问当我试图进行碰撞检测时，接收到EXC_BAD_ACCESS信号

EN

    B2Body *body[NUM_SEGMENT];
    CCSprite *ball;

    ball = [CCSprite spriteWithFile:@"Ball1.2.png"];
    ball.tag = 1;


    for(int i=0;i<NUM_SEGMENT;i++){
        float theta = deltaAngle*i;
        float x = radius * cosf(theta);
        float y = radius * sinf(theta);
        b2Vec2 circlePosition = b2Vec2(x/PTM_RATIO,y/PTM_RATIO);
        b2BodyDef bodyDef;
        bodyDef.type = b2_dynamicBody;
        bodyDef.position = (center + circlePosition);
        bodyDef.userData = &ball;
        body[i] = world->CreateBody(&bodyDef);
        outerBodyFixture[i]=body[i]->CreateFixture(&fixtureDef);
        [bodies addObject:[NSValue valueWithPointer:body[i]]];
    }

CCSprite *tile;

tile = [layer1 tileAt:ccp(i, j)];
tile.tag = 0;
b2BodyDef tileDef;
tileDef.type = b2_staticBody;
tileDef.position.Set((tile.position.x+(tile.contentSize.width/2))/(PTM_RATIO), (tile.position.y + (tile.contentSize.height/2))/PTM_RATIO);
tileDef.userData = &tile;
tileBody = world->CreateBody(&tileDef);

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 = (__bridge CCSprite *) bodyA->GetUserData();

        CCSprite *spriteB = (__bridge CCSprite *) bodyB->GetUserData();


            printf("contact :%d \n",spriteB.tag);
        }
    }