未为 UITextView 触发的委托协议函数

Question

我有这个 swift 文件，我试图在其中创建自定义 class 来处理一页上多个文本视图的占位符。我更喜欢单独的 class，因为我认为它可以更清晰地处理多个视图。问题是，当这些事件发生时，函数 textViewDidEndEditing 和 textViewDidBeginEditing 没有被调用。

我已经通过将 PostPage 设置为委托成功地工作了，但是我不知道如何使用多个 UITextView 来做到这一点。

这是我的代码：

import UIKit

class PostPage: UIViewController, UITextViewDelegate {

    @IBOutlet weak var eventDescription: UITextView!
    @IBOutlet weak var eventTitle: UITextView!

    var placeholderShowing = true

    override func viewDidLoad() {
        super.viewDidLoad()

        // Add a placeholder for the text
        let ph_descr = PlaceHolderHandler(placeholderText: "Description", textBox: eventDescription)
        eventDescription.delegate = ph_descr

        let ph_title = PlaceHolderHandler(placeholderText: "Title", textBox: eventTitle)
        eventTitle.delegate = ph_title
    }

}

 class PlaceHolderHandler: NSObject, UITextViewDelegate {

    var placeholderShowing = true
    var placeholderText = ""

    required init(placeholderText: String, textBox: UITextView) {
        super.init()
        self.placeholderText = placeholderText
        textBox.text = placeholderText
        textBox.textColor = UIColor.lightGray
    }


    // MARK:- UITextViewDelegates

    public func textViewDidBeginEditing(_ textView: UITextView) {
        if self.placeholderShowing {
            textView.text = ""
            textView.textColor = UIColor.black
            self.placeholderShowing = false
        }

    }

    public func textViewDidEndEditing(_ textView: UITextView) {
        if textView.text == "" {
            textView.text = "Description"
            textView.textColor = UIColor.lightGray
            self.placeholderShowing = true
        }
    }
 }

当我 select 任一 UITextView 时，我希望调用相应的函数，并相应地调整文本。

Answer 1

您需要保留 phDescr 和 phTitle，因为在您的代码中它们是局部变量，因此在 viewDidLoad

的末尾取消分配

import UIKit

class PostPage: UIViewController, UITextViewDelegate {

    @IBOutlet weak var eventDescription: UITextView!
    @IBOutlet weak var eventTitle: UITextView!

    var placeholderShowing = true

    var phDescr, phTitle:PlaceHolderHandler!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Add a placeholder for the text
        phDescr = PlaceHolderHandler(placeholderText: "Description", textBox: eventDescription)
        eventDescription.delegate = phDescr

        phTitle = PlaceHolderHandler(placeholderText: "Title", textBox: eventTitle)
        eventTitle.delegate = phTitle
    }

}

也使用驼峰式命名变量

I've had it successfully work by setting the PostPage to the delegate, but I don't see how I could do that with multiple UITextView

当然你可以将两者的委托设置为 PostPage 并知道哪一个是完整的使用

func textViewDidBeginEditing(_ textView: UITextView) {
   if textView == eventDescription {
   }
   else {  // eventTitle
   }
}

未为 UITextView 触发的委托协议函数

Delegate protocol functions not triggered for UITextView

delegates

uitextviewdelegate

swift