Method for animating images (like a movie) on iPhone without using MPMoviePlayer

[CATransaction begin];
[CATransaction setValue:[NSNumber numberWithFloat:0.25f] // 1/4th of a second per frame
    		     forKey:kCATransactionAnimationDuration];
[mainLayer replaceSublayer:[imageLayers objectAtIndex:oldImageIndex] with:[imageLayers objectAtIndex:newImageIndex]];
[CATransaction commit];