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It should be possible to show and hide the section index bar in UITableView.

Possible way of calling this would be:
UITableView:hideSectionIndexBar(Bool)

In my case I want to implement the same behavior like the new iOS 8.4 Music app. When starting to scroll the section index bar should disappear until dragging finished.

Steps to Reproduce:
Create a UITableView and implement section index titles. 
Then add this code e.g. inside a UITableViewController subclass:

var showSectionIndexTitles = true

override func scrollViewWillBeginDragging(scrollView: UIScrollView) {
    showSectionIndexTitles = false
    UIView.animateWithDuration(0.5, animations: { () -> Void in
        self.tableView.reloadSectionIndexTitles()
    })
}

override func scrollViewWillBeginDecelerating(scrollView: UIScrollView) {
    showSectionIndexTitles = true
    UIView.animateWithDuration(0.5, animations: { () -> Void in
        self.tableView.reloadSectionIndexTitles()
    })
}

override func sectionIndexTitlesForTableView(tableView: UITableView) -> [AnyObject]! {
    if showSectionIndexTitles {
        return ["A", "B", "C", "D", "E"]
    } else {
        return nil
    }
}

Expected Results:
Section Index bar should move in from right edge of view when showing and when hiding it should perform the same animation in reverse, moving out of the view on the right side.