您需要设置UITextView
委托并在其中实现textViewDidChange：方法。不幸的是，我不知道是否可以在线获得快速文档。所有链接都转到Objective-
C文档。

该代码将如下所示：（ 已针对SWIFT 4.2更新 ）

class ViewController: UIViewController, UITextViewDelegate { //If your class is not conforms to the UITextViewDelegate protocol you will not be able to set it as delegate to UITextView

    @IBOutlet weak var bodyText: UITextView!

    override func viewDidLoad() {
        super.viewDidLoad()
        bodyText.delegate = self //Without setting the delegate you won't be able to track UITextView events
    }

    func textViewDidChange(_ textView: UITextView) { //Handle the text changes here
        print(textView.text); //the textView parameter is the textView where text was changed
    }
}