How to parse JSON response with nested dictionary and dynamic keys in objective-c?

Question

How do I parse JSON response that has nested dictionary and dynamic keys ?

response dictionary: {
"Meta Data" =     {
    "1. Information" = "Intraday Prices and Volumes for Digital Currency";
    "2. Digital Currency Code" = BTC;
    "3. Digital Currency Name" = Bitcoin;
    "4. Market Code" = USD;
    "5. Market Name" = "United States Dollar";
    "6. Interval" = 5min;
    "7. Last Refreshed" = "2018-08-07 15:45:00";
    "8. Time Zone" = UTC;
};
"Time Series (Digital Currency Intraday)" =     {
    "2018-08-06 01:20:00" =         {
        "1a. price (USD)" = "7074.26229231";
        "1b. price (USD)" = "7074.26229231";
        "2. volume" = "66564.61550730";
        "3. market cap (USD)" = "470895549.48574001";
    };

I am trying to show the latest BitCoin price in my app. JSON response will have time interval as dynamic keys, such as “2018-08-06 01:20:00”.
I am only interested in “1a. price (USD)” = “7074.26229231” part of each interval. How can I get that value considering the fact that outer keys will be dynamic? (every 5 minutes there will be a new key value pair for that interval)

Code I have written so far:

NSString *urlString = @"https://www.alphavantage.co/query?function=DIGITAL_CURRENCY_INTRADAY&symbol=BTC&market=USD&apikey=*******";

NSURL *url = [NSURL URLWithString:urlString];

[[NSURLSession.sharedSession dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
    NSError *err;
    NSDictionary *coinDictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&err];
    if (err) {
        NSLog(@"Failed to serialize into JSON: %@", err);
        return;
    }

    NSLog(@"response dictionary: %@", coinDictionary);

}] resume];

full JSON response: demo

Answer 1

This prints the date key and the value for 1a price of each dictionary

NSDictionary *coinDictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&err];
NSDictionary *timeSeries = coinDictionary[@"Time Series (Digital Currency Intraday)"];
for (NSString *key in timeSeries) {
    NSDictionary *rates = timeSeries[key];
    NSString *price1a = rates[@"1a. price (EUR)"];
    NSLog(@"%@ - %@", key, price1a);
}

To get only the most recent date get the dictionary keys which represent the dates, sort them and get the last one.

NSDictionary *coinDictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&err];
NSDictionary *timeSeries = coinDictionary[@"Time Series (Digital Currency Intraday)"];
NSArray *keys = [[timeSeries allKeys] sortedArrayUsingSelector:@selector(compare:)];
NSString *mostRecentDate = keys.lastObject;
NSDictionary *rates = timeSeries[mostRecentDate];
NSString *price1a = rates[@"1a. price (EUR)"];