ios - Uploading photo with AFNetworking - trying understand http post and body -

i trying upload image server afnetworking. code below. server not written me not sure if code wrong or went wrong server side , im trying troubleshoot want know inside body part of request, when try log body nothing, doing wrong? when code runs end in success block server returns nothing me, , photo doesn't uploaded.

    afhttpclient *client = [[afhttpclient alloc] initwithbaseurl:baseurl];     [client registerhttpoperationclass:[afhttprequestoperation class]];      nsdictionary *params = [[nsdictionary alloc]initwithobjectsandkeys:                             title, @"title",                             desc, @"description",                             nil];      nsmutableurlrequest *request = [client multipartformrequestwithmethod:@"post" path:@"myphotoapp/upload" parameters:params constructingbodywithblock: ^(id <afmultipartformdata>formdata) {         [formdata appendpartwithfiledata:imagedata name:@"photo" filename:@"photo.png" mimetype:@"image/png"];     }];      nslog(@"request: %@", request);     nslog(@"body: %@", [[nsstring alloc] initwithdata:request.httpbody encoding:nsutf8stringencoding]);      afhttprequestoperation *operation = [[afhttprequestoperation alloc] initwithrequest:request];     [operation setcompletionblockwithsuccess:^(afhttprequestoperation *operation, id responseobject) {         nslog(@"success:%@", operation.responsestring);      } failure:^(afhttprequestoperation *operation, nserror *error) {         nslog(@"fail: %@", error.description);     }];      [operation start]; 

as side note, there online reading or book understand more how http requests made because don't quite understand it.