How to send a UIView element backwards in Swift

From apple documentation:

bringSubviewToFront(_:)
sendSubviewToBack(_:)
removeFromSuperview()
insertSubview(_:atIndex:)
insertSubview(_:aboveSubview:)
insertSubview(_:belowSubview:)
exchangeSubviewAtIndex(_:withSubviewAtIndex:)

You can bring your bar to the front using:

view.bringSubviewToFront(nextBar) 

Your send your view to the back of the bar using:

nextBar.view.sendSubviewToBack(myView)

For Swift 4:

self.view.sendSubviewToBack(toBack: myView)

In Swift 4.2 it can be done with:

self.sendSubviewToBack(view: viewSentToBack)

An object in the view that is linked by an IBOutlet can be sent to back using the above function.