std::function<void(const std::vector<Touch*>&, Event*)> onTouchesBegan;
    std::function<void(const std::vector<Touch*>&, Event*)> onTouchesMoved;
    std::function<void(const std::vector<Touch*>&, Event*)> onTouchesEnded;
    std::function<void(const std::vector<Touch*>&, Event*)> onTouchesCancelled;

bool EventListenerTouchAllAtOnce::checkAvailable()
{
    if (onTouchesBegan == nullptr && onTouchesMoved == nullptr
        && onTouchesEnded == nullptr && onTouchesCancelled == nullptr)
    {
        CCASSERT(false, "Invalid EventListenerTouchAllAtOnce!");
        return false;
    }
    
    return true;
}

EventListenerCustom* EventDispatcher::addCustomEventListener(const std::string &eventName, const std::function<void(EventCustom*)>& callback)
{
	//custom类的事件加入是通过eventName 和 eventcallBack来进行加入的
    EventListenerCustom *listener = EventListenerCustom::create(eventName, callback);
	
	//custom的事件优先级被默觉得1
    addEventListenerWithFixedPriority(listener, 1);
	
    return listener;
}

。

。。

。）

void EventDispatcher::addEventListener(EventListener* listener)
{
	//假设当前Dispatcher正在进行事件Dispatch，则放到toAddList中。
    if (_inDispatch == 0)
    {
        forceAddEventListener(listener);
    }
    else
    {
		// std::vector
        _toAddedListeners.push_back(listener);
    }

    listener->retain();
}

3.2.5 forceAddEventListener

void EventDispatcher::forceAddEventListener(EventListener* listener)
{
    EventListenerVector* listeners = nullptr;
    EventListener::ListenerID listenerID = listener->getListenerID();
	
	//找到该类eventlistener的vector。此处的vector是EventVector
    auto itr = _listenerMap.find(listenerID);
	//假设没有找到，则须要向map中加入一个pair
    if (itr == _listenerMap.end())
    {
        
        listeners = new EventListenerVector();
        _listenerMap.insert(std::make_pair(listenerID, listeners));
    }
    else
    {
        listeners = itr->second;
    }
    //将该类别listenerpush_back进去（这个函数调用的是EventVector的pushback哦）
    listeners->push_back(listener);
    
	//假设优先级是0。则设置为graph。
    if (listener->getFixedPriority() == 0)
    {
		//设置该listenerID的DirtyFlag
		//(setDirty函数能够这样理解，每一个ListenerID都有特定的dirtyFlag。每次进行add操作后，都要更新该ID的flag)
        setDirty(listenerID, DirtyFlag::SCENE_GRAPH_PRIORITY);
        
		//假设是sceneGraph类的事件。则须要处理两个方面：
		//1.将node 与event 关联
		//2.假设该node是执行中的。则须要恢复其事件（由于默认的sceneGraph listener的状态时pause）
		//添加该listener与node的关联
        auto node = listener->getAssociatedNode();
        CCASSERT(node != nullptr, "Invalid scene graph priority!");
        
        associateNodeAndEventListener(node, listener);
        
		//恢复node的执行状态
        if (node->isRunning())
        {
            resumeEventListenersForTarget(node);
        }
    }
    else
    {
        setDirty(listenerID, DirtyFlag::FIXED_PRIORITY);
    }
}

void EventDispatcher::associateNodeAndEventListener(Node* node, EventListener* listener)
{
	//将listener与node关联，先从map中找到与该node相关的listener vector
    std::vector<EventListener*>* listeners = nullptr;
    auto found = _nodeListenersMap.find(node);
    if (found != _nodeListenersMap.end())
    {
        listeners = found->second;
    }
    else
    {
        listeners = new std::vector<EventListener*>();
        _nodeListenersMap.insert(std::make_pair(node, listeners));
    }
    //vector内加入该listener，这里的vector 是std::vector
    listeners->push_back(listener);
}

void EventDispatcher::resumeEventListenersForTarget(Node* target, bool recursive/* = false */)
{
	//恢复Node的执行状态
    auto listenerIter = _nodeListenersMap.find(target);
    if (listenerIter != _nodeListenersMap.end())
    {
        auto listeners = listenerIter->second;
        for (auto& l : *listeners)
        {
            l->setPaused(false);
        }
    }
    // toAdd List中也要进行恢复
    for (auto& listener : _toAddedListeners)
    {
        if (listener->getAssociatedNode() == target)
        {
            listener->setPaused(false);
        }
    }
	//将该Node 与 node的child 都放到dirtyNode中，来记录与event相关的node
    setDirtyForNode(target);
    
    if (recursive)
    {
        const auto& children = target->getChildren();
        for (const auto& child : children)
        {
            resumeEventListenersForTarget(child, true);
        }
    }
}

void EventDispatcher::removeEventListener(EventListener* listener)
{
	//说在前面，移除一个事件的代价比較大，假设没有必要，请不要无故移除事件。
	//删除一个listener的步骤:
    if (listener == nullptr)
        return;

    bool isFound = false;
    
	//lambda函数。函数从std::vector<EventListener*>* listeners 中移除该listener
    auto removeListenerInVector = [&](std::vector<EventListener*>* listeners){
        if (listeners == nullptr)
            return;
        //遍历
        for (auto iter = listeners->begin(); iter != listeners->end(); ++iter)
        {
            auto l = *iter;
            if (l == listener)
            {
				//找到后的处理方法，标记状态位，并处理关联Node
                CC_SAFE_RETAIN(l);
                l->setRegistered(false);
                if (l->getAssociatedNode() != nullptr)
                {
                    dissociateNodeAndEventListener(l->getAssociatedNode(), l);
                    l->setAssociatedNode(nullptr);  // NULL out the node pointer so we don't have any dangling pointers to destroyed nodes.
                }
                //当前没有在分发事件 则直接从listeners中移除该listener（由于标记了状态未。假设此时在分发事件。则会等结束后再移除）
                if (_inDispatch == 0)
                {
                    listeners->erase(iter);
                    CC_SAFE_RELEASE(l);
                }
                
                isFound = true;
                break;
            }
        }
    };
    
    for (auto iter = _listenerMap.begin(); iter != _listenerMap.end();)
    {
		//从listenersmap 中遍历全部。拿出全部的vector
        auto listeners = iter->second;
        auto fixedPriorityListeners = listeners->getFixedPriorityListeners();
        auto sceneGraphPriorityListeners = listeners->getSceneGraphPriorityListeners();

		//从graphList中寻找。
找到后须要更新该listenerID的dirty flag。
        removeListenerInVector(sceneGraphPriorityListeners);
        if (isFound)
        {
            // fixed #4160: Dirty flag need to be updated after listeners were removed.
            setDirty(listener->getListenerID(), DirtyFlag::SCENE_GRAPH_PRIORITY);
        }
		//从fixedList中寻找
        else
        {
            removeListenerInVector(fixedPriorityListeners);
            if (isFound)
            {
                setDirty(listener->getListenerID(), DirtyFlag::FIXED_PRIORITY);
            }
        }
        

		//假设vector在删除后是空的，则须要移除该vector。而且将对应的listenerID从_priorityDirtyFlagMap中移除。
        if (iter->second->empty())
        {
            _priorityDirtyFlagMap.erase(listener->getListenerID());
            auto list = iter->second;
            iter = _listenerMap.erase(iter);
            CC_SAFE_DELETE(list);
        }
        else
        {
            ++iter;
        }
        
        if (isFound)
            break;
    }

    if (isFound)
    {
        CC_SAFE_RELEASE(listener);
    }
	//假设在上述过程中未找到。则从toAddList中寻找
    else
    {
        for(auto iter = _toAddedListeners.begin(); iter != _toAddedListeners.end(); ++iter)
        {
            if (*iter == listener)
            {
                listener->setRegistered(false);
                listener->release();
                _toAddedListeners.erase(iter);
                break;
            }
        }
    }
}

void EventDispatcher::removeEventListenersForListenerID(const EventListener::ListenerID& listenerID)
{
    auto listenerItemIter = _listenerMap.find(listenerID);
    if (listenerItemIter != _listenerMap.end())
    {
        auto listeners = listenerItemIter->second;
        auto fixedPriorityListeners = listeners->getFixedPriorityListeners();
        auto sceneGraphPriorityListeners = listeners->getSceneGraphPriorityListeners();
        
		//啊哦 又是一个lambda函数。将std::vector<EventListener*>* listenerVector中的Listener所有移除
        auto removeAllListenersInVector = [&](std::vector<EventListener*>* listenerVector){
            if (listenerVector == nullptr)
                return;
            
            for (auto iter = listenerVector->begin(); iter != listenerVector->end();)
            {
				//设置要删除的listener状态，清空与其相关的node信息
                auto l = *iter;
                l->setRegistered(false);
                if (l->getAssociatedNode() != nullptr)
                {
                    dissociateNodeAndEventListener(l->getAssociatedNode(), l);
                    l->setAssociatedNode(nullptr);  // NULL out the node pointer so we don't have any dangling pointers to destroyed nodes.
                }
                
                if (_inDispatch == 0)
                {
                    iter = listenerVector->erase(iter);
                    CC_SAFE_RELEASE(l);
                }
                else
                {
                    ++iter;
                }
            }
        };
        
		//两种类型的事件哦
        removeAllListenersInVector(sceneGraphPriorityListeners);
        removeAllListenersInVector(fixedPriorityListeners);
        
        // Remove the dirty flag according the 'listenerID'.
        // No need to check whether the dispatcher is dispatching event.
        _priorityDirtyFlagMap.erase(listenerID);
        
        if (!_inDispatch)
        {
            listeners->clear();
            delete listeners;
            _listenerMap.erase(listenerItemIter);
        }
    }
    
	//toAddList 的清理，真可怜，还没来得及进入家门就要被扫地出门了么。。。。
    for (auto iter = _toAddedListeners.begin(); iter != _toAddedListeners.end();)
    {
        if ((*iter)->getListenerID() == listenerID)
        {
            (*iter)->setRegistered(false);
            (*iter)->release();
            iter = _toAddedListeners.erase(iter);
        }
        else
        {
            ++iter;
        }
    }
}

void EventDispatcher::removeEventListenersForType(EventListener::Type listenerType)
{
    if (listenerType == EventListener::Type::TOUCH_ONE_BY_ONE)
    {
        removeEventListenersForListenerID(EventListenerTouchOneByOne::LISTENER_ID);
    }
    else if (listenerType == EventListener::Type::TOUCH_ALL_AT_ONCE)
    {
        removeEventListenersForListenerID(EventListenerTouchAllAtOnce::LISTENER_ID);
    }
    else if (listenerType == EventListener::Type::MOUSE)
    {
        removeEventListenersForListenerID(EventListenerMouse::LISTENER_ID);
    }
    else if (listenerType == EventListener::Type::ACCELERATION)
    {
        removeEventListenersForListenerID(EventListenerAcceleration::LISTENER_ID);
    }
    else if (listenerType == EventListener::Type::KEYBOARD)
    {
        removeEventListenersForListenerID(EventListenerKeyboard::LISTENER_ID);
    }
    else
    {
        CCASSERT(false, "Invalid listener type!");
    }
}

void EventDispatcher::removeCustomEventListeners(const std::string& customEventName)
{
    removeEventListenersForListenerID(customEventName);
}

void EventDispatcher::removeAllEventListeners()
{
    bool cleanMap = true;
    std::vector<EventListener::ListenerID> types(_listenerMap.size());
    
    for (const auto& e : _listenerMap)
    {
        if (_internalCustomListenerIDs.find(e.first) != _internalCustomListenerIDs.end())
        {
            cleanMap = false;
        }
        else
        {
            types.push_back(e.first);
        }
    }

    for (const auto& type : types)
    {
        removeEventListenersForListenerID(type);
    }
    
    if (!_inDispatch && cleanMap)
    {
        _listenerMap.clear();
    }
}

ok，让我们静静赞赏源代码吧。

void EventDispatcher::dispatchEvent(Event* event)
{
    if (!_isEnabled)
        return;
    
	//为dirtyNodesVector中的dirtyNode更新Scene Flag。

    updateDirtyFlagForSceneGraph();
    
    
    DispatchGuard guard(_inDispatch);
    
	//特殊touch事件，转到特殊的touch事件处理
    if (event->getType() == Event::Type::TOUCH)
    {
        dispatchTouchEvent(static_cast<EventTouch*>(event));
        return;
    }
    
	//依据事件的类型。获取事件的ID
    auto listenerID = __getListenerID(event);
    
	//依据事件ID，将该类事件进行排序（先响应谁）
    sortEventListeners(listenerID);
    
    auto iter = _listenerMap.find(listenerID);
    if (iter != _listenerMap.end())
    {
        auto listeners = iter->second;
        //该类事件的lambda函数
        auto onEvent = [&event](EventListener* listener) -> bool{
			//设置event的target
            event->setCurrentTarget(listener->getAssociatedNode());
			//调用响应函数
            listener->_onEvent(event);
			//返回是否已经停止
            return event->isStopped();
        };
        
		//将该类事件的listeners 和 该类事件的 lambda函数传给该函数
        dispatchEventToListeners(listeners, onEvent);
    }
    
	//更新该事件相关的listener
    updateListeners(event);
}

void EventDispatcher::dispatchEventToListeners(EventListenerVector* listeners, const std::function<bool(EventListener*)>& onEvent)
{
    bool shouldStopPropagation = false;
    auto fixedPriorityListeners = listeners->getFixedPriorityListeners();
    auto sceneGraphPriorityListeners = listeners->getSceneGraphPriorityListeners();
    
	//总体操作流程分为三个部分，处理优先级<0，=0,>0三个部分
    ssize_t i = 0;
    // priority < 0
    if (fixedPriorityListeners)
    {
        CCASSERT(listeners->getGt0Index() <= static_cast<ssize_t>(fixedPriorityListeners->size()), "Out of range exception!");
        
        if (!fixedPriorityListeners->empty())
        {
            for (; i < listeners->getGt0Index(); ++i)
            {
                auto l = fixedPriorityListeners->at(i);
				// onEvent（l）的操作调用了event的callBack，而且会返回是否停止，假设停止后，则将shouldStopPropagation标记为true
				//在其后面的listeners则不会响应到该事件（这里能够看出触摸事件是怎样被吞噬的）
                if (l->isEnabled() && !l->isPaused() && l->isRegistered() && onEvent(l))
                {
                    shouldStopPropagation = true;
                    break;
                }
            }
        }
    }
    
    if (sceneGraphPriorityListeners)
    {
        if (!shouldStopPropagation)
        {
            // priority == 0, scene graph priority
            for (auto& l : *sceneGraphPriorityListeners)
            {
                if (l->isEnabled() && !l->isPaused() && l->isRegistered() && onEvent(l))
                {
                    shouldStopPropagation = true;
                    break;
                }
            }
        }
    }

    if (fixedPriorityListeners)
    {
        if (!shouldStopPropagation)
        {
            // priority > 0
            ssize_t size = fixedPriorityListeners->size();
            for (; i < size; ++i)
            {
                auto l = fixedPriorityListeners->at(i);
                
                if (l->isEnabled() && !l->isPaused() && l->isRegistered() && onEvent(l))
                {
                    shouldStopPropagation = true;
                    break;
                }
            }
        }
    }
}

void EventDispatcher::dispatchTouchEvent(EventTouch* event)
{
	//先将EventListeners排序
    sortEventListeners(EventListenerTouchOneByOne::LISTENER_ID);
    sortEventListeners(EventListenerTouchAllAtOnce::LISTENER_ID);
    
    auto oneByOneListeners = getListeners(EventListenerTouchOneByOne::LISTENER_ID);
    auto allAtOnceListeners = getListeners(EventListenerTouchAllAtOnce::LISTENER_ID);
    
    // If there aren't any touch listeners, return directly.
    if (nullptr == oneByOneListeners && nullptr == allAtOnceListeners)
        return;
    
	//mutableTouches是用来处理allAtOnce的
    bool isNeedsMutableSet = (oneByOneListeners && allAtOnceListeners);
    
	//这些touch都来自该事件
    const std::vector<Touch*>& originalTouches = event->getTouches();
    std::vector<Touch*> mutableTouches(originalTouches.size());
    std::copy(originalTouches.begin(), originalTouches.end(), mutableTouches.begin());

    //
    // process the target handlers 1st
    //
    if (oneByOneListeners)
    {
        auto mutableTouchesIter = mutableTouches.begin();
        auto touchesIter = originalTouches.begin();
        //遍历touches，每个touch都来自于同一个事件
        for (; touchesIter != originalTouches.end(); ++touchesIter)
        {
            bool isSwallowed = false;

			//事件处理的lambda函数
            auto onTouchEvent = [&](EventListener* l) -> bool { // Return true to break
                EventListenerTouchOneByOne* listener = static_cast<EventListenerTouchOneByOne*>(l);
                
                // Skip if the listener was removed.
                if (!listener->_isRegistered)
                    return false;
             
                event->setCurrentTarget(listener->_node);
                //claimed代表该listener是否接收了该touch（Began返回true or false）
                bool isClaimed = false;
                std::vector<Touch*>::iterator removedIter;
                
				//依据eventNode的不同，会调用不同的callBack函数
                EventTouch::EventCode eventCode = event->getEventCode();
                
                if (eventCode == EventTouch::EventCode::BEGAN)
                {
					//调用began
                    if (listener->onTouchBegan)
                    {
                        isClaimed = listener->onTouchBegan(*touchesIter, event);
                        if (isClaimed && listener->_isRegistered)
                        {
							//返回true后 将该touch放入该listener的claimedTouches
                            listener->_claimedTouches.push_back(*touchesIter);
                        }
                    }
                }
				//假设是后三个move end cancel
                else if (listener->_claimedTouches.size() > 0
                         && ((removedIter = std::find(listener->_claimedTouches.begin(), listener->_claimedTouches.end(), *touchesIter)) != listener->_claimedTouches.end()))
                {
                    isClaimed = true;
                    //调用对应的callBack
                    switch (eventCode)
                    {
                        case EventTouch::EventCode::MOVED:
                            if (listener->onTouchMoved)
                            {
                                listener->onTouchMoved(*touchesIter, event);
                            }
                            break;
                        case EventTouch::EventCode::ENDED:
                            if (listener->onTouchEnded)
                            {
                                listener->onTouchEnded(*touchesIter, event);
                            }
                            if (listener->_isRegistered)
                            {
                                listener->_claimedTouches.erase(removedIter);
                            }
                            break;
                        case EventTouch::EventCode::CANCELLED:
                            if (listener->onTouchCancelled)
                            {
                                listener->onTouchCancelled(*touchesIter, event);
                            }
                            if (listener->_isRegistered)
                            {
                                listener->_claimedTouches.erase(removedIter);
                            }
                            break;
                        default:
                            CCASSERT(false, "The eventcode is invalid.");
                            break;
                    }
                }
                
                // If the event was stopped, return directly.
                if (event->isStopped())
                {
                    updateListeners(event);
                    return true;
                }
                
                CCASSERT((*touchesIter)->getID() == (*mutableTouchesIter)->getID(), "");
                
				//假设接收该touch而且须要吞噬该touch。会有两个影响
				//1.Touches（standard 触摸机制）的触摸操作都接收不到该touch了
				//2.由于返回值是true，在调用dispatchEventToListeners时。在该node之后的node将会不再接收该touch
                if (isClaimed && listener->_isRegistered && listener->_needSwallow)
                {
                    if (isNeedsMutableSet)
                    {
                        mutableTouchesIter = mutableTouches.erase(mutableTouchesIter);
                        isSwallowed = true;
                    }
                    return true;
                }
                
                return false;
            };
            
            //结合上面的dispatchEventToListeners的源代码分析。能够看出新版本号的OneByOne touch机制是这种：
			//1.listener依据Node的优先级排序后。依次响应。
值得注意的是，新版本号的优先级是依据Node的global Zorder来的。而不是2.x的触摸优先级。

			//2.当TouchEvent Began来了之后，全部的listener会依次影响Touch Began。
然后再依次响应Touch Move...而不是一个listener响应完
			//began move end之后 轮到下一个listener响应的顺序。
			//3.吞噬操作仅仅有发生在began return true后才干够发生
            dispatchEventToListeners(oneByOneListeners, onTouchEvent);
            if (event->isStopped())
            {
                return;
            }
            
            if (!isSwallowed)
                ++mutableTouchesIter;
        }
    }
    
    //
    // process standard handlers 2nd
    //
	//相比于OneByOne。AllAtOnce要简单很多。值得注意的是被吞噬的touch也不会被AllAtOnce响应到
    if (allAtOnceListeners && mutableTouches.size() > 0)
    {
        
        auto onTouchesEvent = [&](EventListener* l) -> bool{
            EventListenerTouchAllAtOnce* listener = static_cast<EventListenerTouchAllAtOnce*>(l);
            // Skip if the listener was removed.
            if (!listener->_isRegistered)
                return false;
            
            event->setCurrentTarget(listener->_node);
            
            switch (event->getEventCode())
            {
                case EventTouch::EventCode::BEGAN:
                    if (listener->onTouchesBegan)
                    {
                        listener->onTouchesBegan(mutableTouches, event);
                    }
                    break;
                case EventTouch::EventCode::MOVED:
                    if (listener->onTouchesMoved)
                    {
                        listener->onTouchesMoved(mutableTouches, event);
                    }
                    break;
                case EventTouch::EventCode::ENDED:
                    if (listener->onTouchesEnded)
                    {
                        listener->onTouchesEnded(mutableTouches, event);
                    }
                    break;
                case EventTouch::EventCode::CANCELLED:
                    if (listener->onTouchesCancelled)
                    {
                        listener->onTouchesCancelled(mutableTouches, event);
                    }
                    break;
                default:
                    CCASSERT(false, "The eventcode is invalid.");
                    break;
            }
            
            // If the event was stopped, return directly.
            if (event->isStopped())
            {
                updateListeners(event);
                return true;
            }
            
            return false;
        };
        
        dispatchEventToListeners(allAtOnceListeners, onTouchesEvent);
        if (event->isStopped())
        {
            return;
        }
    }
    
    updateListeners(event);
}

void EventDispatcher::dispatchCustomEvent(const std::string &eventName, void *optionalUserData)
{
    EventCustom ev(eventName);
    ev.setUserData(optionalUserData);
    dispatchEvent(&ev);
}