title: Using objective-c blocks recursively with iOS Twitter API
body: <p>So I'm trying to use the built in Twitter API in iOS 5 to retrieve a list of all the followers for a given user. In all the example documentation I can find, requests are made to the API passing inline blocks to be executed when the request returns, which is fine for most of the simpler stuff, BUT when I'm trying to get ~1000 followers, and the request is returning them paged in sizes ~100, I'm stuck on how to recursively call the request again using the 'next paging address' returned and processed inside the completion block. Here is the code:</p>
  
  <pre><code>- (void)getTwitterFollowers {
      //  First, we need to obtain the account instance for the user's Twitter account
      ACAccountStore *store = [[ACAccountStore alloc] init];
      ACAccountType *twitterAccountType = 
      [store accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
  
      //  Request access from the user for access to his Twitter accounts
      [store requestAccessToAccountsWithType:twitterAccountType 
                       withCompletionHandler:^(BOOL granted, NSError *error) {
          if (!granted) {
              // The user rejected your request 
              NSLog(@"User rejected access to his account.");
          } 
          else {
              // Grab the available accounts
              NSArray *twitterAccounts = 
              [store accountsWithAccountType:twitterAccountType];
  
              if ([twitterAccounts count] &gt; 0) {
                  // Use the first account for simplicity 
                  ACAccount *account = [twitterAccounts objectAtIndex:0];
  
                  // Now make an authenticated request to our endpoint
                  NSMutableDictionary *params = [[NSMutableDictionary alloc] init];
                  [params setObject:@"1" forKey:@"include_entities"];
  
                  //  The endpoint that we wish to call
                  NSURL *url = [NSURL URLWithString:@"http://api.twitter.com/1/followers.json"];
  
                  //  Build the request with our parameter 
                  request = [[TWRequest alloc] initWithURL:url 
                                             parameters:params 
                                          requestMethod:TWRequestMethodGET];
  
                  [params release];
  
                  // Attach the account object to this request
                  [request setAccount:account];
  
                  [request performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {
                      if (!responseData) {
                          // inspect the contents of error 
                          FullLog(@"%@", error);
                      } 
                      else {
                          NSError *jsonError;
                          followers = [NSJSONSerialization JSONObjectWithData:responseData 
                                                                    options:NSJSONReadingMutableLeaves 
                                                                      error:&amp;jsonError];            
                          if (followers != nil) {                          
                              // THE DATA RETURNED HERE CONTAINS THE NEXT PAGE VALUE NEEDED TO REQUEST THE NEXT 100 FOLLOWERS, 
                              //WHAT IS THE BEST WAY TO USE THIS??
                              FullLog(@"%@", followers);
                          } 
                          else { 
                              // inspect the contents of jsonError
                              FullLog(@"%@", jsonError);
                          }
                      }
                  }];         
              } // if ([twitterAccounts count] &gt; 0)
          } // if (granted) 
      }];
      [store release];
  }
  </code></pre>
  
  <p>Ideally I'd like some way to listen for this data being returned, check for a next page value and if it exists, reuse the code block and append the data returned. I', sure there must be a 'best-practice' way to achieve this, any help would be much appreciated!  </p>