Parsing JSON Object - Objective C - ios

Question

I'm struggling to see why this code is not working. I have many other views using different JSON services. All working normally. However, this one is simply not. I retrieve the values back from the service as I expect however when trying to loop over it (see below code) the Array is Nil. Clearly something simple I have missed but I have been looking at this issue far to long.
Abstract View of JSON service;
{
"0": {
"altitude": "14500",
"latitude": "41.41555",
"longitude": "-73.09605",
"realname": "David KGNV"
},
"1": {
"altitude": "61",
"latitude": "33.67506",
"longitude": "-117.86739",
"realname": "Mark CT"
},
"10": {
"altitude": "38161",
"latitude": "40.51570",
"longitude": "-93.25554",
"realname": "Bob CYYZ"
},
"100": {
"altitude": "33953",
"latitude": "52.35600",
"longitude": "5.30384",
"realname": "Jim LIRQ"
}
}
Abstract view of the JSON call;
*Note the NSArray *currentMapArray valueKeyPath is set to "" as I need all elements within the JSON result.
NSError *_errorJson = nil;
jsonArray = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
if (_errorJson != nil) {
NSLog(#"Error %#", [_errorJson localizedDescription]);
} else {
//Do something with returned array
dispatch_async(dispatch_get_main_queue(), ^{
NSDictionary *mapJson = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
//Loop through the JSON array
NSArray *currentMapArray = [mapJson valueForKeyPath:#""];
//set up array and json call
mapArray = [[NSMutableArray alloc]init];
for (int i = 0; i< currentMapArray.count; i++)
{
//create our object
NSString *nAltitude = [[currentMapArray objectAtIndex:i] objectForKey:#"altitude"];
NSString *nRealname = [[currentMapArray objectAtIndex:i] objectForKey:#"realname"];
NSString *nLatitude = [[currentMapArray objectAtIndex:i] objectForKey:#"latitude"];
NSString *nLongitude = [[currentMapArray objectAtIndex:i] objectForKey:#"longitude"];
[mapArray addObject:[[LiveVatsimMap alloc]initWithaltitude:nAltitude andrealname:nRealname andlatitude:nLatitude andlongitude:nLongitude]];
}
The results of currentMapArray is NIL resulting the NSString not being filled out appropriately.
for (int i = 0; i< currentMapArray.count; i++)
Of course when I hard code the value of JSON node i.e. 10 into the ValueKeyPath then it provides the correct data results and populates accordingly.
Any ideas? Be nice...I'm only new at this objective c stuff.

Answer 1

Your JSON doesn't have an array - it is a dictionary of dictionaries.
You can iterate over it using
NSArray *keys=[jsonArray allKeys];
for (NSString *key in keys) {
NSDictionary *elementDictionary=jsonArray[key];
NSString *nAltitude = elementDictionary[#"altitude"];
NSString *nRealname = elementDictionary[#"realname"];
NSString *nLatitude = elementDictionary[#"latitude"];
NSString *nLongitude = elementDictionary[#"longitude"];
[mapArray addObject:[[LiveVatsimMap alloc]initWithaltitude:nAltitude andrealname:nRealname andlatitude:nLatitude andlongitude:nLongitude]];
}