CATransformLayer Opacity Problem

viewDidLoad

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // Make TransformLayer
    CATransformLayer *transformLayer = [CATransformLayer layer];
    transformLayer.frame = self.view.bounds;
    transformLayer.anchorPoint = CGPointMake(0, 0);
    
    // Make red layer
    CALayer *redLayer = [CALayer layer];
    redLayer.bounds = transformLayer.bounds;
    redLayer.backgroundColor = [UIColor redColor].CGColor;

    // Make blue layer
    CALayer *blueLayer = [CALayer layer];
    blueLayer.bounds = transformLayer.bounds;
    blueLayer.backgroundColor = [UIColor blueColor].CGColor;
    
    // Push the red layer back a tiny bit so it's truly behind the blue layer
    redLayer.transform = CATransform3DMakeTranslation(0, 0, -0.001);
    // Flip the red layer around
    redLayer.transform = CATransform3DRotate(redLayer.transform, M_PI, 0, 1, 0);
    
    // Setting doubleSided to NO prevents the back color from bleeding through when transformLayer's opacity is adjusted
    redLayer.doubleSided = NO;
    blueLayer.doubleSided = NO;
    
    [transformLayer addSublayer:redLayer];
    [transformLayer addSublayer:blueLayer];
    
    [transformLayer setOpacity:0.5];
    
    [self.view.layer addSublayer:transformLayer];
}