Getting data out of the NSURLResponse completion block

Question

It looks like I didn\'t get the concept of blocks completely yet...

In my code I have to get out the JSON data from the asychronous block to be retur

Answer 1

First, to answer your question:

But for some reason returned json object is nil. I wonder why?

The variable that you are returning has not been set at the time when you return it. You cannot harvest the results immediately after the sendAsynchronousRequest:queue:completionHandler: method has returned: the call has to finish the roundtrip before calling back your block and setting json variable.

Now a quick note on what to do about it: your method is attempting to convert an asynchronous call into a synchronous one. Try to keep it asynchronous if you can. Rather than expecting a method that returns a NSMutableDictionary*, make a method that takes a block of its own, and pass the dictionary to that block when the sendAsynchronousRequest: method completes:

- (void)executeRequestUrlString:(NSString *)urlString withBlock:(void (^)(NSDictionary *jsonData))block {
    // Prepare for the call
    ...
    // Make the call
    [NSURLConnection sendAsynchronousRequest:request
                                    queue:[NSOperationQueue currentQueue]
                        completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
        NSLog(@"dataAsString %@", [NSString stringWithUTF8String:[data bytes]]);
        NSError *error1;
        NSMutableDictionary * innerJson = [NSJSONSerialization
            JSONObjectWithData:data options:kNilOptions error:&error1
        ];
        block(innerJson); // Call back the block passed into your method
        }];

}