Cocos2d iphone jointDef.在box2d cocos2d中初始化后崩溃

我有一条船和一个码头，当我按下码头时，我希望有一个连接它们的接头

- (void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

UITouch *myTouch = [touches anyObject];
CGPoint location = [myTouch locationInView:[myTouch view]];
location = [[CCDirector sharedDirector] convertToGL:location];
b2Vec2 locationWorld = b2Vec2(location.x/PTM_RATIO, location.y/PTM_RATIO);

if (_dockFixture->TestPoint(locationWorld)) {

    b2DistanceJointDef _myJDef;
    _myJDef.Initialize(_shipBody, _dockBody, _shipBody->GetWorldCenter(),_dockBody->GetWorldCenter());
    (b2DistanceJoint*) _world->CreateJoint(&_myJDef);

}

}

我一点击dock，cocos2d和iphonesimualtor就在没有登录的情况下崩溃了

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我是个新手，怎么了？我是否也应该发布这两个主体的代码？

以调试模式运行应用程序。当您的应用程序将崩溃时-运行调试器并查看调用堆栈以确定问题所在