Recognize touch on specific side of 3d cube

Question

The cube is made of 6 CALayers which are then added to a single CATransformLayer. This transformLayer -and with it, the cube- are rotatable using touch input.

Problem: I want to be able to recognize which side of the cube is touched by the user.

I have tried this code:

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
CGPoint location = [[touches anyObject] locationInView:self];

        if ([self.side1 containsPoint: [self.layer convertPoint:location toLayer:self.side1]]) {
            NSLog(@"Side 1");}
        if ([self.side2 containsPoint: [self.layer convertPoint:location toLayer:self.side2]]) {
            NSLog(@"Side 2"); }
        if ([self.side3 containsPoint: [self.layer convertPoint:location toLayer:self.side3]]) {
            NSLog(@"Side 3 "); }
        if ([self.side4 containsPoint: [self.layer convertPoint:location toLayer:self.side4]]) {
            NSLog(@"Side 4"); }
        if ([self.side5 containsPoint: [self.layer convertPoint:location toLayer:self.side5]]) {
            NSLog(@"Side 5"); }
        if ([self.side6 containsPoint: [self.layer convertPoint:location toLayer:self.side6]]) {
            NSLog(@"Side 6");
    }

But the cube seems to be mapped on a 2D space: when i touch side 1, not only side 1 is recognized but also the side behind it (e.g. side 4).

how can I make sure that only the side which is nearer to the user (higher z coordinate) is selected?

Answer 1

Have you tried using the hitTest method on the presentation layer of the sides? aka something along the lines of:

CALayer* touchedLayer = [[self.side4.presentationLayer hitTest:location] modelLayer];
if(touchedLayer!=nil){
   NSLog(@"Side 4");
}

Thoughts?