Parsing a JSON array with dictionaries - ios

Question

I'm having some trouble getting to the data I want to in the JSON file. Here is a shortened version of the output from my console:
{
AUD = {
15m = "125.15547";
24h = "124.74";
buy = "121.0177";
last = "125.15547";
sell = "123.44883";
symbol = "$";
};
BRL = {
15m = "120.34";
24h = "120.34";
buy = "120.34";
last = "120.34";
sell = "120.34";
symbol = "R$";
};
CAD = {
15m = "129.08612";
24h = "131.07";
buy = "128.66227";
last = "129.08612";
sell = "129.08612";
symbol = "$";
};
}
I'm trying to parse the file using the built in JSON parsing library. Here is the parser in my viewDidLoad method:
_tickerArray = [NSMutableArray array];
NSURL *tickerDataURL = [NSURL URLWithString:#"https://blockchain.info/ticker"];
NSData *jsonData = [NSData dataWithContentsOfURL:tickerDataURL];
NSError *error = nil;
NSDictionary *dataDictionary = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:&error];
NSLog(#"%#", dataDictionary);
NSArray *ar = [NSArray arrayWithObject:dataDictionary];
for (NSString *key in [dataDictionary allKeys]) {
for (NSDictionary *dict in ar) {
TickerData *t;
t.currency = [dict objectForKey:key];
t.symbol = [dict objectForKey:#"symbol"];
t.last = [dict objectForKey:#"last"];
[_tickerArray addObject:t];
}
}
I want to store the currency code (like AUD or BRL) into t.currency along with some of the other data contained in the currency dictionary but now my app is crashing.
Error code:
NSInvalidArgumentException', reason: '*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil
None of the objects seem to get added to the _tickerArray
Help?
EDIT: Getting the keys to display with the proper data populating other fields:
NSDictionary *dataDictionary = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:&error];
NSLog(#"%#", dataDictionary);
for (NSString *key in [dataDictionary allKeys]) {
NSDictionary *dic=[dataDictionary objectForKey:key];
TickerData *t=[[TickerData alloc] init];
t.currency = key;//EDITED
t.symbol = [dic objectForKey:#"symbol"];
t.last = [dic objectForKey:#"last"];
[_tickerArray addObject:t];
}

Answer 1

t is nil, you have to alloc/ init it:
TickerData *t = [[TickerData alloc] init];

Answer 2

NSDictionary *dataDictionary = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:&error];
NSLog(#"%#", dataDictionary);
//NSArray *ar = [NSArray arrayWithObject:dataDictionary];//REMOVED
for (NSString *key in [dataDictionary allKeys]) {
NSDictionary *dic=[dataDictionary objectForKey:key];//ADDED
for (NSString *dickey in [dic allKeys]) { //MODIFIED
NSDictionary *dict=[dic objectForKey:dicKey];//ADDED
TickerData *t=[[TickerData alloc] init];//ALLOC INIT ?
t.currency = key;//EDITED
t.symbol = [dict objectForKey:#"symbol"];
t.last = [dict objectForKey:#"last"];
[_tickerArray addObject:t];
}
}
Your data doesn't contain any array, its all dictionaries, try the above code see comments too..
Hope it works..
Edited:
Yes you have initialize the object too, as suggested above in other answers..

Answer 3

Try it....
NSURL *url = [NSURL URLWithString:#"https://blockchain.info/ticker"];
NSLog(#"API : %#",url);
NSMutableData *jsonData = [NSMutableData dataWithContentsOfURL:url];
NSString *data = [[NSString alloc] initWithBytes: [jsonData mutableBytes] length:[jsonData length] encoding:NSUTF8StringEncoding];
dictionary = [data JSONValue];
NSDictionary *dict = [dictionary objectForKey:#"AUD"];
NSLog(#"%#",dict);
NSString *last = [dict valueForKey:#"last"];
NSLog(#"%#",last);