ios - Setting an image after retreaving the result of a post request takes 17s -

i making post request server returns string, says if user exist or not nickname, post notification works flawless , prints out returned result in under 1s inside completion handler, takes additional 17 20 set image based on returned result...

here code using:

- (void)textfielddidbeginediting:(uitextfield *)textfield{     // each textfield selected checkl previous text field formating      if (textfield == registeremailaddresstextfield)     {          //check if nickname @ least 6 charactes          if (registernicknametextfield.text.length < 6) {             nslog(@"emial text field");             [registernicknamecheckmarklabel setimage:[uiimage imagenamed:@"wrong_checkmark.png"]];          }else{             nslog(@"checking nickname");             //check if nickname exists or not              nsurl *url = [nsurl urlwithstring:@"myurl"];               //create session custom configuration             nsurlsessionconfiguration *sessionconfiguration = [nsurlsessionconfiguration defaultsessionconfiguration];              nsurlsession *session = [nsurlsession sessionwithconfiguration:sessionconfiguration];               nsmutableurlrequest *request = [[nsmutableurlrequest alloc] initwithurl:url];             request.httpmethod = @"post";                nserror *error = nil;             nsstring* str = [nsstring stringwithformat:@"username=%@", registernicknametextfield.text];             nsdata* jsondata = [str datausingencoding:nsutf8stringencoding];              [request setvalue:[nsstring stringwithformat:@"%d", (int)registernicknametextfield.text.length] forhttpheaderfield:@"content-length"];             if (!error) {                  nsurlsessionuploadtask *uploadtask = [session uploadtaskwithrequest:request                                                                            fromdata:jsondata completionhandler:^(nsdata *data,nsurlresponse *response,nserror *error) {                                                                                  nsstring *responsestring = [[nsstring alloc] initwithdata:data encoding:nsutf8stringencoding];                                                                                nsstring* result2 = [responsestring stringbytrimmingcharactersinset:[nscharacterset whitespaceandnewlinecharacterset]];                                                                                nsstring *secondstring = [result2 stringbyreplacingoccurrencesofstring:@" " withstring:@""];                                                                                if ([secondstring isequaltostring:@"exist"]) {                                                                                    nslog(@"nickname allready exists");                                                                                    [registernicknamecheckmarklabel setimage:[uiimage imagenamed:@"wrong_checkmark.png"]];                                                                                }else{                                                                                    [registernicknamecheckmarklabel setimage:[uiimage imagenamed:@"correct_checkmark.png"]];                                                                                    nslog(@"nickname doesn't exists");                                                                                }                                                                            }];                   [uploadtask resume];             }          }         } } 

i tried no success force refresh screen using these code:

dispatch_time_t poptime = dispatch_time(dispatch_time_now,                                         (int64_t)(0.005 * nsec_per_sec)); dispatch_after(poptime, dispatch_get_main_queue(), ^(void) {     [self.view setneedsdisplay]; }); 

so suggested @dan putted on main queue:

dispatch_async(dispatch_get_main_queue(), ^{                                                                                                      if ([secondstring isequaltostring:@"exist"]) {                                                                                                [registernicknamecheckmarklabel setimage:[uiimage  imagenamed:@"wrong_checkmark.png"]];                                                                                            }else{                                                                                                [registernicknamecheckmarklabel setimage:[uiimage  imagenamed:@"correct_checkmark.png"]];                                                                                            }                                                                         });