How to cut up image based on coordinates – Photoshop

I have a question related to cutting up an image to know which part is tapped by the user. It’s a rather simple exercise for some, I think, but I’ve been cracking my head over this and can’t find a proper way.

What I would like to do is tap a body part on this image and have the device tell me what body part it is:

But I have absolutely no clue on how to program this.

• I’ve been thinking on setting an array of outline CGPoints for every body part, but how to get those? Photoshop coordinates? And then calculate the touched point onto the closest CGPoint?

• Somebody gave me the idea to cut up the image in the different zones, different images for every body part. But here the problem is that every image is a rectangle, which makes it very hard to know what exactly got touched. Would also need an array of points, especially for the overlapping images.

• Another person told me this would only be possible using SpriteKit.

Let me know, smart peeps 🙂

UPDATE:
I figured it out! I’m making a lot of arrays that contain the points to the hand, the legs, … An example:

CGPoint p1 = CGPointMake(x + 432, y + 200);
CGPoint p2 = CGPointMake(x + 523, y + 188);
CGPoint p3 = CGPointMake(x + 530, y + 277);
CGPoint p4 = CGPointMake(x + 432, y + 277);
CGPoint p5 = CGPointMake(x + 523, y + 367);
CGPoint p6 = CGPointMake(x + 432, y + 354);
CGPoint p7 = CGPointMake(x + 325, y + 355);
CGPoint p8 = CGPointMake(x + 296, y + 362);

NSArray *handL = [NSArray arrayWithObjects:
                              [NSValue valueWithCGPoint:p1],
                              [NSValue valueWithCGPoint:p2],
                              [NSValue valueWithCGPoint:p3],
                              [NSValue valueWithCGPoint:p4], nil];
[shapes addObject:@{@"name":NSLocalizedString(@"Left Hand", @""), @"points":handL}];

NSArray *handR = [NSArray arrayWithObjects:
                              [NSValue valueWithCGPoint:p5],
                              [NSValue valueWithCGPoint:p6],
                              [NSValue valueWithCGPoint:p7],
                              [NSValue valueWithCGPoint:p8], nil];
[shapes addObject:@{@"name":NSLocalizedString(@"Right Hand", @""), @"points": handR}];

Afterwards in I read these values and layer them:

NSArray *shapes = [[NumbersHelper sharedNumbersHelper] getScreenThreeShapes];
    for (int outside = 0; outside < [shapes count]; outside++) {
        CAShapeLayer *shape = [[CAShapeLayer alloc] init];
        [self.scrollView.layer addSublayer:shape];
        shape.opacity = 0.5;
        shape.lineWidth = 2;
        shape.lineJoin = kCALineJoinRound;

        NSArray *points = [[[shapes valueForKey:@"points"] allObjects] objectAtIndex:outside];
        UIBezierPath *path = [[UIBezierPath alloc] init];
        for (int inside = 0; inside < points.count; inside++) {
            if (inside == 0) {
                [path moveToPoint:[[points objectAtIndex:inside] CGPointValue]];
            } else {
                [path addLineToPoint:[[points objectAtIndex:inside] CGPointValue]];
            }
        }
        [path closePath];
        shape.path = [path CGPath];
        shape.name = [[[shapes valueForKey:@"name"] allObjects] objectAtIndex:outside];
    }

When the user taps the view I do this:

- (void)tappedOnView:(UITapGestureRecognizer *)sender
{

if ([sender locationInView:self.scrollView].x > 2048 && [sender locationInView:self.scrollView].x < 3072) {
    screenTwoTouchedPoint = [sender locationInView:self.scrollView];

    CGPoint touchPoint = [sender locationInView:self.scrollView];
    NSString *name;
    for (id sublayers in self.scrollView.layer.sublayers) {
        if ([sublayers isKindOfClass:[CAShapeLayer class]]) {
            CAShapeLayer *shape = sublayers;
            if (CGPathContainsPoint(shape.path, 0, touchPoint, YES)) {
                name = shape.name;
                break;
            }
        }
    }
    [self tappedBody:sender onPart:name];
}

}