- (NSDictionary *)toDictionary{    NSMutableDictionary *dictionaryFormat = [NSMutableDictionary dictionary];        //  取得当前类类型    Class cls = [self class];        unsigned int ivarsCnt = 0;    //　获取类成员变量列表，ivarsCnt为类成员数量    Ivar *ivars = class_copyIvarList(cls, &ivarsCnt);        //　遍历成员变量列表，其中每个变量都是Ivar类型的结构体    for (const Ivar *p = ivars; p < ivars + ivarsCnt; ++p)    {        Ivar const ivar = *p;                //　获取变量名        NSString *key = [NSString stringWithUTF8String:ivar_getName(ivar)];        // 若此变量未在类结构体中声明而只声明为Property，则变量名加前缀 ‘_‘下划线        // 比如 @property(retain) NSString *abc;则 key == _abc;                //　获取变量值        id value = http://www.mamicode.com/[self valueForKey:key];>
遍历类成员