1: NSNotificationCenter.defaultCenter().addObserver(self, selector: "textDidChange", name: UITextFieldTextDidChangeNotification, object: nil)
1: deinit{
2: NSNotificationCenter.defaultCenter().removeObserver(self)
3: }
NSNotificationCenter监听TextField文字变化
原文：http://www.cnblogs.com/zeyang/p/4493805.html