mutable method is send to imutable object

NSMutableDictionary = [[NSMutableDictionary alloc]init];

yiJianSelectItmes = [NSMutableDictionary dictionaryWithDictionary:[defaults objectForKey:@"yiJianQueryItems"]];//得到的是可變的

yiJianSelectItmes ＝ (NSMutableDictionary *)[defaults objectForKey:@"yiJianQueryItems"];//雖然強制轉換了 但是得到的依然我的是不可變的，所以會報錯mutable method is send to imutable object