Use macro to define singleton mode in ARC mode (GCD implementation of Singleton mode)

. h file # define HMSINGLETONH (name) + (instancetype) shared# #name;//. m file # define HMSINGLETONM (name) static ID _instance;< c1/>+ (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: (Nszone *) zone {     return _instance;}

Use macro to define singleton mode in ARC mode (GCD implementation of Singleton mode)