如何从iOS中的字典中获取值 [英] How to get values from a dictionary in iOS

问题描述

我是 iOS 的新手。我创建了一个登录页面，一切正常。我使用 JSON 来检查用户名和密码，并以字典格式从服务器获得响应。我想从字典中提取值并在我的程序中检查它们。
我从服务器得到的回复是：

I am new to iOS. I created a login page and everything works fine. I used JSON for checking username and password and got the response from server in a dictionary format. I want to extract the values from the dictionary and check them in my program. The response which I get from the server is:

json: {
        error = 0;
        msg = "";
        value = {
                  user = false;
                };
      };

首先，我想检查带有 键的值是否有错误 0 或 1 的。然后我想用密钥 user 检查值。我不知道应该如何编码来检查它。有人可以帮忙吗？

First I want to check if the value with the key error is 0 or 1. Then I want to check the value with the key user. I don't know how I should code to check it. Can anyone help?

我试过的代码如下：

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSString *respString = [[NSString alloc] initWithData:loginJSONData encoding:NSUTF8StringEncoding];

    SBJsonParser *objSBJSONParser = [[SBJsonParser alloc] init];

    NSDictionary *json = [[NSDictionary alloc] initWithDictionary:[objSBJsonParser objectWithString:respString]];

    NSLog(@"json: %@",json);

    NSString *error = [json objectForKey:@"error"];

    NSLog(@"error: %@", error);

    if ([error isEqualToString:@"o"])
    {
        NSLog(@"login successful");
    }
    else
    {
        NSLog(@"login fail");
    }
}

推荐答案

使用现代的Objective-C，访问数组和字典中的东西变得更容易。

Using modern Objective-C, accessing things in arrays and dictionaries become easier.

你应该使用以下语法：

ID< NSObject的> value =字典[@key];

同样，

ID< NSObject的> value = array [1]; // 1是索引

将上述内容应用于问题：

Applying the above to the question:

NSString * error = json [@error];

NSDictionary * value = json [@value];

BOOL user = [json [@value] [@ user] boolValue];

如上所述，允许嵌套，但这不是一个好习惯。

As in the above line, nesting is allowed, but it is not a good practice.

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