IOS第二天多线程-04简化单例模式

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

// .m文件
#define HMSingletonM(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:(NSZone *)zone {     return _instance; } 

@implementation HMMovieTool
HMSingletonM(MovieTool)
@end