CAGradientLayer and scrollViewTexturedBackgroundColor - iphone

Question

I'm trying to use CAGradientLayer to fade foreground controls against the background textured view.
So in a nutshell, I have a view with the bg color as scrollViewTexturedBackgroundColor. I have a view on top of that, whose contents I'd like to fade at the border into the background view's color.
CAGradientLayer* gradient = [CAGradientLayer layer];
gradient.frame = self->scrollableCanvas.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor scrollViewTexturedBackgroundColor] CGColor], (id)[[UIColor scrollViewTexturedBackgroundColor] CGColor], nil];
[gradient setStartPoint:CGPointMake(0.90, 1)];
[gradient setEndPoint:CGPointMake(1, 1)];
[[self->scrollableCanvas layer] addSublayer:gradient];
[[self->scrollableCanvas layer] setMasksToBounds:YES];
Unfortunately, CAGradientLayer doesn't seem to support UIColors as pattern images.
any ideas how I can achieve a simple border fade effect for the subview?
thanks

Answer 1

You can use a little trick:
//create normal UIImageView
UIImageView* iv = [[[UIImageView alloc] initWithImage: [UIImage imageNamed :#"bg_png.png"]] autorelease];
[superview addSubview: iv];
//draw gradient on top
UIView *view = [[[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)] autorelease];
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = view.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor colorWithWhite: 1.0 alpha: 0.0] CGColor], (id)[[UIColor colorWithWhite: 1.0 alpha: 1.0] CGColor], nil];
[view.layer insertSublayer:gradient atIndex:0];
[superview addSubview: view];

Answer 2

I made a category on UILabel that adds gradient at the end of the label using Max's answer.
If you need, here it is:
#import "UILabel+GradientEnding.h"
#implementation UILabel (GradientEnding)
- (void)addGradientEnding
{
//draw gradient on top
UIView *gradientAlphaView = [[UIView alloc] initWithFrame:CGRectMake(self.frame.size.width - 80.0, 0, 80.0, self.frame.size.height)];
UIColor *startColor = RGBA(0xf7f7f7, 0);
UIColor *endColor = RGBA(0xf7f7f7, 1);
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = gradientAlphaView.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[startColor CGColor], (id)[endColor CGColor], nil];
gradient.startPoint = CGPointMake(0, 0.5);
gradient.endPoint = CGPointMake(1.0, 0.5);
[gradientAlphaView.layer insertSublayer:gradient atIndex:0];
[self addSubview:gradientAlphaView];
}
#end
But you should use your own colors. And use this define:
#define RGBA(rgbValue, opacity) [UIColor \
colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 \
green:((float)((rgbValue & 0xFF00) >> 8))/255.0 \
blue:((float)(rgbValue & 0xFF))/255.0 alpha:opacity]