How to add custom view on right of navigation bar Swift?

Question

I am trying to add a custom view on right of UINavigationBar. What I tried is the following, but the view is not showing up! Please help, thanks in advance!

let viewOnrightButton = UIView(frame: CGRect(x: 2, y: 2, width: 60, height: 22))
 // viewOnrightButton.frame = CGRectMake(2, 2, 60, 22)
viewOnrightButton.layer.cornerRadius = 2
viewOnrightButton.backgroundColor = UIColor(red: 0.961, green: 0.827, blue: 0.239, alpha: 1.00)

lblNumbersOfBanana.frame = CGRectMake(2, 1, viewOnrightButton.frame.width-20, 20)
lblNumbersOfBanana.text = "001"

var bananaImgView = UIImageView(frame: CGRect(x: viewOnrightButton.frame.width-22, y: 0, width: 20, height: 20))
 //  bananaImgView.frame = CGRectMake(viewOnrightButton.frame.width-22, 0, 20, 20)
bananaImgView.image = UIImage(named: "banana")

viewOnrightButton.addSubview(lblNumbersOfBanana)
viewOnrightButton.addSubview(bananaImgView)

self.navigationItem.rightBarButtonItem?.customView = viewOnrightButton

Answer 1

// creating uiview and add three custom buttons

 func addRightButton(){

    let viewFN = UIView(frame: CGRectMake(0, 0, 180,40))
        viewFN.backgroundColor = UIColor.yellowColor()
    let button1 = UIButton(frame: CGRectMake(0,8, 40, 20))
    button1.setImage(UIImage(named: "notification"), forState: UIControlState.Normal)
    button1.setTitle("one", forState: .Normal)

    button1.addTarget(self, action: #selector(self.didTapOnRightButton), forControlEvents: UIControlEvents.TouchUpInside)

    let button2 = UIButton(frame: CGRectMake(40, 8, 60, 20))
    button2.setImage(UIImage(named: "notification"), forState: UIControlState.Normal)
    button2.setTitle("tow", forState: .Normal)
    let button3 = UIButton(frame: CGRectMake(80, 8, 60, 20))
     button3.setImage(UIImage(named: "notification"), forState: UIControlState.Normal)
    button3.setTitle("three", forState: .Normal)

    button3.addTarget(self, action: #selector(self.didTapOnRightButton), forControlEvents: UIControlEvents.TouchUpInside)

    viewFN.addSubview(button1)
    viewFN.addSubview(button2)
    viewFN.addSubview(button3)


    let rightBarButton = UIBarButtonItem(customView: viewFN)
    self.navigationItem.rightBarButtonItem = rightBarButton

}