解析 JSON 时出错

Question

晚上好！

我需要一些帮助来解析来自 Google 方向的 JSON。 我有以下代码来获取 html_instructions 值：

NSString *myRawJson = [[NSString alloc] initWithContentsOfURL:
                           [NSURL URLWithString:@"http://maps.google.com/maps/api/directions/json?origin=-15.802737,-47.87963&destination=-15.851783,-47.954593&sensor=true"]];

    // Create a dictionary from the JSON string
    NSDictionary *results = [myRawJson JSONValue];

    NSArray *resultarr = [results objectForKey:@"routes"];
    NSString *string;
    //NSArray *subarray;

    for(NSDictionary *di in resultarr){
        NSLog(@"loop");
        NSDictionary *subdic = [[di objectForKey:@"legs"] objectForKey:@"steps"];
        string = [subdic objectForKey:@"html_instructions"];
        NSLog(@"%@",string);
    }
    (...)

当我运行它时，我得到以下错误

-[__NSArrayM objectForKey:]：无法识别的选择器发送到实例 0x6d9b3e0 2011-11-02 22:53:02.110 APSplitSample[1470:11603] * 由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因：“-[__NSArrayM objectForKey:]：无法识别的选择器发送到实例 0x6d9b3e0 '

这是 JSON（可以看到完整运行上面的 url）：

{
   "routes" : [
      {
         "bounds" : {
            "northeast" : {
               "lat" : -15.79760,
               "lng" : -47.879710
            },
            "southwest" : {
               "lat" : -15.874160,
               "lng" : -47.958310
            }
         },
         "copyrights" : "Dados cartográficos ©2011 MapLink",
         "legs" : [
            {
               "distance" : {
                  "text" : "16,0 km",
                  "value" : 15989
               },
               "duration" : {
                  "text" : "16 minutos",
                  "value" : 945
               },
               "end_address" : "Estr. Epia - Candangolândia, Brasília - DF, Brasil",
               "end_location" : {
                  "lat" : -15.851770,
                  "lng" : -47.95470
               },
               "start_address" : "Via de Ligação Se/ne - Brasília, DF, Brasil",
               "start_location" : {
                  "lat" : -15.802960,
                  "lng" : -47.879710
               },
               "steps" : [
                  {
                     "distance" : {
                        "text" : "0,6 km",
                        "value" : 625
                     },
                     "duration" : {
                        "text" : "1 min",
                        "value" : 59
                     },
                     "end_location" : {
                        "lat" : -15.800940,
                        "lng" : -47.885150
                     },
                     "html_instructions" : "Siga na direção \u003cb\u003eoeste\u003c/b\u003e na \u003cb\u003eVia de Ligação Se/ne\u003c/b\u003e em direção à \u003cb\u003eVia Bs S Um\u003c/b\u003e",
                     "polyline" : {
                        "points" : "nom_BdofcHa@hB[rACRId@Kf@g@|BOl@AFKb@Kd@i@~BaArCKZiA`DKVCFGLCFKX"
                     },
                     "start_location" : {
                        "lat" : -15.802960,
                        "lng" : -47.879710
                     },
                     "travel_mode" : "DRIVING"
                  },
                  {
                     "distance" : {
                        "text" : "0,1 km",
                        "value" : 101
                     },
 (...)

有人可以帮忙吗？！ 提前致谢！

Answer 1

您好，我希望使用此代码可能对您有所帮助

    NSDictionary *mainDict=[requeststring JSONValue];

    //NSLog(@"maindict values is %d",[mainDict count]);


    NSArray *routesArray=[mainDict objectForKey:@"routes"];

        if ([routesArray count]>0)
        {


    NSDictionary *routeDict=[routesArray objectAtIndex:0];

    NSArray *legsarray=[routeDict objectForKey:@"legs"];



    NSDictionary *legsdict=[legsarray objectAtIndex:0];







        NSDictionary *distDict=[legsdict objectForKey:@"distance"];

        NSString *distncestring=[distDict objectForKey:@"text"];

        NSDictionary *timeDict=[legsdict objectForKey:@"duration"];

        NSString *time=[timeDict objectForKey:@"text"];




    NSDictionary *startlatdict=[legsdict objectForKey:@"start_location"];
    float latt=[[startlatdict objectForKey:@"lat"] floatValue];
    float long=[[startlatdict objectForKey:@"lng"] floatValue];






    NSArray *stepsarray=[legsdict objectForKey:@"steps"];

        for (int i=0; i<[stepsarray count]; i++)
        {

            NSDictionary *stepsdict=[stepsarray objectAtIndex:i];

            NSDictionary *endlattdict=[stepsdict objectForKey:@"end_location"];

            float lang1=[[endlattdict objectForKey:@"lat"] floatValue];
            float long1=[[endlattdict objectForKey:@"lng"] floatValue];


NSString *instStr =[stepsdict objectForKey:@"html_instructions"];

        NSLog(@"html_instructions%@",instStr);




        }

}

此代码可帮助您获取 google map json 数据的所有信息

祝你好运

Answer 2

结果：

[di objectForKey:@"legs"]

似乎是另一个数组，而不是字典。所以当你添加时

[[di objectForJet:@"legs"] objectForKey:@"steps"]

您正在将 objectForKey 消息发送到 NSArray。

试试这样的：

NSArray *legs = [di objectForKey@"legs];
for (NSDictionary *subdic in legs) {
    string = [subdic objectForKey:@"html_instructions"];
    NSLog(@"%@",string);
}