How to clear content on a collection view layout ios

I am developing a iOS app in which i am using a customized collection view. in the menu bar it has list of 3 controller 1, 2, 3. when i select 2 i want to create a new collection view layout and clear the previous one . Is it possible to clear data from previous collection view layout. Collection view is being created programmatically iOS.

This is my piece of code.

• 
  

  (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{

  
  

  NSLog(@"indexpath : %ld",(long)indexPath.row);

  
  

  if(((long)indexPath.row==0) && (indexPath.section==0)){ HelpController *three=[[HelpController alloc] initWithNibName:@"HelpController" bundle:nil]; [ self presentViewController:three animated:YES completion:nil]; // [self.navigationController pushViewController:three animated:YES]; NSLog(@"Help");

  
  

  } if(((long)indexPath.row==1) && (indexPath.section==0)){

  
  

  
      backupController *bckup=[[backupController alloc]initWithNibName:@"backupController" bundle:nil];
      [self presentViewController:bckup animated:YES completion:nil];
     // [self.navigationController pushViewController:bckup animated:YES];
      NSLog(@"BackUp");
  
  

  
  

  } if(((long)indexPath.row==2) && (indexPath.section==0)){ NSLog(@"Children"); [self.navigationController dismissViewControllerAnimated:YES completion:nil];

  
  

  } if(((long)indexPath.row==3) && (indexPath.section==0)){ AboutusController *three=[[AboutusController alloc] initWithNibName:@"AboutusController" bundle:nil]; [ self presentViewController:three animated:YES completion:nil]; NSLog(@"AboutUS");

  
  

  } if(((long)indexPath.row==4) && (indexPath.section==1)){ AddChildViewController *three=[[AddChildViewController alloc] initWithNibName:@"AddChildViewController" bundle:nil]; [ self.navigationController pushViewController:three animated:YES]; NSLog(@"AboutUS");

  
  

  } if(((long)indexPath.row==0) && (indexPath.section==1)){

  
  

  
  NSString *savedValue = [[NSUserDefaults standardUserDefaults]
                          stringForKey:@"firstchild"];
  [[NSUserDefaults standardUserDefaults] setObject:savedValue forKey:@"childname"];
  
  [[childDBHelper sharedInstance] createDatabase];
  
  AddChildViewController *add =[[AddChildViewController alloc]initWithNibName:@"AddChildViewController" bundle:nil];
  [add navigatenext];
  //  [self.navigationController popToRootViewControllerAnimated:];
  [self viewWillAppear:YES];
  [self viewDidLoad];
  
  

  
  

  } if(((long)indexPath.row==1) && (indexPath.section==1)){

  
  

  
  NSString *savedValue = [[NSUserDefaults standardUserDefaults]
                          stringForKey:@"secondchild"];
  [[NSUserDefaults standardUserDefaults] setObject:savedValue forKey:@"childname"];
  
  [[childDBHelper sharedInstance] createDatabase];
  
  AddChildViewController *add =[[AddChildViewController alloc]initWithNibName:@"AddChildViewController" bundle:nil];
   [add navigatenext];
  
  

  
  

  // [self.navigationController popToRootViewControllerAnimated:]; [self viewWillAppear:YES]; [self viewDidLoad]; } if(((long)indexPath.row==2) && (indexPath.section==1)){

  
  

  
  NSString *savedValue = [[NSUserDefaults standardUserDefaults]
                          stringForKey:@"thirdchild"];
  [[NSUserDefaults standardUserDefaults] setObject:savedValue forKey:@"childname"];
  
  [[childDBHelper sharedInstance] createDatabase];
  
  AddChildViewController *add =[[AddChildViewController alloc]initWithNibName:@"AddChildViewController" bundle:nil];
  [add navigatenext];
  //  [self.navigationController popToRootViewControllerAnimated:];
  [self viewWillAppear:YES];
  [self viewDidLoad];
  
  

  
  

  } if(((long)indexPath.row==3) && (indexPath.section==1)){

  
  

  
  NSString *savedValue = [[NSUserDefaults standardUserDefaults]
                          stringForKey:@"fourthchild"];
  [[NSUserDefaults standardUserDefaults] setObject:savedValue forKey:@"childname"];
  
  [[childDBHelper sharedInstance] createDatabase];
  
  AddChildViewController *add =[[AddChildViewController alloc]initWithNibName:@"AddChildViewController" bundle:nil];
  [add navigatenext];
  //  [self.navigationController popToRootViewControllerAnimated:];
  [self viewWillAppear:YES];
  [self viewDidLoad];
  
  

  
  

  }

  
  

}

even after selecting index path 2 in section tableview section one my menu bar does not hide and the previous collection view data still exist in layout .