I created custom title view for UINavigationItem.  

And I want custom view stretch to right padding.  

What can I do??  

I tried to set rightBarButtonItem to nil.  

But it seems no solution.  

And don't stretch to left backButton area.

```
override func viewDidLoad() {
    super.viewDidLoad()

    let searchBar = CustomSearchBar()
    searchBar.autoresizingMask = .flexibleWidth
    searchBar.frame = CGRect(x: 0, y: 0, width: 400, height: 30)

    self.navigationItem.titleView = searchBar

    self.navigationItem.rightBarButtonItem = UIBarButtonItem()
}

```

See my result. I want a red area.

<https://imgur.com/a/dar3cMN>