let screenSize = UIScreen.mainScreen().bounds.size
        let textView = UITextView(frame: CGRectMake(0, 20, screenSize.width, 200))
        textView.font = UIFont.systemFontOfSize(20)
        textView.selectable = false
        textView.scrollEnabled = true
        textView.editable = true
        textView.textColor = UIColor.whiteColor()
        textView.backgroundColor = UIColor.blackColor()
        textView.text = "The UITextView class implements the behavior for a scrollable, multiline text region. The class supports the display of text using custom style information and also supports text editing. You typically use a text view to display multiple lines of text, such as when displaying the body of a large text document."
        textView.textAlignment = .Center
        textView.textContainerInset = UIEdgeInsetsMake(60, 0, 0, 0)
        textView.keyboardType = .Default
        textView.returnKeyType = .Default
        view.addSubview(textView)
        
        self.textView = textView

        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(ViewController.textViewDidBeginEdit(_:)), name: UITextViewTextDidBeginEditingNotification, object: textView)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(ViewController.textViewTextDidChange(_:)), name: UITextViewTextDidChangeNotification, object: textView)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(ViewController.textViewDidEndEdit(_:)), name: UITextViewTextDidEndEditingNotification, object: textView)

    func textViewDidBeginEdit(notification: NSNotification) {
        print(notification.name)
    }
    
    func textViewTextDidChange(notification: NSNotification) {
        print(notification.object)
    }
    
    func textViewDidEndEdit(notification: NSNotification) {
        print(notification.name)
    }

    deinit{
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UITextViewTextDidChangeNotification, object: textView)
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UITextViewTextDidEndEditingNotification, object: textView)
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UITextViewTextDidBeginEditingNotification, object: textView)
    }

extension ViewController: UITextViewDelegate {
    // 是否应该开始编辑
    func textViewShouldBeginEditing(textView: UITextView) -> Bool {
        print("textViewShouldBeginEditing")
        return true
    }
    
    // 是否应该停止编辑
    func textViewShouldEndEditing(textView: UITextView) -> Bool {
        print("textViewShouldEndEditing")
        return true
    }
    
    // 文字视图已经开始编辑
    func textViewDidBeginEditing(textView: UITextView) {
        print("textViewDidBeginEditing")
    }
    
    // 文字视图已经停止编辑
    func textViewDidEndEditing(textView: UITextView) {
        print("textViewDidEndEditing")
    }
    
    // 文字视图是否允许替换文字，每当有文字要被输入或删除都会先调用这个方法
    func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {
        if text == "\n" {
            textView.resignFirstResponder()
            return false
        }
        return true
    }
    
    // 文字视图文字已经被替换
    func textViewDidChange(textView: UITextView) {
        print("textViewDidChange")
    }
    
    // 每当有一组文字被选中或删除输入、放大镜的移动，都会调用此方法
    func textViewDidChangeSelection(textView: UITextView) {
        print("textViewDidChangeSelection")
    }