ios - how to show the views added in view controller -

i had created the view programatically not display on screen , gives message in console that

failed instantiate default view controller uimainstoryboardfile 'main' - perhaps designated entry point not set?

here code

  -(bool)application:(uiapplication *)application didfinishlaunchingwithoptions:(nsdictionary  *)launchoptions {      self.window = [[uiwindow alloc] initwithframe:[[uiscreen mainscreen] bounds]] ;      exmtableviewcontroller *vc =[[exmtableviewcontroller alloc] init];      self.window.rootviewcontroller=vc;      self.window.backgroundcolor =[uicolor whitecolor];      [self.window makekeyandvisible];      return yes; } 

*code in viewdidload *

- (void)viewdidload {     [super viewdidload];      uiimageview *img =[[uiimageview alloc] initwithframe:cgrectmake(10, 10, 100, 20)];      self.imageview=img;      [self.view addsubview:self.imageview];      uilabel *lbl =[[uilabel alloc] initwithframe:cgrectmake(10, 10, 100, 20)];      lbl.text =@"hello";      self.view =lbl;   } 

instead line self.view =lbl;, use [self.view addsubview:lbl]; add subview view.