When you want to give the background color to the view, but you want to add more colors and get the gradient effect, you need to add a layer to view,
which we are going to create, in few lines of code.

• Create a CAGradientLayer

var gradientLayer: CAGradientLayer = {
   let gradientLayer =CAGradientLayer()
   gradientLayer.colors = [#Color1, #Color2] //note: colors you want to use
   gradientLayer.startPoint = CGPoint(x:0 y:0)
   gradientLayer.endPoint = CGPoint(x:1 y:1)
   gradientLayer.frame= CGRect.zero
   return gradientLayer
} ()

• Add gradientLayer to the view layer

currentView.layer.addSublayer(gradientLayer)

• Set frame of the gradientLayer

gradientLayer.frame = currentView.bounds