ios - UIPageViewController crash without stack log -

trying implement uipageviewcontroller. starting off adding single uiviewcontroller page. app crashes without stack log. i'm not facing exception i've enabled exception breakpoints. similar question asked here. doesn't seem solving problem.

this i'm doing:

- (void)viewdidload {     [super viewdidload];      self.datasource = self;     self.delegate = self;      // 3 vcs     self.view.backgroundcolor = [uicolor clearcolor];      self.matchinfovc = [[matchinfoviewcontroller alloc] initwithnibname:@"matchinfoviewcontroller" bundle:nil];     self.matchinfovc.index = 1;      uiviewcontroller *initialviewcontroller = (uiviewcontroller*)[self viewcontrolleratindex:0];      nsarray *viewcontrollers = [nsarray arraywithobject:initialviewcontroller];      [self setviewcontrollers:viewcontrollers direction:uipageviewcontrollernavigationdirectionforward animated:no completion:nil]; }  #pragma mark uipageviewcontroller delegates - (uiviewcontroller *)pageviewcontroller:(uipageviewcontroller *)pageviewcontroller viewcontrollerbeforeviewcontroller:(uiviewcontroller *)viewcontroller {      nsuinteger index = [(matchinfoviewcontroller *)viewcontroller index];     if (index == 0) {         return nil;     }     index--;      return [self viewcontrolleratindex:index]; }  - (uiviewcontroller *)pageviewcontroller:(uipageviewcontroller *)pageviewcontroller viewcontrollerafterviewcontroller:(uiviewcontroller *)viewcontroller {      nsuinteger index = [(matchinfoviewcontroller *)viewcontroller index];     index++;      if (index == 2) {         return nil;     }     return [self viewcontrolleratindex:index];  }  - (uiviewcontroller *)viewcontrolleratindex:(nsuinteger)index {     switch (index) {         case 0:{              self.matchinfovc.index = index;             return self.matchinfovc;             break;         }     }     return nil; }