objective c - Facebook iOS SDK, blank screen after authorization -

i've been following guide @ facebook's dev site. got set up, authorization seems go well, however, when accepting application , pressing "okay", thing blank screen "cancel" @ top.

i believe issue located in sessionstatechanged-method. should stop @ part (i think):

 switch (state) {     case fbsessionstateopen: {         uiviewcontroller *topviewcontroller =         [self.navcontroller topviewcontroller];         if ([[topviewcontroller modalviewcontroller]              iskindofclass:[myloginviewcontroller class]]) {             [topviewcontroller dismissmodalviewcontrolleranimated:yes];         }     }   break; 

so, if logging in , authorization success, should happen, right? well, according breakpoints, never happens. maybe that´s why may application never gets opened again?

anyway, i'm thankful tips or advice can on one.

edit: i've discovered problem opensession-method:

    - (void)opensession {     [fbsession openactivesessionwithreadpermissions:nil                                        allowloginui:yes                                   completionhandler:      ^(fbsession *session,        fbsessionstate state, nserror *error) {          [self sessionstatechanged:session state:state error:error];//this never gets called!!!      }]; } 

the sessionstatechanged-method never gets called, have no idea why.

your application never opened because didn't create url schemes redirect back. see screenshot fb documentation.