Gradient Mask in iOS

Gradient Alpha Mask in iOS

CAGradientLayer *gradientLayer = [CAGradientLayer layer];
NSArray *colors = [NSArray arrayWithObjects:
                   (id)[[UIColor colorWithWhite:0 alpha:0] CGColor],
                   (id)[[UIColor colorWithWhite:0 alpha:1] CGColor],
                   nil];
[gradientLayer setColors:colors];
[gradientLayer setStartPoint:CGPointMake(0.0f, 1.0f)];
[gradientLayer setEndPoint:CGPointMake(0.0f, 0.6f)];
gradientLayer.frame = uiimageview.bounds;
gradientLayer.layer.mask = gradientLayer;

Gradient View

UIImageView *uiimageview = (UIImageView *)[self viewWithTag:100];
if ([[uiimageview.layer sublayers] count] < 1) {
  CAGradientLayer *gradientLayer = [CAGradientLayer layer];
  NSArray *colors = [NSArray arrayWithObjects:
                     (id)[[UIColor colorWithWhite:0 alpha:0.9] CGColor],
                     (id)[[UIColor colorWithWhite:0 alpha:0.1] CGColor],
                     nil];
  [gradientLayer setColors:colors];
  [gradientLayer setStartPoint:CGPointMake(0.0f, 1.0f)];
  [gradientLayer setEndPoint:CGPointMake(0.0f, 0.2f)];
  gradientLayer.frame = uiimageview.bounds;
  [uiimageview.layer insertSublayer:gradientLayer atIndex:0];
}