Asynchronous request example

Question

NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http:///];
NSURLRequest *req = [[NSURLRequest alloc]initWithURL:url];
NSURLConnection *con = [[NSURLConnection alloc]initWithRequest:req delegate:self startImmediately:YES];

In my project I used sendSynchronousRequest on NSURLConnection. It gives me crash sometimes.

So I convert this code to AsynchronousRequest. I could not find suitable code.

Somebody give me link or post code which suitable to my code. Any hep will be appreciated.

You're likely to have this question closed as being too open-ended and localized. I would suggest that you describe what you're trying to do and what you've tried and why it isn't working so that people can answer the request directly. There are lots of folks willing and able to help, but the more specific questions that indicate what you've tried and why it doesn't work tend to be the ones that get the best answers. — gaige, May 17 '13 at 11:32

score 21 · Accepted Answer · edited Sep 21 '17 at 19:49

There are couple of things you could do.

You can use sendAsynchronousRequest and handle the callback block.
You can use AFNetworking library, which handles all your requests in asynchronous fashion. Very easy to use and set up.

Code for option 1:

NSURL *url = [NSURL URLWithString:urlString];
NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url];
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:urlRequest queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
  if (error) {
    //NSLog(@"Error,%@", [error localizedDescription]);
  }
  else {
    //NSLog(@"%@", [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding]);
  }
}];

Code for option 2:

You might want to download the library & include it in your project first. Then do the following. You can follow the post on setting up here

NSURL *url = [NSURL URLWithString:@"http://httpbin.org/ip"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];

AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
    NSLog(@"IP Address: %@", [JSON valueForKeyPath:@"origin"]);
} failure:nil];

[operation start];

You can make use of NSError *error in the completionHandler block to handle any errors. — Harish, May 17 '13 at 12:03
Really helpful for me too, useful to image loading, thanks :) — Supertecnoboff, Jun 06 '15 at 10:58

score 7 · Answer 2 · answered Apr 29 '18 at 22:08

As an alternative to NSURLConnection's now deprecated sendAsynchronousRequest:queue:completionHandler: method, you could instead use NSURLSession's dataTaskWithRequest:completionHandler: method:

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.example.com"]];

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
    if (!error) {
        // Option 1 (from answer above):
        NSString *string = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
        NSLog(@"%@", string);

        // Option 2 (if getting JSON data)
        NSError *jsonError = nil;
        NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&jsonError];
        NSLog(@"%@", dictionary);
    }
    else {
        NSLog(@"Error: %@", [error localizedDescription]);
    }
}];
[task resume];

Asynchronous request example

2 Answers2

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