UIBarButtonItem Support iOS 11 and higher.

[kmishukov]

I have added constraints that fix bug, when FaveButton is untouchable when it is added to navigation bar as UIBarButtonItem(customView: FaveButton), this problem occurred on iOS 11 and higher.

class ViewController: UIViewController, FaveButtonDelegate {
 
    let myButton = FaveButton(frame: CGRect(x: 0, y: 0, width: 24, height: 24),
                              faveIconNormal: UIImage(named: "star"))
    
    override func viewDidLoad() {
        super.viewDidLoad()
        myButton.delegate = self
        navigationItem.rightBarButtonItem = UIBarButtonItem(customView: myButton)
    }
    
    func faveButton(_ faveButton: FaveButton, didSelected selected: Bool) {
        print("Button pressed!")
    }
}

[joshhopkins]

Can this be merged please?