ios - -[__NSCFDictionary setObject :forKey:]: mutating method sent to immutable object

Question

运行以下代码时，[dict setValue:@"null"forKey:@"name"]; 一直崩溃。我在这里搜索，发现其他帖子是由不使用 NSMutableDictionary 的人引起的。但是我正在使用它。

如果 name 为 null，为什么会在这一行崩溃？

NSMutableArray *tempCustomers = [[NSMutableArray alloc] init];
for (NSMutableDictionary *dict in [[json objectForKey:@"data"] mutableCopy]) {
    if ([dict objectForKey:@"name"] == [NSNull null]) {
        [dict setValue:@"null" forKey:@"name"];
    }
    [tempCustomers addObject:dict];
}

Answer 1

我最终使用了这个。我猜这就是 deepMutableCopy 是什么？

NSMutableArray *tempCustomers = [[NSMutableArray alloc] init];
for (NSMutableDictionary *dict in [[json objectForKey:@"data"] mutableCopy]) {
    if ([dict objectForKey:@"name"] == [NSNull null]) {
        NSMutableDictionary *tempDict = [[NSMutableDictionary alloc] init];
        tempDict = [dict mutableCopy];

        [tempDict setValue:@"null" forKey:@"name"];
        [tempCustomers addObject:tempDict];
    } else {
        [tempCustomers addObject:dict];
    }
}