iOS - After logout. Login page functionality is not working in iphone/ios

- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{

	if (buttonIndex == 0)
	{
		  if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        Login_Trainer_Client *logout = [[Login_Trainer_Client alloc]initWithNibName:nil bundle:nil];
        [self.navigationController presentViewController:logout animated:NO completion:NULL];
          }else{
              Login_Trainer_Client *logout = [[Login_Trainer_Client alloc]initWithNibName:nil bundle:nil];
              [self.navigationController presentViewController:logout animated:NO completion:NULL];

          }
   
	}
	else
	{
		NSLog(@"cancel");
	}
}

- (IBAction)Logout:(id)sender
{
    
    UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:NSLocalizedString(@"Are you sure you want to log out?", nil)
                                  
                                  
                                                             delegate:self
                                                    cancelButtonTitle:NSLocalizedString(@"Cancel", nil)
                                               destructiveButtonTitle:NSLocalizedString(@"Log Out", nil)
                                                    otherButtonTitles:nil];

    actionSheet.actionSheetStyle = UIActionSheetStyleBlackTranslucent;
    [actionSheet showInView:self.view]; // show from our table view (pops up in the middle of the table)
    
    
}