Add UIToolBar to all keyboards (swift)

For swift 4 you can use this:-

extension UIViewController : UITextFieldDelegate {
    func addToolBar(textField: UITextField){
        var toolBar = UIToolbar()
        toolBar.barStyle = UIBarStyle.default
        toolBar.isTranslucent = true
        toolBar.tintColor = UIColor(red: 76/255, green: 217/255, blue: 100/255, alpha: 1)
        var doneButton = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.done, target: self, action: "donePressed")
        var cancelButton = UIBarButtonItem(title: "Cancel", style: UIBarButtonItemStyle.plain, target: self, action: "cancelPressed")
        var spaceButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.flexibleSpace, target: nil, action: nil)
        toolBar.setItems([cancelButton, spaceButton, doneButton], animated: false)
        toolBar.isUserInteractionEnabled = true
        toolBar.sizeToFit()

        textField.delegate = self
        textField.inputAccessoryView = toolBar
    }
    func donePressed(){
        view.endEditing(true)
    }
    func cancelPressed(){
        view.endEditing(true) // or do something
    }
}

Use

override func viewDidLoad() {
      super.viewDidLoad()
      addToolBar(addressField)
 }

Thanks to Glorfindel's suggestion and ncerezo's sample code I solved my problem using extensions.

extension UIViewController: UITextFieldDelegate{
    func addToolBar(textField: UITextField){
        var toolBar = UIToolbar()
        toolBar.barStyle = UIBarStyle.Default
        toolBar.translucent = true
        toolBar.tintColor = UIColor(red: 76/255, green: 217/255, blue: 100/255, alpha: 1)
        var doneButton = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.Done, target: self, action: "donePressed")
        var cancelButton = UIBarButtonItem(title: "Cancel", style: UIBarButtonItemStyle.Plain, target: self, action: "cancelPressed")
        var spaceButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FlexibleSpace, target: nil, action: nil)
        toolBar.setItems([cancelButton, spaceButton, doneButton], animated: false)
        toolBar.userInteractionEnabled = true
        toolBar.sizeToFit()

        textField.delegate = self
        textField.inputAccessoryView = toolBar
    }
    func donePressed(){
        view.endEditing(true)
    }
    func cancelPressed(){
        view.endEditing(true) // or do something
    }
}

Though I still need to call the code below on all of my textfields. I feel like there may be a better way without having to call the function on every textField, but for now this is definitely more reusable.

override func viewDidLoad() {
    super.viewDidLoad()
    addToolBar(addressField)
}

equivalent of vivian version in swift 3:

extension UIViewController: UITextFieldDelegate {
    func addToolBar(textField: UITextField) {
        let toolBar = UIToolbar()
        toolBar.barStyle = .default
        toolBar.isTranslucent = true
        toolBar.tintColor = UIColor(red: 76 / 255, green: 217 / 255, blue: 100 / 255, alpha: 1)
        let doneButton = UIBarButtonItem(title: "Done", style: .done, target: self, action: #selector(donePressed))
        let cancelButton = UIBarButtonItem(title: "Cancel", style: .plain, target: self, action: #selector(cancelPressed))
        let spaceButton = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
        toolBar.setItems([cancelButton, spaceButton, doneButton], animated: false)


        toolBar.isUserInteractionEnabled = true
        toolBar.sizeToFit()

        textField.delegate = self
        textField.inputAccessoryView = toolBar
    }

    func donePressed() {
        view.endEditing(true)
    }

    func cancelPressed() {
        view.endEditing(true) // or do something
    }
}