单例 宏 ARC MRC

// ## : 连接字符串和参数

#define singleton_h(name) + (instancetype)shared##name;

#if __has_feature(obj_arc)//ARC

#define singleton_m(name) \

static id _instance; \

+ (id)allocWithZone:(struct _NSZone *)zone \

{ \

    static dispatch_once_t onceToken; \

    dispatch_once(&onceToken, ^{ \

        _instance = [super allocWithZone:zone]; \

    }); \

    return _instance; \

} \

 \

+ (instancetype)shared##name \

{ \

    static dispatch_once_t onceToken; \

    dispatch_once(&onceToken, ^{ \

        _instance = [[self alloc] init]; \

    }); \

    return _instance; \

} \

 \

+ (id)copyWithZone:(struct _NSZone *)zone \

{ \

    return _instance; \

}

#else//非ARC

#define singleton_m(name) \

static id _instance; \

+ (id)allocWithZone:(struct _NSZone *)zone \

{ \

static dispatch_once_t onceToken; \

dispatch_once(&onceToken, ^{ \

_instance = [super allocWithZone:zone]; \

}); \

return _instance; \

} \

\

+ (instancetype)shared##name \

{ \

static dispatch_once_t onceToken; \

dispatch_once(&onceToken, ^{ \

_instance = [[self alloc] init]; \

}); \

return _instance; \

} \

\

- (oneway void)release \

{ \

\

} \

\

- (id)autorelease \

{ \

return _instance; \

} \

\

- (id)retain \

{ \

return _instance; \

} \

\

- (NSUInteger)retainCount \

{ \

return 1; \

} \

\

+ (id)copyWithZone:(struct _NSZone *)zone \

{ \

return _instance; \

}

#endif

单例 宏 ARC MRC

原文：http://www.cnblogs.com/LennyKwok/p/4354857.html