I'm trying to change the fillColor of a CAShapeLayer when the layer it's contained in is touched. I'm able to change the background color of the tapped layer like this:

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
CALayer *layer = [(CALayer *)self.view.layer.presentationLayer hitTest:point];
layer = layer.modelLayer;
layer.backgroundColor = [UIColor blueColor].CGColor;
}

This turns the background of "layer" blue as expected. My problem is how do I change the color of the CAShapelayer inside "layer"? Thanks!