Box2d中的碰撞检测失败

我想检测身体之间的碰撞，一个身体有圆形，30个有凸体 . 也许问题是因为检测到圆与凸之间的碰撞？请帮忙，找不到2天的答案......我有3个班： Player ， ConctactListener 和 level1 （我在哪里创建多边形） .

在 Player 中我设置了类型 kGameObjectPlayer ：

- (id) init {
        if ((self = [super init])) {
            type = kGameObjectPlayer;
        }
        return self;
    }
-(void) createBox2dObject:(b2World*)world {


    b2BodyDef playerBodyDef;
    playerBodyDef.type = b2_dynamicBody;

    playerBodyDef.position.Set(self.position.x/PTM_RATIO, self.position.y/PTM_RATIO);
    playerBodyDef.userData = self;
    playerBodyDef.fixedRotation = true;

    body = world->CreateBody(&playerBodyDef);

    b2CircleShape circleShape;
    circleShape.m_radius = 0.7;
    b2FixtureDef fixtureDef;
    fixtureDef.shape = &circleShape;
    fixtureDef.density = 1.0f;
    fixtureDef.friction = 1.0f;
    fixtureDef.restitution =  0.0f;
    body->CreateFixture(&fixtureDef);
}

在 ContactListener ：

void ContactListener::BeginContact(b2Contact *contact) {
    GameObject *o1 = (GameObject*)contact->GetFixtureA()->GetBody()->GetUserData();
    GameObject *o2 = (GameObject*)contact->GetFixtureB()->GetBody()->GetUserData();

    if (IS_PLATFORM(o1, o2) && IS_PLAYER(o1, o2)) {
        CCLOG(@"-----> Player made contact with platform!");
    }
}

void ContactListener::EndContact(b2Contact *contact) {
    GameObject *o1 = (GameObject*)contact->GetFixtureA()->GetBody()->GetUserData();
    GameObject *o2 = (GameObject*)contact->GetFixtureB()->GetBody()->GetUserData();

    if (IS_PLATFORM(o1, o2) && IS_PLAYER(o1, o2)) {
        CCLOG(@"-----> Player lost contact with platform!");
    }
}

在 level1 中，我创建的静态多边形应该是玩家应该接触的地面 .

- (void) drawStaticPolygons
    {
        GameObject *ground = [[GameObject alloc] init];
        [ground setType:kGameObjectGround];

        //1st polygon
        b2Vec2 vertices1[4];
        vertices1[0].Set(0, 1);
        vertices1[1].Set(0, 0);
        vertices1[2].Set(16, 0);
        vertices1[3].Set(16, 1);

        b2BodyDef myBodyDef1;
        myBodyDef1.type = b2_staticBody;
        myBodyDef1.userData = ground;

        b2PolygonShape polygonShape1;
        polygonShape1.Set(vertices1, 4); 

        b2FixtureDef myFixtureDef1;
        myFixtureDef1.shape = &polygonShape1; //change the shape of the fixture
        myBodyDef1.position.Set(0,0); 
        b2Body *staticBody1 = world->CreateBody(&myBodyDef1);
        staticBody1->CreateFixture(&myFixtureDef1); //add a fixture to the body

        //2nd polygon
        ....
        //n polygon
    }

问题是如何让ContactListener知道我的多边形是 kGameObjectGround ？