objective-c - NSMutableArray 到 NSUserDefults 不保存

Question

我正在以这种方式读取和写入 NSuserdefults 数组:

indexDelete = button.tag;

                    NSUserDefaults *currentDefaults = [NSUserDefaults standardUserDefaults];
                    NSData *dataRepresentingSavedArray = [currentDefaults objectForKey:@"save"];
                    if (dataRepresentingSavedArray != nil)
                    {
                        NSArray *oldSavedArray = [NSKeyedUnarchiver unarchiveObjectWithData:dataRepresentingSavedArray];
                        if (oldSavedArray != nil)
                            myIntegers = [[NSMutableArray alloc] initWithArray:oldSavedArray];
                        else
                            myIntegers = [[NSMutableArray alloc] init];
                    }

                    [myIntegers addObject:[NSNumber numberWithInteger:indexDelete]];

                    NSLog (@"Array myIntegers: %@", myIntegers);

                    [[NSUserDefaults standardUserDefaults] setObject:[NSKeyedArchiver archivedDataWithRootObject:myIntegers] forKey:@"save"];

如果我坚持下去，一切都会很好:

myIntegers = [[NSMutableArray alloc] init];

括号之外，因为即使数据在那里，也没有正确写入或读取:

我收到此错误:-[NSKeyedUnarchiver initForReadingWithData:]:数据为 NULL

我做错了什么？

Answer 1

改变这个:

[[NSUserDefaults standardUserDefaults] setObject:[NSKeyedArchiver archivedDataWithRootObject:myIntegers] forKey:@"save"];

到

[[NSUserDefaults standardUserDefaults] setObject:myIntegers forKey:@"save"];

如果 myIntegers 将来不会发生变异(更改)。如果要更改，则使用:

[[NSUserDefaults standardUserDefaults] setObject:[NSArray arrayWithArray:myIntegers] forKey:@"save"];

类描述中记录了在用户默认值中保存数组和字典的功能。