iOS White to Transparent Gradient Layer is Gray

Worth pointing out that any other colour will work like this... using a combination of the two answers above....

Objective C

UIColor *colour = [UIColor redColor];
NSArray *colourArray = @[(id)[colour colorWithAlphaComponent:0.0f].CGColor,(id)colour.CGColor]
NSArray *locations = @[@0.2,@0.8];

CAGradientLayer *gradientLayer = [CAGradientLayer layer];
gradientLayer.colors = colourArray;
gradientLayer.locations = locations;
gradientLayer.frame = self.frame;

[self.layer addSublayer:gradientLayer];

Swift 3

let colour:UIColor = .red
let colours:[CGColor] = [colour.withAlphaComponent(0.0).cgColor,colour.cgColor]
let locations:[NSNumber] = [0.2,0.8]

let gradientLayer = CAGradientLayer()
gradientLayer.colors = colours
gradientLayer.locations = locations
gradientLayer.frame = frame

layer.addSublayer(gradientLayer)

In Swift This worked for me,

UIColor.white.withAlphaComponent(0).cgColor

clearColor has a black color channel with an alpha of 0, so I had to use

[UIColor colorWithWhite:1 alpha:0]

and it works fine.