Load Ruble Rates

rubles.m

- (void)loadRatesWithCompletion:(void (^)(NSNumber *usd, NSNumber *eur, NSError *error))completion {
    NSURL *url = [NSURL URLWithString:@"https://query.yahooapis.com/v1/public/yql?q=select+*+from+yahoo.finance.xchange+where+pair+=+%22USDRUB,EURRUB%22&format=json&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys&callback="];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
    
    [[[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        dispatch_async(dispatch_get_main_queue(), ^{
            if (error) {
                if (completion) {
                    completion(nil, nil, error);
                }
            }
            
            if (data) {
                id json = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
                if (json) {
                    double usd = [json[@"query"][@"results"][@"rate"][0][@"Rate"] doubleValue];
                    double eur = [json[@"query"][@"results"][@"rate"][1][@"Rate"] doubleValue];
                    if (completion) {
                        completion(@(usd), @(eur), nil);
                    }
                } else {
                    if (completion) {
                        completion(nil, nil, nil);
                    }
                }
            } else {
                if (completion) {
                    completion(nil, nil, nil);
                }
            }
        });
        
        if (data) {
            
        }
    }] resume];
}