objective c - cocos2d collision detection BOOL Flag -

i trying head round collision detection, here game details: have character can move freely around screen , fire bullets enemies generated off screen , ‘hero’ can shoot them (when bullets , enemies created stored in arrays , removed @ collision) if enemy makes contact hero nothing happens, life removed on contact , believe done via collision detection. using

(cgrectintersectsrect([hero boundingbox], [enemy boundingbox]))  

but not collisions detected , 3 detected. believe caused multiple collisions detected objects pass through each other. have tried use bool flag don’t believe doing correctly, code:

.h bool collision; .m -(void)update:(cctime)deltatime {         if (collision == no) {         if (cgrectintersectsrect([hero boundingbox], [enemy boundingbox])) {             cclog(@”collision detected!!!!!!!!!!!!!!!!”);             collision = yes;         }     } }  

is best way deal collision detection , if how implement bool flag?

you set boolean on yes when collide , no when stop colliding know next time when it's new collision.

if (cgrectintersectsrect([hero boundingbox], [enemy boundingbox])) {     cclog(@”collision detected!!!!!!!!!!!!!!!!”);     if(!collision) {         // remove life     }     collision = yes; } else {     collision = no; }