcenterCoordinates, endRadius: endRadiusValue, options: CGGradientDrawingOptions.drawsAfterEndLocation)
let radialGradientLayer = CALayer(layer: currentContext)
radialGradientLayer.frame = bounds
radialGradientLayer.masksToBounds = true
self.layer.insertSublayer(radialGradientLayer, at: 1)
}
}
When I call this function in viewDidLoad() or viewWillAppear() the compiler contains no mistakes and no warnings, the function just does not work out. i call it as following:
override func viewDidLoad() {
super.viewDidLoad()
view.drawRadialGradient()
}
For example, I have created an extension function for drawing a Linear Gradient on the UIView and it works, I call it the same way as radial gradient function:
func drawLinearGradient() {
let gradientLayer = CAGradientLayer()
gradientLayer.frame = self.frame
gradientLayer.colors = Colors.gradientColors
gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.95)
gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.05)
self.layer.insertSublayer(gradientLayer, at: 0)
}
For colors I have created a structure:
struct Colors {
static let firstColor = colorPicker(red: 70, green: 183, blue: 0)
static let secondColor = colorPicker(red: 0, green: 170, blue: 116)
static let thirdColor = colorPicker(red: 20, green: 0, blue: 204)
static let gradientColors = [firstColor.cgColor, secondColor.cgColor, thirdColor.cgColor]
static func colorPicker(red: CGFloat, green: CGFloat, blue: CGFloat) -> UIColor {
let color = UIColor(red: red / 255, green: green / 255, blue: blue / 255, alpha: 1.0)
return color
}
}
Please, give me a piece of advice on how to realize it as an extension.

Answer 1

One main thing I can see in your code, is that you try to do the drawing in viewDidLoad. Don't do that, on top of other problems, the frame size is not properly set yet at that moment. If you want the UIView to do the drawing, then derive a class from UIView, and do the drawing in the draw method of that class.
If you want the radialGradientLayer CALayer that you created to do the drawing (it currently is just empty), then derive a subclass from CALayer, and implement its drawInContext method.