objective c - Change NSURLConnection from sendSynchronousRequest to sendAsynchronousRequest? -

my code nsurlconnection sendsynchronousrequest works fine how can change async request? tried lot nothing work.

if request empty i´ll empty array [[]] . how can catch alert message?

please ...

     [uiapplication sharedapplication].networkactivityindicatorvisible = yes;      nsstring *urlstring = @"http://www.xyz.at/sample.php";      nsurl *url = [nsurl urlwithstring:urlstring];      nsmutableurlrequest *request = [[nsmutableurlrequest alloc] init];     [request seturl:url];     [request sethttpmethod:@"post"];      nsmutabledata *body = [nsmutabledata data];      nsstring *postwerte = [nsstring stringwithformat:@"id=%@", self.textfeld.text];      [body appenddata:[postwerte datausingencoding:nsutf8stringencoding]];      [request sethttpbody:body];      nserror *error = nil;     nsdata *returndata = [nsurlconnection sendsynchronousrequest:request returningresponse:nil error:&error];     nslog(@"error: %@", error.description);      nsstring *returnstring = [[nsstring alloc] initwithdata:returndata encoding:nsutf8stringencoding];      const char *convert = [returnstring utf8string];     nsstring *responsestring = [nsstring stringwithutf8string:convert];     nsmutablearray *meinergebnis = [responsestring jsonvalue];      nsstring *cycle = @"";      nsstring *kopfdaten = [nsstring stringwithformat:@"sendungsart: %@\r\ngewicht: %@ kg\r\n\r\n", [[meinergebnis objectatindex:0] objectforkey:@"parceltypedescription"], [[meinergebnis objectatindex:0] objectforkey:@"weight"]];      cycle = [cycle stringbyappendingstring:kopfdaten];      for(int = 1; < meinergebnis.count; i++)         {          nsstring *myvalue = [nsstring stringwithformat:@"%@     plz: %@\r\nstatus: %@\r\n\r\n",                 [[meinergebnis objectatindex:i] objectforkey:@"eventtimestamp"],                 [[meinergebnis objectatindex:i] objectforkey:@"eventpostalcode"],                 [[meinergebnis objectatindex:i] objectforkey:@"parceleventreasondescription"]];          cycle = [cycle stringbyappendingstring:myvalue];          }         self.ergebnis.text = [nsstring stringwithformat:@"%@", cycle];      [uiapplication sharedapplication].networkactivityindicatorvisible = no;     [self.textfeld resignfirstresponder]; 

you could:

• create nsoperationqueue, ,

• call sendasynchronousrequest, placing of nsdata processing code inside completion block.

thus, instead of:

nsurlresponse *response = nil; nserror *error = nil; nsdata *data = [nsurlconnection sendsynchronousrequest:request returningresponse:&response error:&error];  // process resulting `data` 

use:

nsoperationqueue *queue = [[nsoperationqueue alloc] init]; [nsurlconnection sendasynchronousrequest:request queue:queue completionhandler:^(nsurlresponse *response, nsdata *data, nserror *error) {      // process resulting `data` }]; 

alternatively, implement nsurlconnectiondatadelegate methods. more information on that, see using nsurlconnection section of url loading system programming guide.

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you "if request empty": assume mean "if data returned empty". , [[]]. if that's you're getting, sounds array 1 item (which itself, empty array). or [] (which empty array)? or nil?

i'm going assume data returned [], empty array.

i'd suggest consider using nsjsonserialization, built in json parser, can use jsonvalue if want.

finally, implementation skipping first entry (nsarray uses zero-based index). i'm assuming unintentional.

nsoperationqueue *queue = [[nsoperationqueue alloc] init]; [nsurlconnection sendasynchronousrequest:request queue:queue completionhandler:^(nsurlresponse *response, nsdata *data, nserror *error) {      if (error) {         nslog(@"%s: sendasynchronousrequest error: %@", __function__, error);         return;     }      nserror *parseerror;     nsarray *meinergebnis = [nsjsonserialization jsonobjectwithdata:data options:0 error:&parseerror];      if (parseerror) {         nslog(@"%s: jsonobjectwithdata error: %@", __function__, parseerror);         return;     }      if ([meinergebnis count] == 0) {         nslog(@"%s: meinergebnis empty", __function__);         return;     }      (nsdictionary *dictionary in meinergebnis)     {         // process each dictionary entry in meinergebnis     }      // etc. }];