What does userInteractionEnabled = NO mean and how does it work? - ios

Question

Cocos 2d-iphone 3.0. I am using this code to detect whether a single sprite is touched
-(void) touchBegan:(UITouch *)touch withEvent:(UIEvent *)event {
CGPoint location = [touch locationInView: [touch view]];
CGPoint convertedlocation = [[CCDirector sharedDirector] convertToGL: location];
CGPoint convertedNodeSpacePoint = [self convertToNodeSpace:convertedlocation];
if (CGRectContainsPoint([_sprite boundingBox],convertedNodeSpacePoint))
{
// Remove sprite
}
}
I have some code inside that should remove some other sprites from parent. Logically, when _sprite
is touched second time, application will crash, because other sprites'v been already removed.
I was trying to make _sprite untouchable using _sprite.userInteractionEnabled = NO;, but this has no effect.
What does userInteractionEnabled mean exactly and how would one use this to facilitate touch detection on sprites.
What is the optimal way of handling touches on sprites in my scene?

Answer 1

There is no way to disable interactions on a ccsprite. What you should do is:
bool firstTimeClicked=false;
-(void) touchBegan:(UITouch *)touch withEvent:(UIEvent *)event {
if(firstTimeClicked==true)
{
return NO;
}
CGPoint location = [touch locationInView: [touch view]];
CGPoint convertedlocation = [[CCDirector sharedDirector] convertToGL: location];
CGPoint convertedNodeSpacePoint = [self convertToNodeSpace:convertedlocation];
if (CGRectContainsPoint([_sprite boundingBox],convertedNodeSpacePoint)) {
firstTimeClicked=true;
}
}

Answer 2

What userInteractionEnabled does
When you set userInteractionEnabled=YES on a sprite that mean that user interaction callbacks are going to get called.
So for example in your scene if you would have userInteractionEnabled=NO your -(void) touchBegan:(UITouch *)touch withEvent:(UIEvent *)event would not get called.
What you we're doing
You were detecting the touches in your scene. And then you we're checking what was under that touch location, so if anything was under there it would be detected.
How to accomplish this properly - subclass your CCSprite
You want to handle these kind of behaviours in custom CCSprite classes, because if not your scenes touchBegan is going to turn into a huge buggy if else switch statement.
Believe me, I have been there.
Here is a code example of what this class could look like :
The .h file
#interface SubclassedSprite : CCSprite
#end
And the .m file
#implementation SubclassedSprite
- (void) onEnter
{
[super onEnter];
self.userInteractionEnabled = YES;
}
- (void) touchBegan:(UITouch *)touch withEvent:(UIEvent *)event
{
CCLOG(#"Touch began on sprite");
// Your code when the Sprite was touched [self removeFromParentAndCleanup:YES];
}
#end
This is the proper, scalable way to handle this.

Answer 3

Below code is without taking an extra BOOL variable and it should work for you:
-(void) touchBegan:(UITouch *)touch withEvent:(UIEvent *)event {
CGPoint location = [touch locationInView: [touch view]];
CGPoint convertedlocation = [[CCDirector sharedDirector] convertToGL: location];
CGPoint convertedNodeSpacePoint = [self convertToNodeSpace:convertedlocation];
if (CGRectContainsPoint([_sprite boundingBox],convertedNodeSpacePoint)) {
if(_sprite.userInteractionEnabled)//Here you can remove the children of _sprite. e.g.
{
//Here run some action or do what you want to do. For e.g.
CCFadeTo *fadeOut = [CCFadeTo actionWithDuration:0.5f opacity:0];
CCCallfuncN *clean = [CCCallFuncN actionWithTarget:self SEL:#selector(cleanSpriteChildren:)];
for(id item in _sprite.children)
if(item)
[item runAction:[CCSequence runActions:fadeOut, clean]];
}
else{//Do your own task while _sprite is untouchable}
}
}
-(void)cleanSpriteChildren:(id)sender
{
[item removeFromParentAndCleanUp:YES]
if(([_sprite children] count) == 0)
_sprite.userInteractionEnabled = YES; //Here make the _sprite touchable again
}