#quartzcore

UIView *view = [[[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 100)] autorelease]; CAGradientLayer *gradient = [CAGradientLayer layer]; gradient.frame = view.bounds; gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor blackColor] CGColor], (id)[[UIColor whiteColor] CGColor], nil]; [view.layer insertSublayer:gradient atIndex:0];

Or

- (void)drawRect:(CGRect)rect { CGContextRef currentContext = UIGraphicsGetCurrentContext(); CGGradientRef glossGradient; CGColorSpaceRef rgbColorspace; size_t num_locations = 2; CGFloat locations[2] = { 0.0, 1.0 }; CGFloat components[8] = { 1.0, 1.0, 1.0, 0.35, // Start color 1.0, 1.0, 1.0, 0.06 }; // End color rgbColorspace = CGColorSpaceCreateDeviceRGB(); glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations); CGRect currentBounds = self.bounds; CGPoint topCenter = CGPointMake(CGRectGetMidX(currentBounds), 0.0f); CGPoint midCenter = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetMidY(currentBounds)); CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, 0); CGGradientRelease(glossGradient); CGColorSpaceRelease(rgbColorspace); }

The default startPoint and endPoint would have the gradient display your colors from top to bottom (which in my mind is a vertical gradient). If you want the gradient to display from left to right (again in my mind this is a horizontal gradient), use this code on your CAGradientLayer:

[gradient setStartPoint:CGPointMake(0.0, 0.5)]; [gradient setEndPoint:CGPointMake(1.0, 0.5)];

A 3D transform is unnecessary.

When I first tried to code this game I went for the QuartzCore API. It was simple and had some speed (over UIView related classes). But I quickly realized that I was running at 20-30 frames per second (the later when things were quiet). 

I knew I had to go for OpenGL someday but it sounded too much firepower to handle a simple 2D sprites game.

So the solution was to use CALayers, which perform most of the work on the GPU and also caches all the sprites as textures, so indirectly its OpenGL but with a simpler API.

I've been running it 60 fps ever since and I feel confident about adding a lot more complexity to the game without sacrificing this important aspect.