Cocos2d-iphone v3 touch event detection on CCNode with children - ios

Question

I have a CCNode that contains multiple CCSprite children.
I would like to receive touch events in my parent CCNode if any of the children have been touched.
This behaviour seems like it should be supported, I may be missing something.
My solution is to setUserInteractionEnabled = YES on all children and bubble the event up to the parent.
I do this by subclassing the CCSprite class overriding their method :
- (void) touchBegan:(UITouch *)touch withEvent:(UIEvent *)event
{
[super touchBegan:touch withEvent:event];
}
I am wondering if there is a more elegant, simple and generic way of accomplishing the same behaviour ?

Answer 1

You could override hitTestWithWorldPos: of your 'containing' node, either calling hitTestWithWorldPos on specific children or, iterating through all children as you see fit. Perhaps something like this:
-(BOOL) hitTestWithWorldPos:(CGPoint)pos
{
BOOL hit = NO;
hit = [super hitTestWithWorldPos:pos];
for(CCNode *child in self.children)
{
hit |= [child hitTestWithWorldPos:pos];
}
return hit;
}
edit: just to be clear, then you would only need to setUserInteractionEnabled for the container, and only process the touch using the touch events of the containing node.
edit2:
so, I thought about it for a bit more and here's a quick category you can add that will enable a quick hit test for all children of a node recursively.
CCNode+CCNode_RecursiveTouch.h
#import "CCNode.h"
#interface CCNode (CCNode_RecursiveTouch)
{
}
-(BOOL) hitTestWithWorldPos:(CGPoint)worldPos forNodeTree:(id)parentNode shouldIncludeParentNode:(BOOL)includeParent;
#end
CCNode+CCNode_RecursiveTouch.m
#import "CCNode+CCNode_RecursiveTouch.h"
#implementation CCNode (CCNode_RecursiveTouch)
-(BOOL) hitTestWithWorldPos:(CGPoint)worldPos forNodeTree:(id)parentNode shouldIncludeParentNode:(BOOL)includeParent
{
BOOL hit = NO;
if(includeParent) {hit |= [parentNode hitTestWithWorldPos:worldPos];}
for( CCNode *cnode in [parentNode children] )
{
hit |= [cnode hitTestWithWorldPos:worldPos];
(cnode.children.count)?(hit |= [self hitTestWithWorldPos:worldPos forNodeTree:cnode shouldIncludeParentNode:NO]):NO; // on recurse, don't process parent again
}
return hit;
}
#end
usage would just be .. in the containing class, override hitTestWithWorldPos like this:
-(BOOL) hitTestWithWorldPos:(CGPoint)pos
{
BOOL hit = NO;
hit = [self hitTestWithWorldPos:pos forNodeTree:self shouldIncludeParentNode:NO];
return hit;
}
and of course, don't forget to include the category header.

Answer 2

-(void) touchBegan:(UITouch *)touch withEvent:(UIEvent *)event
{
//Do whatever you like...
//Bubble the event up to the next responder...
[[[CCDirector sharedDirector] responderManager] discardCurrentEvent];
}