多线程篇----将ARC和MVC 单例模式 导入同一个头文件

// .h文件
#define HMSingletonH(name) + (instancetype)shared##name;

// .m文件
#if __has_feature(objc_arc)

    #define HMSingletonM(name) \
    static id _instace; \
 \
    + (id)allocWithZone:(struct _NSZone *)zone \
    { \
        static dispatch_once_t onceToken; \
        dispatch_once(&onceToken, ^{ \
            _instace = [super allocWithZone:zone]; \
        }); \
        return _instace; \
    } \
 \
    + (instancetype)shared##name \
    { \
        static dispatch_once_t onceToken; \
        dispatch_once(&onceToken, ^{ \
            _instace = [[self alloc] init]; \
        }); \
        return _instace; \
    } \
 \
    - (id)copyWithZone:(NSZone *)zone \
    { \
        return _instace; \
    }

#else

    #define HMSingletonM(name) \
    static id _instace; \
 \
    + (id)allocWithZone:(struct _NSZone *)zone \
    { \
        static dispatch_once_t onceToken; \
        dispatch_once(&onceToken, ^{ \
            _instace = [super allocWithZone:zone]; \
        }); \
        return _instace; \
    } \
 \
    + (instancetype)shared##name \
    { \
        static dispatch_once_t onceToken; \
        dispatch_once(&onceToken, ^{ \
            _instace = [[self alloc] init]; \
        }); \
        return _instace; \
    } \
 \
    - (id)copyWithZone:(NSZone *)zone \
    { \
        return _instace; \
    } \
 \
    - (oneway void)release { } \
    - (id)retain { return self; } \
    - (NSUInteger)retainCount { return 1;} \
    - (id)autorelease { return self;}

#endif

//系统自带判断条件语句

#if _has_feature(bbjc_arc)

//如果是arc模式，实现这里面的代码

#else

//如果是Mvc模式，实现这里面的代码

#endif