CAGradientLayer diagonal gradient

Question

I use the following CAGradientLayer:

let layer = CAGradientLayer()
layer.colors = [
    UIColor.redColor().CGColor,
    UIColor.greenColor().CGColor         


        

Answer 1

Here's the math to fix the endPoint

let width = bounds.width
let height = bounds.height
let dx = endPoint.x - startPoint.x
let dy = endPoint.y - startPoint.y
if width == 0 || height == 0 || width == height || dx == 0 || dy == 0 {
  return
}
let ux = dx * width / height
let uy = dy * height / width
let coef = (dx * ux + dy * uy) / (ux * ux + uy * uy)
endPoint = CGPoint(x: startPoint.x + coef * ux, y: startPoint.y + coef * uy)