ios - 如何使用 NSDictionary 收集嵌套在数组中的 JSON 数据

Question

我有以下 JSON:

{
0: 200,
error: false,
campaigns: {
current_campaigns: [
                {
                id: "1150",
                campaign_type_id: "1",
                campaign_type: "Type",
                title: "Name (with type) ",
                url: "http://www.example.com",
                special: null,
                campaign_instructions: "Here's what you do",
                pay_description: "",
                start: "2013-10-14 00:00:00",
                end: "2014-03-31 23:59:59"
                },
                {
                id: "1151",
                campaign_type_id: "1",
                campaign_type: "Type",
                title: "Name (with type) ",
                url: "http://www.example.com",
                special: null,
                campaign_instructions: "Here's what you do",
                pay_description: "",
                start: "2013-10-14 00:00:00",
                end: "2014-03-31 23:59:59"
                },
    ],
    new_campaigns: [
                {
                id: "1152",
                campaign_type_id: "1",
                campaign_type: "Type",
                title: "Name (with type) ",
                url: "http://www.example.com",
                special: null,
                campaign_instructions: "Here's what you do",
                pay_description: "",
                start: "2013-10-14 00:00:00",
                end: "2014-03-31 23:59:59"
                }

    ]
}

还有下面的代码

NSURL *theJSON = [NSURL URLWithString:@"http://somejsonurl"];
NSURLRequest *request = [NSURLRequest requestWithURL:theJSON];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError){
    NSError *errorJson = nil;
NSDictionary *dataDictionary = [NSJSONSerialization JSONObjectWithData:data options:0     error:&errorJson];

    NSArray *campaigns = dataDictionary[@"campaigns"];

    for (NSDictionary *campaignList in campaigns) {
        NSLog(@"Call gave: %@", campaigns);
    }

我将如何最终记录 current_campaign 标题？ 我试过了

   NSLog(@"%@", [campaignList objectForKey:@"title"]);
   NSLog(@"%@", campaigns[@"title"] );

并没有成功。我是 Objective C 的新手，无法理解如何使用 NSArray 和 NSDictionary 深入研究 JSON。任何帮助将不胜感激!

Answer 1

关于 JSON 最容易记住的事情是每次你看到括号“[”，这意味着 Array 的开始，而“]”是结束.每次看到大括号“{”时，表示 Dictionary 的开头，而“}”表示结尾。

因此，在您的示例中，campaigns 是一个 Dictionary 元素，其中包含另一个 Dictionary (current_campaigns) 字典 的数组。每个 Dictionaries 都有一个名为 title 的 key。

所以长版(未经测试):

NSDictionary *campaigns = [dataDictionary objectForKey:@"campaigns"];
NSArray *currentCampaigns = [campaigns objectForKey:@"current_campaigns"];
for (NSDictionary *thisCampaign in currentCampaigns) {
    NSLog(@"title: %@", [thisCampaign objectForKey:@"title"]);
}