Change size of UIBarButtonItem (image) in Swift 3

Question

I am trying to change the size of some icons in my navBar, but I am a little confused as to how to do this? My code so far is:

func setUpNavBarButtons() {
          


        

Answer 1

This is how I did it

iOS 10 and below

func setUpMenuButton(){
    let menuBtn = UIButton(type: .custom)
    menuBtn.frame = CGRect(x: 0.0, y: 0.0, width: 20, height: 20)
    menuBtn.setImage(UIImage(named:"menuIcon"), for: .normal)
    menuBtn.addTarget(self, action: #selector(vc.onMenuButtonPressed(_:)), for: UIControlEvents.touchUpInside)

    let menuBarItem = UIBarButtonItem(customView: menuBtn)
    self.navigationItem.leftBarButtonItem = menuBarItem
}

iOS 11 - Navigation bar come up with Autolayout so frame setting may not work

func setUpMenuButton(){
    let menuBtn = UIButton(type: .custom)
    menuBtn.frame = CGRect(x: 0.0, y: 0.0, width: 20, height: 20)
    menuBtn.setImage(UIImage(named:"menuIcon"), for: .normal)
    menuBtn.addTarget(self, action: #selector(vc.onMenuButtonPressed(_:)), for: UIControlEvents.touchUpInside)

    let menuBarItem = UIBarButtonItem(customView: menuBtn)
    let currWidth = menuBarItem.customView?.widthAnchor.constraint(equalToConstant: 24)
    currWidth?.isActive = true
    let currHeight = menuBarItem.customView?.heightAnchor.constraint(equalToConstant: 24)
    currHeight?.isActive = true
    self.navigationItem.leftBarButtonItem = menuBarItem
}