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

only my two cents for swift 4 / Xcode 10:

1) action has initial char changed:

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

2) add @obj:

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