strange contact between bodies - cocos2d-iphone

Question

I have a strange problem.
the shot of my players, when it collides with a body, destroys it without problems, but, when it hits the two bodies at once, it crashes.
shooting player
b2Body *shooting = [_lhelper newBodyWithUniqueName:#"shoot" world:_world];
CCSprite *shootingSprite = (CCSprite *)shootingBody->GetUserData();
shootingBody.position = pos;
shootingBody->SetTransform(b2Vec2(pos.x/PTM_RATIO,
pos.y/PTM_RATIO),
CC_DEGREES_TO_RADIANS(angle));
contact
if([spriteA tag] == ENEMY && [spriteB tag] == SHOT)
{
int animIdx = [(NSNumber*)[spriteA userData] intValue];
if(animIdx < 2)
{
[spriteA setTextureRect:MY_RECTS[animIdx]];
[spriteA setUserData:[NSNumber numberWithInt:animIdx+1]];
}
else
{
[objectThatWillBeDeleted addObject:[NSValue valueWithPointer:bodyA]];
}
[objectThatWillBeDeleted addObject:[NSValue valueWithPointer:bodyB]];
}
else if([spriteB tag] == ENEMY && [spriteA tag] == SHOT)
{
int animIdx = [(NSNumber*)[spriteB userData] intValue];
if(animIdx < 2)
{
[spriteB setTextureRect:MY_RECTS[animIdx]];
[spriteA setUserData:[NSNumber numberWithInt:animIdx+1]];
}
else
{
[objectThatWillBeDeleted addObject:[NSValue valueWithPointer:bodyB]];
}
[objectThatWillBeDeleted addObject:[NSValue valueWithPointer:bodyA]];
}
update
std::vector<Contact>::iterator pos;
for(pos = _contactListener->_contacts.begin();
pos != _contactListener->_contacts.end(); ++pos)
{
Contact contact = *pos;
//[self checkBodies2:&contact];
}
for(NSValue* val in objectThatWillBeDeleted)
{
b2Body* body = (b2Body*)[val pointerValue];
[_lhelper removeBody:body];
}
[objectThatWillBeDeleted removeAllObjects];
}
}
I do not understand where the error.

Answer 1

I do not understand where the error either because you didn't say where it crashes :)
But I would guess you are trying to destroy the same body twice.
When the shot hits two enemies in the same time step, the shot body gets added to the objectThatWillBeDeleted list twice. You just need to make that list unique before you destroy the contents of it.