Question

我对iOS比较陌生，在保存字典并在NSUserDefaults中更新时面临问题...这是我的实现。

if ([[NSUserDefaults standardUserDefaults] objectForKey:@"KEY"]) {
        [[[NSUserDefaults standardUserDefaults] objectForKey:@"KEY"] setObject:someString forKey:otherKey];
    } else {
        [[NSUserDefaults standardUserDefaults] setObject:[self.dictionary setObject:someString forKey:otherKey] forKey:@"KEY"];
    }

我最初在userdefaults中检查＆＃34; KEY，如果该键不存在，我想将字典设置为键的对象＆＃34; KEY＆＃34;而下一次控制来到这里，因为＆＃34; KEY＆＃34;将存在将字典反对＆＃34; KEY＆＃34;并在字典中设置另一个对象。 someString和otherKey来自调用函数。

我得到＆＃34;向id_Nullable＆＃34;类型的参数发送void，我知道setObject想要一些对象，它在这里接收无效，但现在该做什么。我迷路了。

我想我在这里缺乏一些基础知识，请帮助别人。谢谢！

Answer 1

setObject方法返回nil，您尝试在[NSUserDefault standardUserDefaults]中设置。请参阅以下更新的解决方案代码：

if ([[NSUserDefaults standardUserDefaults] objectForKey:@"KEY"]) {
        //'objectForKey' returns nullable id and not NSDictionary, so you can't directly treat as dictionary
        //[[[NSUserDefaults standardUserDefaults] objectForKey:@"KEY"] setObject:someString forKey:otherKey];
        //Change it to below code
        NSDictionary *dict = [NSDictionary dictionaryWithObject:@"someString" forKey:@"KEY"];
        [[NSUserDefaults standardUserDefaults] setObject:dict forKey:@"otherKey"];

    } else {
        //'setObject' method returns nil, which you are trying to set in [NSUserDefault standardUserDefaults]
        //[[NSUserDefaults standardUserDefaults] setObject:[self.dictionary setObject:someString forKey:otherKey] forKey:@"KEY"];
        [self.dictionary setObject:someString forKey:otherKey];
        [[NSUserDefaults standardUserDefaults] setObject:self.dictionary forKey:@"KEY"];

    }

NSMutableDictionary，将void发送到id_Nullable类型的参数

1 个答案: