Box2d Body can not destroy when touch with another body - cocos2d-iphone

Question

I am using box2d based game and it detect my player body collied with enemy body but when i write destroybody method for enemy at collied point that time my enemy can not destroy and gives error and my apps crashed.
I show you my code
std::vector<b2Body *>toDestroy;
std::vector<MyContact>::iterator pos;
for(pos = contactListener->_contacts.begin();
pos != contactListener->_contacts.end(); ++pos) {
MyContact contact = *pos;
b2Body *bodyA = contact.fixtureA->GetBody();
b2Body *bodyB = contact.fixtureB->GetBody();
if (bodyA->GetUserData() != NULL && bodyB->GetUserData() != NULL)
{
CCSprite *spriteA = (CCSprite *) bodyA->GetUserData();
CCSprite *spriteB = (CCSprite *) bodyB->GetUserData();
if (spriteA.tag == 1 && spriteB.tag == 2)
{
// SpriteA = PlayerSprite
// SpriteB = EnemySprite
NSString *t=[NSString stringWithFormat:#"Game Over"];
label.string=t;
[self removeChild:spriteB cleanup:YES];
world->DestroyBody(bodyB);
}
else if (spriteA.tag == 2 && spriteB.tag == 1)
{
//toDestroy.push_back(bodyB);
NSLog(#"Enemy Touch");
}
}
}
Here my spriteB can not destroy.
One more thing is enemy sprite is into the Enemy.mm file.
Please help me i am stuck with this problem.
Thanks in advance

Answer 1

Your making a fundamental error of handling enemy contact with player different from player contact with enemy(its just the order of thing), you should treat both case the same because you cant know what order they arrive.
Also you arent using toDestroy properly.
std::vector<b2Body *>toDestroy;
std::vector<MyContact>::iterator pos;
for(pos = contactListener->_contacts.begin();
pos != contactListener->_contacts.end(); ++pos) {
MyContact contact = *pos;
b2Body *bodyA = contact.fixtureA->GetBody();
b2Body *bodyB = contact.fixtureB->GetBody();
if (bodyA->GetUserData() != NULL && bodyB->GetUserData() != NULL)
{
CCSprite *spriteA = (CCSprite *) bodyA->GetUserData();
CCSprite *spriteB = (CCSprite *) bodyB->GetUserData();
if ((spriteA.tag == 1 && spriteB.tag == 2) ||(spriteA.tag == 2 && spriteB.tag == 1))
{
// SpriteA = PlayerSprite
// SpriteB = EnemySprite
NSString *t=[NSString stringWithFormat:#"Game Over"];
label.string=t;
[self removeChild:spriteB cleanup:YES];
toDestroy.push_back(bodyB);
}
}
}
//iterate and delete everything from toDestroy