ios - 如何在 Objective C 中从 NSArray 中获取元素

Question

我正在使用公交时刻表 API，并希望根据用户当前位置显示附近的公交车站。我已经通过 url 获得了 JSON 响应并将 JSON 解析为 NSArray。 NSArray 看起来像这样。

{
    result =         {
        distance = "0.00003292029";
        lat = "-37.92091";
        "location_name" = "Monash Medical Centre/Clayton Rd ";
        lon = "145.120682";
        "route_type" = 2;
        "stop_id" = 16518;
        suburb = Clayton;
        "transport_type" = bus;
    };
    type = stop;
},
    {
    result =         {
        distance = "0.00003728643";
        lat = "-37.92227";
        "location_name" = "Monash Surgical Private Hospital/291 Clayton Rd ";
        lon = "145.1202";
        "route_type" = 2;
        "stop_id" = 24348;
        suburb = Clayton;
        "transport_type" = bus;
    };
    type = stop;
},
    {
    result =         {
        distance = "0.00003804303";
        lat = "-37.9230766";
        "location_name" = "Clayton Railway Station/Clayton Rd ";
        lon = "145.120209";
        "route_type" = 2;
        "stop_id" = 22809;
        suburb = Clayton;
        "transport_type" = bus;
    };
    type = stop;
},
    {
    result =         {
        distance = "0.00003976311";
        lat = "-37.9186172";
        "location_name" = "Monash Specialist Centre/Clayton Rd ";
        lon = "145.121033";
        "route_type" = 2;
        "stop_id" = 22807;
        suburb = Clayton;
        "transport_type" = bus;
    };
    type = stop;
},
    {
    result =         {
        distance = "0.00004085229";
        lat = "-37.9186478";
        "location_name" = "Dixon St/Clayton Rd ";
        lon = "145.120911";
        "route_type" = 2;
        "stop_id" = 13889;
        suburb = Clayton;
        "transport_type" = bus;
    };
    type = stop;
}

)

我的问题是如何从这个 NSArray 中获取纬度和经度。我写了这些代码，但它返回 nil。

    NSMutableArray *coordinateLatit = [[NSMutableArray alloc]init];
for (int i = 0; i<nearbyStop.count; i++) {
    NSString *latit = [[nearbyStop objectAtIndex:1] objectForKey:@"lat"];
    if(latit == nil)
    {
        NSLog(@"there is no data");
    }
    else
    {
    [coordinateLatit addObject:latit];
    }
}

我还想在 MKMapView 上显示停靠点(使用 NSArray 的经度和纬度)，我应该如何实现 MKLocalSearchRequest如果有人能帮助我，我将不胜感激!

Answer 1

您的代码忽略了额外的嵌套 result 级别。

NSMutableArray *coordinateLatit=[[NSMutableArray alloc]init];

for(NSDictionary *d in nearbyStop)
{
    NSString    *latit=d[@"result"][@"lat"];

    if(lat) [coordinateLatit addObject:latit];
}