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Chris Holloway
2,427 PointsParsing JSON data - a dictionary with only 1 key?
I am downloading JSON data for display in a UILabel. It appears that the JSON data I am downloading via an API is a dictionary of one key, where the "value" of the key contains a sub-dictionary.
For starters, I am attempting to display only one value of the JSON data.
Here is the raw JSON output (pretty simple):
{"weatherObservation":{"clouds":"n/a","weatherCondition":"n/a","observation":"KRNM 031753Z VRB04KT 10SM CLR 13/04 A3012 RMK AO2 SLP197 T01330044 10139 21006 50001","ICAO":"KRNM","seaLevelPressure":1019.7,"elevation":427,"countryCode":"US","lng":-116.91666666666667,"temperature":"13.3","dewPoint":"4.4","windSpeed":"04","humidity":54,"stationName":"Ramona, Ramona Airport","datetime":"2014-04-03 17:53:00","lat":33.03333333333333}}
And the formatted JSON data (more readable):
{"weatherObservation":
{
"ICAO": "KRNM",
"clouds": "n/a",
"countryCode": "US",
"datetime": "2014-04-03 17:53:00",
"dewPoint": "4.4",
"elevation": 427,
"humidity": 54,
"lat": 33.03333333333333,
"lng": -116.91666666666667,
"observation": "KRNM 031753Z VRB04KT 10SM CLR 13/04 A3012 RMK AO2 SLP197 T01330044 10139 21006 50001",
"seaLevelPressure": 1019.7,
"stationName": "Ramona, Ramona Airport",
"temperature": "13.3",
"weatherCondition": "n/a",
"windSpeed": "04"
}}
For starters I just want to display the valueForKey @"observation"
But it seems like this data is some kind of "double dictionary" how do I drill down into the "sub dictionary"?
I have no trouble handling the JSON download, I accomplish it in the viewDIdAppear method:
NSURL *weatherURL = [NSURL URLWithString:@"http://api.geonames.org/findNearByWeatherJSON?lat=33&lng=-116.87&username=InsertAPIKeyHere"];
NSData *weatherData = [NSData dataWithContentsOfURL:weatherURL];
NSError *error = nil;
NSDictionary *weatherObject = [NSJSONSerialization JSONObjectWithData:weatherData options:0 error:&error];
NSLog(@"Parsed data: %@", weatherObject);
self.weatherLabel.text =[weatherObject objectForKey:@"observation"];
This code returns nothing - I'm not actually accessing the objectForKey "observation" - it is one level down. Any ideas? I think I'm missing a simple solution here.
2 Answers
Chris Dziewa
17,781 PointsWhen you want to view a nested dictionary you should be able to link indices since an associative array is still an array. You can do something like this:
putReturnedObjectHere['weatherObservation']['observation'];
Hopefully this helps a bit.
Chris Holloway
2,427 PointsSuccess!
I nested the calls as such:
//download and create the NSDictionary
NSURL *weatherURL = [NSURL URLWithString:@"http://api.geonames.org/findNearByWeatherJSON?lat=33&lng=-116.87&username=InsertAPIKeyHere"];
NSData *weatherData = [NSData dataWithContentsOfURL:weatherURL];
NSError *error = nil;
NSDictionary *weatherObject = [NSJSONSerialization JSONObjectWithData:weatherData options:0 error:&error];
//access the nested NSDictionary with nested calls
NSString *metar = [[weatherObject valueForKey:@"weatherObservation"] valueForKey:@"observation"];
//send the NSString to a UITextLabel outlet:
self.weatherLabel.text = metar;
Your comment certainly helped. Thanks.
Chris Dziewa
17,781 PointsGlad you got it working!