iOS hitTest withEvent - ios

Question

I'm attempting to get the reference to a UImageView that is underneath a masked UIImageView using hitTest withEvent. Here is what I have that is not working:
UIView A that contains 3 UIImageViews as subviews: panelOne, panelTwo, and panelThree. panelThree is takes up the entire frame but is masked into a triangle, revealing parts of panels one and two. So I need to detect when a user taps outside of that rectangle and send the touch to the appropriate UIImageView.
Code: (CollagePanel is a subclass of UIImageView)
-(void)triangleInASquare
{
CGSize size = self.frame.size;
CollagePanel *panelOne = [[CollagePanel alloc] initWithFrame:CGRectMake(0,0, size.width/2, size.height)];
panelOne.panelScale = panelOne.frame.size.width/self.frame.size.width;
panelOne.backgroundColor = [UIColor greenColor];
CollagePanel *panelTwo = [[CollagePanel alloc] initWithFrame:CGRectMake(size.width/2,0, size.width/2, size.height)];
panelTwo.panelScale = panelOne.frame.size.width/self.frame.size.width;
panelTwo.backgroundColor = [UIColor purpleColor];
CollagePanel *panelThree = [[CollagePanel alloc] initWithFrame:CGRectMake(0,0, size.width, size.height)];
panelThree.backgroundColor = [UIColor orangeColor];
UIBezierPath* trianglePath = [UIBezierPath bezierPath];
[trianglePath moveToPoint:CGPointMake(0, panelThree.frame.size.height)];
[trianglePath addLineToPoint:CGPointMake(panelThree.frame.size.width/2,0)];
[trianglePath addLineToPoint:CGPointMake(panelThree.frame.size.width, panelTwo.frame.size.height)];
[trianglePath closePath];
// Mask the panels's layer to triangle.
CAShapeLayer *triangleMaskLayer = [CAShapeLayer layer];
[triangleMaskLayer setPath:trianglePath.CGPath];
triangleMaskLayer.strokeColor = [[UIColor whiteColor] CGColor];
panelThree.layer.mask = triangleMaskLayer;
//Add border
CAShapeLayer *borderLayer = [CAShapeLayer layer];
borderLayer.strokeColor = [[UIColor whiteColor] CGColor];
borderLayer.fillColor = [[UIColor clearColor] CGColor];
borderLayer.lineWidth = 6;
[borderLayer setPath:trianglePath.CGPath];
[panelThree.layer addSublayer:borderLayer];
NSMutableArray *tempArray = [[NSMutableArray alloc] init];
[tempArray addObject:panelOne];
[tempArray addObject:panelTwo];
[tempArray addObject:panelThree];
[self addGestureRecognizersToPanelsInArray:tempArray];
[self addPanelsFromArray:tempArray];
self.panelArray = tempArray;
}
-(void)handleTap: (UITapGestureRecognizer*) recognizer //coming from panel.imageView
{
CGPoint tapPoint = [recognizer locationInView:self];
NSLog(#"Location in self: %#", NSStringFromCGPoint(tapPoint));
NSLog(#"self.subviews: %#", self.subviews);
UIView *bottomView = [self hitTest:tapPoint withEvent:nil];
NSLog(#"Bottom View: %#", bottomView);
}
The NSLog of bottomView is always panelThree (the topmost panel). From what I understand the hit test should be returning the "bottom most" subview.

Answer 1

you understand wrong. it will return the view that recognizes itself as touched and is nearest to your finger, nearer to the top.
If a view shall not recognize itself as touch for a certain point, you need to overwrite
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
for that view.
I think Ole Begemann's Shapped Button is a great example how to do so.
In your project this method could determine, if a point lies within the paths: CGPathContainsPoint.
Your pointInside:withEvent: might look like this:
#import "CollagePanel.h"
#import <QuartzCore/QuartzCore.h>
#implementation CollagePanel
//
// ...
//
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
CGPoint p = [self convertPoint:point toView:[self superview]];
if(self.layer.mask){
if (CGPathContainsPoint([(CAShapeLayer *)self.layer.mask path], NULL, p, YES) )
return YES;
}else {
if(CGRectContainsPoint(self.layer.frame, p))
return YES;
}
return NO;
}
#end