objective c - NSURLSession uploadTaskWithRequest - use block within completion handler -

i have class manages calls api. has method manage this, lets call callapimethod:

this method accepts success , fail block.

inside method, call uploadtaskwithrequest make call api. within uploadtaskwithrequest completion handler i'd (depending on result) pass results through either success or fail blocks.

i'm having issues this. works , keeping super tidy when call callapimethod using success/fail blocks it's locking ui/mainthread rather being asynchronous i'd expect.

how should go implementing pattern? or there better way go it?

i don't need support pre-ios7.

thanks

edit: basic implementation discussed above.

- (void)callapimethod:(nsstring *)method withdata:(nsstring *)requestdata as:(krequesttype)requesttype success:(void (^)(id responsedata))success failure:(void (^)(nsstring *errordescription))failure {     [redacted]     nsurlsession *session = [nsurlsession sharedsession];     nsurlsessiondatatask *task = [session uploadtaskwithrequest:request                                                        fromdata:postdata                                               completionhandler:                                   ^(nsdata *data, nsurlresponse *response, nserror *error) {                                       if (error) {                                           failure(error.description);                                       } else {                                           nserror *jsonerror;                                           id responsedata = [nsjsonserialization                                                              jsonobjectwithdata:data                                                              options:kniloptions                                                              error:&jsonerror];                                           if (jsonerror) {                                               failure(jsonerror.description);                                           } else {                                               success(responsedata);                                           }                                       }                                   }];      [task resume]; } 

callapi method, used follows (from uitableviewcontroller):

[apicontroller callapimethod:@"users.json?action=token"                     withdata:logindata                           as:krequestpost                      success:^(id responsedata) {                          if ([responsedata iskindofclass:[nsdictionary class]]) {                              if ([responsedata objectforkey:@"token"]) {                                  //store token/credentials                              } else if ([responsedata objectforkey:@"error"]) {                                  //error                                  [self displayerrormessage:[responsedata objectforkey:@"error"]];                                  return;                              } else {                                  //undefined error                                  [self displayerrormessage:nil];                                  return;                              }                          } else {                              //error                              [self displayerrormessage:nil];                              return;                          }                           //if login success                       }                      failure:^(nsstring *errordescription) {                          [self displayerrormessage:errordescription];                      }]; 

your nsurlsession code looks fine. i'd suggest adding breakpoints can identify if deadlocking somewhere , if so, where. nothing in code sample suggest such problem.

i suggest ensure ui calls dispatched main queue. nsurlsessionuploadtask completion handler may called on background queue, ui updates (alerts, navigation, updating of uiview controls, etc.) must take place on main queue.