JSON – Andri Yadi

If you’re like me, a long time .NET developer that finally also became iOS Developer, most likely you’ll use .NET to create server-side API/backend to serve iOS apps. If yes, you may use OData or WCF Data Services to implement such backend. Long before ASP.NET Web API came along, OData is the easiest way to create API.

OData can output JSON, even though it outputs in XML by default. As we know, we simply add/change “Accept” header in our HTTP request to “application/json” to get JSON responses. iOS SDK has built-in JSON parsing support since iOS 5 by using NSJSONSerialization class. All seems a perfect combination, while occasionally it’s not.

Continue reading OData and NSJSONSerialization

Let’s say I want to get tweets from Twitter.

I send HTTP request to Twitter with “Accept” header set to “application/json”
Receive returned JSON and parse it
Do whatever I want with parsed JSON

//The URL of JSON service
NSString *_urlString = @"http://twitter.com/status/user_timeline/andri_yadi?count=50";
NSURL *_url = [NSURL URLWithString:_urlString];

NSMutableURLRequest *_request = [NSMutableURLRequest requestWithURL:_url];

NSDictionary *_headers = [NSDictionary dictionaryWithObjectsAndKeys:@"application/json", @"accept", nil];

[_request setAllHTTPHeaderFields:_headers];

[NSURLConnection sendAsynchronousRequest:_request
                                       queue:[NSOperationQueue mainQueue]
                           completionHandler:^(NSURLResponse* response, NSData* data, NSError* error) {

                               NSError *_errorJson = nil;
                               NSArray *_tweetArr = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&_errorJson];

                               if (_errorJson != nil) {
                                   NSLog(@"Error %@", [_errorJson localizedDescription]);
                               } else {
                                   //Do something with returned array
                                   dispatch_async(dispatch_get_main_queue(), ^{

                                       [self didLoadedTweetsWithResult:_tweetArr];
                                   });                                   
                               }

 }];

//The URL of JSON service

NSString *_urlString = @"http://twitter.com/status/user_timeline/andri_yadi?count=50";

NSURL *_url = [NSURL URLWithString:_urlString];

NSMutableURLRequest *_request = [NSMutableURLRequest requestWithURL:_url];

NSDictionary *_headers = [NSDictionary dictionaryWithObjectsAndKeys:@"application/json", @"accept", nil];

[_request setAllHTTPHeaderFields:_headers];

[NSURLConnection sendAsynchronousRequest:_request

queue:[NSOperationQueue mainQueue]

completionHandler:^(NSURLResponse* response, NSData* data, NSError* error) {

NSError *_errorJson = nil;

NSArray *_tweetArr = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&_errorJson];

if (_errorJson != nil) {

NSLog(@"Error %@", [_errorJson localizedDescription]);

} else {

//Do something with returned array

dispatch_async(dispatch_get_main_queue(), ^{

[self didLoadedTweetsWithResult:_tweetArr];

});

}

}];

Above code uses two API provided only in iOS 5 or later:

Asynchronous and block-based handler NSURLConnection
NSJSONSerialization

You don’t need any third party libraries.

Tag: JSON

OData and NSJSONSerialization

Consuming and Parsing JSON Service in iOS 5 – The Easy Way