gistfile1.m

    [image setWantsLayer:YES];
    CALayer *flayer = [image layer];
    [flayer removeAllAnimations];
    
    [backImage setWantsLayer:YES];
    CALayer *blayer = [backImage layer];
    [blayer removeAllAnimations];
    
    NSView *superView = [image superview];
    [superView setWantsLayer:YES];  
    
    	CATransformLayer *transformLayer = [CATransformLayer layer];
	transformLayer.frame = image.bounds;
    	transformLayer.anchorPointZ = image.bounds.size.height;
    	transformLayer.anchorPoint = CGPointMake(0.5, 0.0);
	[transformLayer addSublayer:flayer];
	[transformLayer addSublayer:blayer];
	[superView.layer addSublayer:transformLayer];
    
    //rotate the layer to transition to
	CATransform3D transform = CATransform3DIdentity;
    	transform = CATransform3DRotate(transform, DEGREES_TO_RADIANS(90) , 1, 0, 0);
    	transform = CATransform3DTranslate(transform, 0, -image.bounds.size.height,0);
	blayer.transform = transform;
	
    //animate transition to the rotated layer
	CABasicAnimation *transformAnimation = [CABasicAnimation animation];
	
    	transform = CATransform3DIdentity;
	transformAnimation.fromValue = [NSValue valueWithCATransform3D:transform];
	
	transform = CATransform3DIdentity;
    	transform = CATransform3DRotate(transform, DEGREES_TO_RADIANS(-90) , 1, 0, 0);
	transformAnimation.toValue = [NSValue valueWithCATransform3D:transform];
    
	transformAnimation.duration = 9.7;
	[transformLayer addAnimation:transformAnimation forKey:@"transform"];