[Swift] 幫 UITextField 增加一個 done 按鈕

func addDoneButtonOnKeyboard(targetField:UITextField) {
	let doneToolbar: UIToolbar = UIToolbar(frame: CGRectMake(0, 0, 320, 50))
	doneToolbar.barStyle = UIBarStyle.BlackTranslucent

	let flexSpace = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FlexibleSpace, target: nil, action: nil)
	let done: UIBarButtonItem = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.Done, target: self, action: Selector("doneButtonAction"))

	var items = Array<UIBarButtonItem>()
	items.append(flexSpace)
	items.append(done)

	doneToolbar.items = items
	doneToolbar.sizeToFit()

	targetField.inputAccessoryView = doneToolbar
}