How to Apply Gradient to background view of iOS Swift App

Question

I'm trying to apply a gradient as the background color of a View (main view of a storyboard). The code runs, but nothing changes. I'm using xCode Beta 2 and Swift.

Here's the code:

class Colors {
  let colorTop = UIColor(red: 192.0/255.0, green: 38.0/255.0, blue: 42.0/255.0, alpha: 1.0)
  let colorBottom = UIColor(red: 35.0/255.0, green: 2.0/255.0, blue: 2.0/255.0, alpha: 1.0)

  let gl: CAGradientLayer

  init() {
    gl = CAGradientLayer()
    gl.colors = [ colorTop, colorBottom]
    gl.locations = [ 0.0, 1.0]
  }
}

then in the view controller:

  let colors = Colors()

  func refresh() {
        view.backgroundColor = UIColor.clearColor()
        var backgroundLayer = colors.gl
        backgroundLayer.frame = view.frame
        view.layer.insertSublayer(backgroundLayer, atIndex: 0)
      }
    }
  }

Answer 1

Xcode 11 • Swift 5.1

---

You can design your own Gradient View as follow:

@IBDesignable
public class Gradient: UIView {
    @IBInspectable var startColor:   UIColor = .black { didSet { updateColors() }}
    @IBInspectable var endColor:     UIColor = .white { didSet { updateColors() }}
    @IBInspectable var startLocation: Double =   0.05 { didSet { updateLocations() }}
    @IBInspectable var endLocation:   Double =   0.95 { didSet { updateLocations() }}
    @IBInspectable var horizontalMode:  Bool =  false { didSet { updatePoints() }}
    @IBInspectable var diagonalMode:    Bool =  false { didSet { updatePoints() }}

    override public class var layerClass: AnyClass { CAGradientLayer.self }

    var gradientLayer: CAGradientLayer { layer as! CAGradientLayer }

    func updatePoints() {
        if horizontalMode {
            gradientLayer.startPoint = diagonalMode ? .init(x: 1, y: 0) : .init(x: 0, y: 0.5)
            gradientLayer.endPoint   = diagonalMode ? .init(x: 0, y: 1) : .init(x: 1, y: 0.5)
        } else {
            gradientLayer.startPoint = diagonalMode ? .init(x: 0, y: 0) : .init(x: 0.5, y: 0)
            gradientLayer.endPoint   = diagonalMode ? .init(x: 1, y: 1) : .init(x: 0.5, y: 1)
        }
    }
    func updateLocations() {
        gradientLayer.locations = [startLocation as NSNumber, endLocation as NSNumber]
    }
    func updateColors() {
        gradientLayer.colors = [startColor.cgColor, endColor.cgColor]
    }
    override public func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        super.traitCollectionDidChange(previousTraitCollection)
        updatePoints()
        updateLocations()
        updateColors()
    }

}