Getting JSON data using NSURLSession

Question

Im trying to get Data from google distance api using NSURLSession but as seen below in code when i print response and data, i get the results as NULL. What can be the issue? or is there any other better way of fetching JSON data.

NSString *urlAsString = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/distancematrix/json?origins=Vancouver+BC|Seattle&destinations=San+Francisco|Victoria+BC&mode=bicycling&language=fr-FR&key=API-KEY"];

NSURL *url = [NSURL URLWithString:urlAsString];


NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];

[[session dataTaskWithURL:[NSURL URLWithString:urlAsString]
            completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

                NSLog(@"RESPONSE: %@",response);
                NSLog(@"DATA: %@",data);


            }] resume];

You may want to edit out your api key to protect yourself from service abuse. — Desdenova, Feb 23 '16 at 15:02
You don't need that standalone "`NSURL *url =`" line up there. You don't use it. — Michael Dautermann, Feb 23 '16 at 15:05

Niko · Accepted Answer · 2016-02-23T15:17:31.290

You should use stringByAddingPercentEscapesUsingEncoding: on your url string, this is why you didn't get a response : the server returned an error.

You should have checked the error ;)

I replaced your API key in URL string, remember to put your own if you copy/paste my code :)

NSString *urlAsString = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/distancematrix/json?origins=Vancouver+BC|Seattle&destinations=San+Francisco|Victoria+BC&mode=bicycling&language=fr-FR&key=YOUR-API-KEY"];

NSCharacterSet *set = [NSCharacterSet URLQueryAllowedCharacterSet];
NSString *encodedUrlAsString = [urlAsString stringByAddingPercentEncodingWithAllowedCharacters:set];

NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];

[[session dataTaskWithURL:[NSURL URLWithString:encodedUrlAsString]
        completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

    NSLog(@"RESPONSE: %@",response);
    NSLog(@"DATA: %@",data);

    if (!error) {
        // Success
        if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
            NSError *jsonError;
            NSDictionary *jsonResponse = [NSJSONSerialization JSONObjectWithData:data options:0 error:&jsonError];

            if (jsonError) {
                // Error Parsing JSON

            } else {
                // Success Parsing JSON
                // Log NSDictionary response:
                NSLog(@"%@",jsonResponse);
            }
        }  else {
            //Web server is returning an error
        }
    } else {
        // Fail
        NSLog(@"error : %@", error.description);
    }
}] resume];

thanks! encoding has worked..but the way you have encoded is deprecated iOS 9 onwards. — Mukul More, Feb 23 '16 at 15:17

score 3 · Answer 2 · edited May 23 '17 at 11:54

3

You might get a really good hint if you print out what's returned in the error parameter.

I.E.:

NSString *unencodedURLString = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/distancematrix/json?origins=Vancouver+BC|Seattle&destinations=San+Francisco|Victoria+BC&mode=bicycling&language=fr-FR&key=API-KEY"];
NSString *encodedURLString = (NSString *)CFURLCreateStringByAddingPercentEscapes(
                        NULL,
                        (CFStringRef)unencodedURLString,
                        NULL,
                        (CFStringRef)@"!*'();:@&=+$,/?%#[]",
                        kCFStringEncodingUTF8 );

[[session dataTaskWithURL:[NSURL URLWithString:encodedURLString]
            completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

    if (error != nil)
    {
       // if there's an error, print it out...
       NSLog(@"error in NSURLSession is %@", [error localizedDescription]);
    } else {
       NSLog(@"RESPONSE: %@",response);
       NSLog(@"DATA: %@",data);
    }
}] resume];

The URL encoding routine I'm using is found here.

edited May 23 '17 at 11:54

Community

1
1

answered Feb 23 '16 at 14:50

Michael Dautermann

88,797
17
166
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its says unsupported URL.but if i run the same url on browser i see the json data. – Mukul More Feb 23 '16 at 14:52
@Rusty well, there you have it. – njzk2 Feb 23 '16 at 14:54
@njzk2 i didn't understand. – Mukul More Feb 23 '16 at 14:54
yeah i understood that ..but if the url is giving me json in browser it means that my url is correct. @njzk2 what can be the issue with the format any idea? – Mukul More Feb 23 '16 at 14:56
It probably has to do with URL encoding your parameters – njzk2 Feb 23 '16 at 14:56

score 0 · Answer 3 · answered Feb 23 '16 at 14:57

0

From the Documentation:

The url must be in the format:

https://maps.googleapis.com/maps/api/distancematrix/json?origins=Vancouver+BC|Seattle&destinations=San+Francisco|Victoria+BC&key=YOUR_API_KEY

You are requesting:

origins: Vancouver+BC|Seattle
destinations: San+Francisco|Victoria+BC
mode: driving
key: API_KEY

For Transit:

https://maps.googleapis.com/maps/api/distancematrix/json?origins=Vancouver+BC|Seattle&destinations=San+Francisco|Victoria+BC&mode=transit&transit_mode=train&key=YOUR_API_KEY

You are requesitn:

  origins: Vancouver+BC|Seattle
destinations: San+Francisco|Victoria+BC
mode: transit
transit_mode: train
key: API_KEY

answered Feb 23 '16 at 14:57

Teja Nandamuri

11,045
6
57
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i have the same url ..still it says unsupported url – Mukul More Feb 23 '16 at 15:00
try removing the language tag you have in your url – Teja Nandamuri Feb 23 '16 at 15:00
im not sure if API key have dashes in it. Also check if your api key is correct or not. – Teja Nandamuri Feb 23 '16 at 15:01
did you check the link in the POSTMan plugin in chrome ? See if you get any json data in there – Teja Nandamuri Feb 23 '16 at 15:07
How can we pass longitude and latitude in Google Distance Matrix API request ? If i have retrieved a place using Google Places how to pass the place to Google Distance Matrix API? @Mr.T – Mukul More Feb 23 '16 at 15:42
there is parameter called origins, and you can send coordinates like: origins=Bobcaygeon+ON|41.43206,-81.38992 – Teja Nandamuri Feb 23 '16 at 15:47

Getting JSON data using NSURLSession

3 Answers3