#define singleton_h(name) + (instancetype)shared##name; #if __has_feature(obj_arc) #define singleton_m(name)static id _instance;+ (instancetype)shared##name{static dispatch_once_t onceToken;dispatch_once(&onceToken, ^{_instance = [[self alloc] init];});return _instance;}+ (id)allocWithZone:(struct _NSZone *)zone{static dispatch_once_t onceToken;dispatch_once(&onceToken, ^{_instance = [super allocWithZone:zone];});return _instance;}+ (id)copyWithZone:(struct _NSZone *)zone{return _instance;} #else #define singleton_m(name)static id _instance;+ (instancetype)shared##name{ static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instance = [[self alloc] init]; }); return _instance;}+ (id)allocWithZone:(struct _NSZone *)zone{ static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instance = [super allocWithZone:zone]; }); return _instance;}+ (id)copyWithZone:(struct _NSZone *)zone{ return _instance;}- (oneway void)release{}- (id)autorelease{ return _instance;}- (id)retain{ return _instance;}- (NSUInteger)retainCount{ return 1;} #endif