Make a UIBarButtonItem disappear using swift IOS

// Nice answer haiLong, I think as an extension this is more convenient.

extension UIBarButtonItem {
    var isHidden: Bool {
        get {
            return !isEnabled && tintColor == .clear
        }
        set {
            tintColor = newValue ? .clear : nil
            isEnabled = !newValue
        }
    }
}

EDIT: Removed forced unwrapping and fixed enabled value.

Use the property enabled and tintColor

    let barButtonItem:UIBarButtonItem? = nil

    if isHidden{
        barButtonItem?.enabled      = false
        barButtonItem?.tintColor    = UIColor.clearColor()
    }else{
        barButtonItem?.enabled      = true
        barButtonItem?.tintColor    = nil
    }

Do you really want to hide/show creeLigueBouton? It is instead much easier to enable/disable your UIBarButtonItems. You would do this with a few lines:

if(condition == true) {
    creeLigueBouton.enabled = false
} else {
    creeLigueBouton.enabled = true
}

This code can even be rewritten in a shorter way:

creeLigueBouton.enabled = !creeLigueBouton.enabled

Let's see it in a UIViewController subclass:

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var creeLigueBouton: UIBarButtonItem!

    @IBAction func hide(sender: AnyObject) {
        creeLigueBouton.enabled = !creeLigueBouton.enabled
    }

}

---

If you really want to show/hide creeLigueBouton, you can use the following code:

import UIKit

class ViewController: UIViewController {

    var condition: Bool = true
    var creeLigueBouton: UIBarButtonItem! //Don't create an IBOutlet

    @IBAction func hide(sender: AnyObject) {
        if(condition == true) {
            navigationItem.rightBarButtonItems = []
            condition = false
        } else {
            navigationItem.rightBarButtonItems = [creeLigueBouton]
            condition = true
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        creeLigueBouton = UIBarButtonItem(title: "Creer", style: UIBarButtonItemStyle.Plain, target: self, action: "creerButtonMethod")
        navigationItem.rightBarButtonItems = [creeLigueBouton]
    }

    func creerButtonMethod() {
        print("Bonjour")
    }

}