如何在UITextView中添加占位符,类似于你可以为UITextField设置的占位符,在Swift中?


当前回答

迅速:

添加你的TextView @IBOutlet:

@IBOutlet weak var txtViewMessage: UITextView!

在viewWillAppear方法中,添加以下内容:

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    txtViewMessage.delegate = self    // Give TextViewMessage delegate Method
    
    txtViewMessage.text = "Place Holder Name"
    txtViewMessage.textColor = UIColor.lightGray
}

请添加委托使用扩展(UITextViewDelegate):

// MARK: - UITextViewDelegate
extension ViewController: UITextViewDelegate {

    func textViewDidBeginEditing(_ textView: UITextView) {

        if !txtViewMessage.text!.isEmpty && txtViewMessage.text! == "Place Holder Name" {
            txtViewMessage.text = ""
            txtViewMessage.textColor = UIColor.black
        }
    }

    func textViewDidEndEditing(_ textView: UITextView) {
    
        if txtViewMessage.text.isEmpty {
            txtViewMessage.text = "Place Holder Name"
            txtViewMessage.textColor = UIColor.lightGray
        }
    }
}

其他回答

Swift 4、4.2和5

[![@IBOutlet var detailTextView: UITextView!

override func viewDidLoad() {
        super.viewDidLoad()
        detailTextView.delegate = self
}

extension ContactUsViewController : UITextViewDelegate {

    public func textViewDidBeginEditing(_ textView: UITextView) {
        if textView.text == "Write your message here..." {
            detailTextView.text = ""
            detailTextView.textColor = UIColor.init(red: 0/255, green: 0/255, blue: 0/255, alpha: 0.86)

        }
        textView.becomeFirstResponder()
    }

    public func textViewDidEndEditing(_ textView: UITextView) {

        if textView.text == "" {
            detailTextView.text = "Write your message here..."
            detailTextView.textColor = UIColor.init(red: 0/255, green: 0/255, blue: 0/255, alpha: 0.30)
        }
        textView.resignFirstResponder()
    }
[![}][1]][1]

迅速:

以编程方式或通过Interface Builder添加你的文本视图,如果是最后一个,创建outlet:

@IBOutlet weak var yourTextView: UITextView!

请添加委托(UITextViewDelegate):

class ViewController: UIViewController, UITextViewDelegate {

在viewDidLoad方法中,添加如下内容:

override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

    yourTextView.delegate = self
    yourTextView.text = "Placeholder text goes right here..."
    yourTextView.textColor = UIColor.lightGray

现在让我来介绍一下神奇的部分,添加这个函数:

func textViewDidBeginEditing(_ textView: UITextView) {

    if yourTextView.textColor == UIColor.lightGray {
        yourTextView.text = ""
        yourTextView.textColor = UIColor.black
    }
}

请注意,这将在编辑开始时执行,在那里我们将检查条件来告知状态,使用color属性。 设置文本为nil我不建议。在此之后,我们将文本颜色设置为所需的颜色,在本例中为黑色。

现在也添加这个函数:

func textViewDidEndEditing(_ textView: UITextView) {

    if yourTextView.text == "" {

        yourTextView.text = "Placeholder text ..."
        yourTextView.textColor = UIColor.lightGray
    }
}

让我坚持一下,不要与零进行比较,我已经试过了,它不会起作用。然后我们将值设置回占位符样式,并将颜色设置回占位符颜色,因为这是在textViewDidBeginEditing中检查的条件。


浮动的占位符


将占位符标签放置在文本视图之上,通过跟踪文本视图字符计数的变化来设置其字体、颜色和管理占位符可见性,这是简单、安全且可靠的。

斯威夫特5:

class NotesViewController : UIViewController {

    @IBOutlet var textView : UITextView!
    var placeholderLabel : UILabel!
        
    override func viewDidLoad() {
        super.viewDidLoad()
    
        textView.delegate = self
        placeholderLabel = UILabel()
        placeholderLabel.text = "Enter some text..."
        placeholderLabel.font = .italicSystemFont(ofSize: (textView.font?.pointSize)!)
        placeholderLabel.sizeToFit()
        textView.addSubview(placeholderLabel)
        placeholderLabel.frame.origin = CGPoint(x: 5, y: (textView.font?.pointSize)! / 2)
        placeholderLabel.textColor = .tertiaryLabel
        placeholderLabel.isHidden = !textView.text.isEmpty
    }
}

extension NotesViewController : UITextViewDelegate {
    func textViewDidChange(_ textView: UITextView) {
        placeholderLabel.isHidden = !textView.text.isEmpty
    }
}

与这篇文章中几乎所有的答案相反,UITextView确实有一个占位符属性。由于我无法理解的原因,它只在IB中出现,例如:

<userDefinedRuntimeAttributes>
  <userDefinedRuntimeAttribute type="string" keyPath="placeholder" value="My Placeholder"/>
</userDefinedRuntimeAttributes>

因此,如果你正在使用故事板,一个静态占位符就足够了,只需在检查器上设置属性。

你也可以像这样在代码中设置这个属性:

textView.setValue("My Placeholder", forKeyPath: "placeholder")

它的多云天气,这是通过私有API访问,因为属性是暴露的。

我还没有尝试过用这种方法提交。但我将很快以这种方式提交,并将相应地更新这个答案。

更新:

我已经在多个版本中发布了这个代码,苹果没有任何问题。

更新: 这将只适用于Xcode pre 11.2

var placeholderLabel : UILabel!
  textviewDescription.delegate = self
    placeholderLabel = UILabel()
    placeholderLabel.text = "Add a description"

   func textViewDidChange(_ textView: UITextView) {
             placeholderLabel.isHidden = !textviewDescription.text.isEmpty
    }