• 自定義的類如果不想通過(guò) [[Class alloc] init] 來(lái)初始化一個(gè)類，可以如下

-(instancetype)init
{
    @throw [NSException exceptionWithName:NSInternalInconsistencyException reason:@"Must use initWithName: age: gender:" userInfo:nil];
}

或

-(instancetype)init
{
    return [self initWithName:@"Roy" age:18 gender:GenderMan];
}

• 通過(guò)實(shí)現(xiàn) description 方法對(duì)象打印

-(NSString *)description
{
    return [NSString stringWithFormat:@"<%@ : %p, %@, %lu,%lu>",[self class],self,_name,(unsigned long)_age,(unsigned long)_gender];
}