利用JSON检索值的Objective-C [英] Retrieving values from json using objective-c

问题描述

目前我正在试图用JSON但是和Objective-C有一点难度的工作。以下是返回的JSON

  {
    sethostname =（
    {
        封邮件=更新的Apache配置\\ nUpdating的cPanel许可证...完成更新成功\\ nBuilding全局高速缓存的cPanel ...完成。
        状态= 1;
        statusmsg =主机名更改为：a.host.name.com
        警告=（
        ）;
    }）;
}
 

我能够检查响应回来，关键是sethostname但是无论我怎么努力，我不能得到例如状态或statusmsg值。任何人都可以点我在正确的位置。以下是基本的code，我使用检查sethostname被返回。

  NSError * myError =零;
*的NSDictionary解析度= [NSJSONSerialization JSONObjectWithData：应对方案：NSJSONReadingMutableLeaves错误：＆放大器; myError]。
的NSLog（[水库说明]）;
NSArray的* ARR;
ARR = [RES allKeys]
如果（[ARR containsObject：@sethostname]）
{
    的NSLog（@工作）;
}
 

解决方案

当有疑问，写下你的JSON数据的结构。例如：

  {
    sethostname =（
    {
        封邮件=更新的Apache配置\\ nUpdating的cPanel许可证...完成更新成功\\ nBuilding全局高速缓存的cPanel ...完成。
        状态= 1;
        statusmsg =主机名更改为：a.host.name.com
        警告=（
        ）;
    }）;
}
 

（这是NeXTSTEP的属性列表格式，实际上）意味着你有一个顶级的字典。这个顶层字典包含一个名为键 sethostname ，其值是一个数组。该阵列由词典，有一组键，每个键的字典：短信息，状态，statusmsg，警告。 封邮件有一个字符串值，状态有一些价值， statusmsg 有一个字符串值， warns`有一个数组值：

 词典（顶层）
    sethostname（字典数组）
        字典（数组元素）
            封邮件（字符串）
            状态（数）
            statusmsg（字符串）
            警告（阵列）
                ??? （数组元素）
 

在认识这个结构，你的code应该是这样的：

  NSError * myError =零;
*的NSDictionary解析度= [NSJSONSerialization JSONObjectWithData：应对方案：NSJSONReadingMutableLeaves错误：＆放大器; myError]。如果（！RES）{// JSON解析器失败}//字典（顶层）
如果（！[RES isKindOfClass：[NSDictionary的类]）{
    // JSON解析器并没有回词典
}// sethostname（字典数组）
NSArray的* setHostNames = [RES objectForKey：@sethostname];//词典（数组元素）
对于（*的NSDictionary在setHostName setHostNames）{
    //状态（数）
    *的NSNumber状态= [setHostName objectForKey：@状态];    // statusmsg（串）
    * NSString的statusmsg = [setHostName objectForKey：@statusmsg];    ...
}
 

I am currently trying to work with json and objective-c however having a bit of difficulty. The following is the json that is being returned

{
    sethostname =     (
    {
        msgs = "Updating Apache configuration\nUpdating cPanel license...Done. Update succeeded.\nBuilding global cache for cpanel...Done";
        status = 1;
        statusmsg = "Hostname Changed to: a.host.name.com";
        warns =             (
        );
    });
}

I am able to check that the response is coming back and the key is sethostname however no matter what I try I cannot get for example the value of status or statusmsg. Can anyone point me in the right location. The following is basic code I am using to check that sethostname is returned.

NSError *myError = nil;
NSDictionary *res = [NSJSONSerialization JSONObjectWithData:response options:NSJSONReadingMutableLeaves error:&myError];
NSLog([res description]);
NSArray *arr;
arr = [res allKeys];
if ([arr containsObject:@"sethostname"])
{
    NSLog(@"worked");
}

解决方案

When in doubt, write down the structure of your JSON data. For example:

{
    sethostname =     (
    {
        msgs = "Updating Apache configuration\nUpdating cPanel license...Done. Update succeeded.\nBuilding global cache for cpanel...Done";
        status = 1;
        statusmsg = "Hostname Changed to: a.host.name.com";
        warns =             (
        );
    });
}

(which is in NeXTSTEP property list format, actually) means that you have a top-level dictionary. This top-level dictionary contains a key called sethostname whose value is an array. This array is comprised of dictionaries, each dictionary having a set of keys: msgs, status, statusmsg, warns. msgs has a string value, status has a number value, statusmsg has a string value,warns` has an array value:

dictionary (top-level)
    sethostname (array of dictionaries)
        dictionary (array element)
            msgs (string)
            status (number)
            statusmsg (string)
            warns (array)
                ??? (array element)

Having understood this structure, your code should look like:

NSError *myError = nil;
NSDictionary *res = [NSJSONSerialization JSONObjectWithData:response options:NSJSONReadingMutableLeaves error:&myError];

if (!res) { // JSON parser failed }

// dictionary (top-level)
if (![res isKindOfClass:[NSDictionary class]]) {
    // JSON parser hasn't returned a dictionary
}

// sethostname (array of dictionaries)
NSArray *setHostNames = [res objectForKey:@"sethostname"];

// dictionary (array element)
for (NSDictionary *setHostName in setHostNames) {
    // status (number)
    NSNumber *status = [setHostName objectForKey:@"status"];

    // statusmsg (string)
    NSString *statusmsg = [setHostName objectForKey:@"statusmsg"];

    …
}

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