.h文件

///创建单例类+ (instancetype)sharedInstance;+ (instancetype) alloc __attribute__((unavailable("call sharedInstance instead")));+ (instancetype) new __attribute__((unavailable("call sharedInstance instead")));- (instancetype) copy __attribute__((unavailable("call sharedInstance instead")));- (instancetype) mutableCopy __attribute__((unavailable("call sharedInstance instead")));复制代码

.m文件

///单例类+ (instancetype)sharedInstance{        static POrderGoodsInfoManager *manager = nil;    static dispatch_once_t onceToken;    dispatch_once(&onceToken, ^{        manager = [[super allocWithZone:NULL] init];    });    return manager;}复制代码