如何用Object-C解析JSON？

Question

如何用Object-C解析JSON？我对iPhone很陌生。有人能告诉我解析这些数据并获取活动细节、名字和姓氏所遵循的步骤吗？{     "#error": false,      "#data": {         "": {             "activity_id": "35336",              "user_id": "1",              "user_first_name": "Chandra Bhusan",              "user_last_name": "Pandey",              "time": "1300870420",              "activity_details": "Good\n",              "activity_type": "status_update",              "photo_url": "http://184.73.155.44/hcl-meme/QA_TEST/sites/default/files/pictures/picture-1627435117.jpg"         },          "boolean": "1",          "1": {             "1": {                 "photo_1_id": "9755"             },              "activity_id": "35294",              "album_name": "Kalai_new_Gallery",              "user_id": "31",              "album_id": "9754",              "user_first_name": "Kalaiyarasan",              "user_last_name": "Balu",              "0": {                 "photo_0_id": "9756"             },              "time": "1300365758",              "activity_type": "photo_upload",              "photo_url": "http://184.73.155.44/hcl-meme/QA_TEST/"         },          "3": {             "activity_id": "35289",              "user_id": "33",              "user_first_name": "Girija",              "user_last_name": "S",              "time": "1300279636",              "activity_details": "girija Again\n",              "activity_type": "status_update",              "photo_url": "http://184.73.155.44/hcl-meme/QA_TEST/sites/default/files/pictures/picture-33-6361851323080768.jpg"         },

Answer 1

从OSXv10.7和iOS 5的角度来看，现在推荐的第一件事可能是NSJSONSerialization，苹果提供了JSON解析器。如果在运行时发现类不可用，则只使用第三方选项作为后盾。

例如：

NSData *returnedData = ...JSON data, probably from a web request...// probably check here that returnedData isn't nil; attempting// NSJSONSerialization with nil data raises an exception, and who// knows how your third-party library intends to react?if(NSClassFromString(@"NSJSONSerialization")){
    NSError *error = nil;
    id object = [NSJSONSerialization
                      JSONObjectWithData:returnedData
                      options:0
                      error:&error];

    if(error) { /* JSON was malformed, act appropriately here */ }

    // the originating poster wants to deal with dictionaries;
    // assuming you do too then something like this is the first
    // validation step:
    if([object isKindOfClass:[NSDictionary class]])
    {
        NSDictionary *results = object;
        /* proceed with results as you like; the assignment to
        an explicit NSDictionary * is artificial step to get 
        compile-time checking from here on down (and better autocompletion
        when editing). You could have just made object an NSDictionary *
        in the first place but stylistically you might prefer to keep
        the question of type open until it's confirmed */
    }
    else
    {
        /* there's no guarantee that the outermost object in a JSON
        packet will be a dictionary; if we get here then it wasn't,
        so 'object' shouldn't be treated as an NSDictionary; probably
        you need to report a suitable error condition */
    }}else{
    // the user is using iOS 4; we'll need to use a third-party solution.
    // If you don't intend to support iOS 4 then get rid of this entire
    // conditional and just jump straight to
    // NSError *error = nil;
    // [NSJSONSerialization JSONObjectWithData:...}

Answer 2

NSString* path  = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"json"];//将文件内容读取到字符串中，注意编码NSUTF8StringEncoding 防止乱码，NSString* jsonString = [[NSString alloc] initWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];//将字符串写到缓冲区。NSData* jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];NSError *jsonError;id allKeys = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONWritingPrettyPrinted error:&jsonError];for (int i=0; i<[allKeys count]; i++) {
    NSDictionary *arrayResult = [allKeys objectAtIndex:i];
    NSLog(@"name=%@",[arrayResult objectForKey:@"storyboardName"]);}

档案：

 [
  {
  "ID":1,
  "idSort" : 0,
  "deleted":0,
  "storyboardName" : "MLMember",
  "dispalyTitle" : "76.360779",
  "rightLevel" : "10.010490",
  "showTabBar" : 1,
  "openWeb" : 0,
  "webUrl":""
  },
  {
  "ID":1,
  "idSort" : 0,
  "deleted":0,
  "storyboardName" : "0.00",
  "dispalyTitle" : "76.360779",
  "rightLevel" : "10.010490",
  "showTabBar" : 1,
  "openWeb" : 0,
  "webUrl":""
  }
  ]