設計模式之單例模式

class Singleton
{
public:
	~Singleton();
	static Singleton* instance()
	{
		if (pInstance == nullptr)
		{
			pInstance = new Singleton();
		}
		return pInstance;
	}
protected:
	Singleton* pInstance;
	Singleton(){cout<<"Singleton"<<endl;}
	~Singleton()
	{
		delete pInstance;
		pInstance = NULL;
	}
};

//Obj-c 單例設計模式
#define DECLARE_SINGLETON(cls_name, method_name)\
    + (cls_name*)method_name;

#define IMPLEMENT_SINGLETON(cls_name, method_name)\
    + (cls_name *)method_name {\
        static cls_name *method_name;\
        static dispatch_once_t onceToken;\
        dispatch_once(&onceToken, ^{\
            method_name = [[cls_name alloc] init];\
        });\
        return method_name;\
    }