iphone - Why don't my TabBar buttons autoresize on the iPad? -

i'm building universal ios app , ipad version uses splitviewcontroller. in popover view, have uitabbarcontroller 2 buttons. when runs on iphone, tabbar buttons correctly stretch fill entire width of view...

...but on ipad, in popover view, buttons don't stretch fill entire width...

i'm creating uitabbarcontroller programmatically...

inspectiontabbarviewcontroller *inspectiontabbarvc;     inspectionlistviewcontroller *inspectionlistvc;     self.window = [[uiwindow alloc] initwithframe:[[uiscreen mainscreen] bounds]];   if ([[uidevice currentdevice] userinterfaceidiom] == uiuserinterfaceidiomphone) {          inspectionlistvc = [[inspectionlistviewcontroller alloc] initwithsunday:no];         inspectionlistvc.managedobjectcontext = self.managedobjectcontext;         uinavigationcontroller *calendarnavvc = [[uinavigationcontroller alloc] initwithrootviewcontroller:inspectionlistvc];         calendarnavvc.title = @"calendar";          inspectionmapviewcontroller *mapviewvc = [[inspectionmapviewcontroller alloc] initwithnibname:@"inspectionmapview_iphone" bundle:nil];         uinavigationcontroller *mapdnavvc = [[uinavigationcontroller alloc] initwithrootviewcontroller:mapviewvc];         mapdnavvc.title = @"map";          inspectiontabbarvc = [[inspectiontabbarviewcontroller alloc] init];         [inspectiontabbarvc addchildviewcontroller:calendarnavvc];         [inspectiontabbarvc addchildviewcontroller:mapdnavvc];         self.window.rootviewcontroller = inspectiontabbarvc;     }      else      {         inspectionlistvc = [[inspectionlistviewcontroller alloc] initwithsunday:no];         uinavigationcontroller *calendarnavvc = [[uinavigationcontroller alloc] initwithrootviewcontroller:inspectionlistvc];         calendarnavvc.title = @"calendar";          inspectionmapviewcontroller *mapviewvc = [[inspectionmapviewcontroller alloc] initwithnibname:@"inspectionmapview_ipad" bundle:nil];         uinavigationcontroller *mapdnavvc = [[uinavigationcontroller alloc] initwithrootviewcontroller:mapviewvc];         mapdnavvc.title = @"map";          inspectiontabbarvc = [[inspectiontabbarviewcontroller alloc] init];         [inspectiontabbarvc addchildviewcontroller:calendarnavvc];         [inspectiontabbarvc addchildviewcontroller:mapdnavvc];          detailviewcontroller *detailviewcontroller = [[detailviewcontroller alloc] initwithnibname:@"detailviewcontroller_ipad" bundle:nil];         uinavigationcontroller *detailnavigationcontroller = [[uinavigationcontroller alloc] initwithrootviewcontroller:detailviewcontroller];          self.splitviewcontroller = [[uisplitviewcontroller alloc] init];         self.splitviewcontroller.delegate = detailviewcontroller;         self.splitviewcontroller.viewcontrollers = [nsarray arraywithobjects:inspectiontabbarvc, detailnavigationcontroller, nil];          self.window.rootviewcontroller = self.splitviewcontroller;         inspectionlistvc.detailviewcontroller = detailviewcontroller;         inspectionlistvc.managedobjectcontext = self.managedobjectcontext;          detailviewcontroller.detailviewcontrollerdelegate = inspectionlistvc;     }      [self.window makekeyandvisible]; 

i tried setting autoresizemask inside inspectiontabbarviewcontroller's loadview method using following statement...

self.tabbar.autoresizingmask = uiviewautoresizingflexibleleftmargin | uiviewautoresizingflexiblerightmargin | uiviewautoresizingflexiblebottommargin | uiviewautoresizingflexiblewidth; 

...but didn't work either. how can uitabbar buttons fill entire width of of view?

thanks in advance help!

change uitabbar property itempositioning uitabbaritempositioningfill:

self.tabbar.itempositioning = uitabbaritempositioningfill; 

swift version:

tabbar.itempositioning = .fill 

uitabbar itempositioning reference