How do I create a standard iOS Share button?

Question

The iOS Human Interface Guidelines say:

Use the system-provided Share button. Users are familiar with the meaning and behavior of thi

Answer 1

Here is the code for Swift 3.

func addShareBarButtonItem() {

    let shareButton = UIBarButtonItem(barButtonSystemItem: .Action, target: self, action: #selector(MyViewController.shareButtonPressed))

    self.navigationItem.rightBarButtonItem = shareButton
}

func shareButtonPressed() {
    //Do something now!
}