UITableView Grouped style in iPad

I am using UITableView to show my app开发者_JAVA百科 info but I don't why the tableview is not grouped style !! In the interface builder I change to the group style but does not change !!

![enter image description here][1]

Need to be like this :

EDITED :

- (IBAction)infoView {
    InfoViewController *showView = [[InfoViewController alloc]initWithNibName:nil bundle:nil];
    showView.modalPresentationStyle = UIModalPresentationFormSheet;
    showView.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
    [self presentModalViewController:showView animated:YES];
    [showView release]; 
}

INFOviewController is UITableView based subclass

@interface InfoViewController : UITableViewController

---

InfoViewController *showView = [[InfoViewController alloc]initWithNibName:InfoViewController bundle:nil];

Not specifying the Nib name leads to the changes made in Xib being ignored.