I'm trying to use core image on the iphone. I'm able to composite my colors using quartz to draw an uiview, but i want to separate each component into CALayer (UIview consume more resources).

So i have a white mask i want to use to filter a background bitmap, and i want to try diffrent blending mode. UNfortunately, the layers are only "adding" their colors.

Here is my code :

@implementation WhiteLayerHelper

- (void)drawLayer:(CALayer *)theLayer
        inContext:(CGContextRef)myContext
{
    // draw a white overlay, with special blending and alpha values, so that the saturation can be animated
    CGContextSetBlendMode(myContext,kCGBlendModeSaturation);
    CGContextSetRGBFillColor(myContext,1.0,1.0,1.0,0.9);
    CGContextFillRect(myContext,[UIScreen mainScreen].bounds);

}

@end

And here is the main view drawrect code, where i use my CALayer :

- (void)drawRect:(CGRect)rect {
    //get the drawing context
    CGContextRef myContext = UIGraphicsGetCurrentContext();
    // draw the background
    [self fillContext:myContext withBounds:m_overlayRect withImage:m_currentImage];
    [whiteLayer renderInContext:myContext];

}

Is there something wrong ?