title: Having trouble with NSString return type in Objective-C blocks
body: <p>Thanks guy for help you. My problem is next. I need use AFNetworking and when request petition to server, the server is response. This result I need return in my method. The method AFNetworking use block for succes or failed. I want return the return server string (operation) in succes or failed option block.</p>
  
  <pre><code>- (NSString *)executeMultipart:(NSURL *)url
  {
      __block NSString *strJSON;
  
      [_operationManager POST:[url absoluteString]parameters:_params
    constructingBodyWithBlock:^(id&lt;AFMultipartFormData&gt; formData){
          [formData appendPartWithFormData:[_params objectForKey:TAG_PHOTO] name:TAG_PHOTO];
      } success:^(AFHTTPRequestOperation *operation, id responseObject) {
          strJSON = [operation.responseString stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
          return strJSON;
      } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
          strJSON = [operation.responseString stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
          return strJSON;
      }];
  }
  </code></pre>
  
  <p>But show error: </p>
  
  <blockquote>
    <p>"Incompatible block pointer types sending 'NSString
    *(^)(AFHTTPRequestOperation *__strong, _<em>strong id)' to parameter of type 'void (^)(AFHTTPRequestOperation *</em>_strong, __strong id)'"</p>
  </blockquote>
  
  <p>I'm sorry if my problem is stupid, because I beginning develop with iOS. Please help me!!! Thanks you.</p>