这里有一些东西可以被放到UIStackView中，它会使用内部高度约束来调整自己的大小。可能需要调整以适应特定的需求。

import UIKit

public protocol PlaceholderTextViewDelegate: class {
  func placeholderTextViewTextChanged(_ textView: PlaceholderTextView, text: String)
}

public class PlaceholderTextView: UIView {

  public weak var delegate: PlaceholderTextViewDelegate?
  private var heightConstraint: NSLayoutConstraint?

  public override init(frame: CGRect) {
    self.allowsNewLines = true

    super.init(frame: frame)

    self.heightConstraint = self.heightAnchor.constraint(equalToConstant: 0)
    self.heightConstraint?.isActive = true

    self.addSubview(self.placeholderTextView)
    self.addSubview(self.textView)

    self.pinToCorners(self.placeholderTextView)
    self.pinToCorners(self.textView)

    self.updateHeight()
  }

  public override func didMoveToSuperview() {
    super.didMoveToSuperview()

    self.updateHeight()
  }

  private func pinToCorners(_ view: UIView) {
    NSLayoutConstraint.activate([
      view.leadingAnchor.constraint(equalTo: self.leadingAnchor),
      view.trailingAnchor.constraint(equalTo: self.trailingAnchor),
      view.topAnchor.constraint(equalTo: self.topAnchor),
      view.bottomAnchor.constraint(equalTo: self.bottomAnchor)
    ])
  }

  // Accessors
  public var text: String? {
    didSet {
      self.textView.text = text
      self.textViewDidChange(self.textView)
      self.updateHeight()
    }
  }

  public var textColor: UIColor? {
    didSet {
      self.textView.textColor = textColor
      self.updateHeight()
    }
  }

  public var font: UIFont? {
    didSet {
      self.textView.font = font
      self.placeholderTextView.font = font
      self.updateHeight()
    }
  }

  public override var tintColor: UIColor? {
    didSet {
      self.textView.tintColor = tintColor
      self.placeholderTextView.tintColor = tintColor
    }
  }

  public var placeholderText: String? {
    didSet {
      self.placeholderTextView.text = placeholderText
      self.updateHeight()
    }
  }

  public var placeholderTextColor: UIColor? {
    didSet {
      self.placeholderTextView.textColor = placeholderTextColor
      self.updateHeight()
    }
  }

  public var allowsNewLines: Bool

  public required init?(coder _: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }

  private lazy var textView: UITextView = self.newTextView()
  private lazy var placeholderTextView: UITextView = self.newTextView()

  private func newTextView() -> UITextView {
    let textView = UITextView()
    textView.translatesAutoresizingMaskIntoConstraints = false
    textView.isScrollEnabled = false
    textView.delegate = self
    textView.backgroundColor = .clear
    return textView
  }

  private func updateHeight() {
    let maxSize = CGSize(width: self.frame.size.width, height: .greatestFiniteMagnitude)

    let textViewSize = self.textView.sizeThatFits(maxSize)
    let placeholderSize = self.placeholderTextView.sizeThatFits(maxSize)

    let maxHeight = ceil(CGFloat.maximum(textViewSize.height, placeholderSize.height))

    self.heightConstraint?.constant = maxHeight
  }
}

extension PlaceholderTextView: UITextViewDelegate {
  public func textViewDidChangeSelection(_: UITextView) {
    self.placeholderTextView.alpha = self.textView.text.isEmpty ? 1 : 0
    self.updateHeight()
  }

  public func textViewDidChange(_: UITextView) {
    self.delegate?.placeholderTextViewTextChanged(self, text: self.textView.text)
  }

  public func textView(_: UITextView, shouldChangeTextIn _: NSRange,
                       replacementText text: String) -> Bool {
    let containsNewLines = text.rangeOfCharacter(from: .newlines)?.isEmpty == .some(false)
    guard !containsNewLines || self.allowsNewLines else { return false }

    return true
  }
}

斯威夫特3.1

这个扩展为我工作得很好:https://github.com/devxoul/UITextView-Placeholder

下面是一个代码片段:

通过pod安装:

pod 'UITextView+Placeholder', '~> 1.2'

将它导入到类中

import UITextView_Placeholder

并添加占位符属性到您已经创建的UITextView

textView.placeholder = "Put some detail"

这是…… 这里是它的外观(第三个框是一个UITextView)

有我的简单版本的UITextView与占位符。主要思想是:

隐藏占位符，如果用户开始编辑和占位符是可见的 如果用户结束编辑并且文本视图的文本为空，则显示占位符。

class PlaceholderTextView: UITextView {

    var placeholder = "" {
        didSet {
            if isPlaceholderVisible {
                showPlaceholder()
            }
        }
    }

    var isPlaceholderVisible = true {
        didSet {
            isPlaceholderVisible ? showPlaceholder() : hidePlaceholder()
        }
    }

    init() {
        super.init(frame: .zero, textContainer: nil)
        delegate = self
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    private func showPlaceholder() {
        text = placeholder
        // Set other things like color of text for placeholder, ...
    }

    private func hidePlaceholder() {
        text = ""
        // Set other things like color of text for normal input, ...
    }

}

extension PlaceholderTextView: UITextViewDelegate {
    func textViewDidBeginEditing(_ textView: UITextView) {
        if isPlaceholderVisible {
            isPlaceholderVisible = false
        }
    }

    func textViewDidEndEditing(_ textView: UITextView) {
        if text.isEmpty {
            isPlaceholderVisible = true
        }
    }
}

没有这样的属性在ios添加占位符直接在TextView，而你可以添加一个标签和显示/隐藏在TextView的变化。SWIFT 2.0，确保实现textviewdelegate

func textViewDidChange(TextView: UITextView)
{

 if  txtShortDescription.text == ""
    {
        self.lblShortDescription.hidden = false
    }
    else
    {
        self.lblShortDescription.hidden = true
    }

}

迅速的回答

这是一个自定义类，用于动画占位符。

class CustomTextView: UITextView {
    
    //   MARK: - public
    
    public var placeHolderText: String? = "Enter Reason.."
    
    public lazy var placeHolderLabel: UILabel! = {
        let placeHolderLabel = UILabel(frame: .zero)
        placeHolderLabel.numberOfLines = 0
        placeHolderLabel.backgroundColor = .clear
        placeHolderLabel.alpha = 0.5
        return placeHolderLabel
    }()
    
    //   MARK: - Init
    
    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        enableNotifications()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        enableNotifications()
    }
    
    func setup() {
        placeHolderLabel.frame = CGRect(x: 8, y: 8, width: self.bounds.size.width - 16, height: 15)
        placeHolderLabel.sizeToFit()
    }
    
    //   MARK: - Cycle
    
    override func awakeFromNib() {
        super.awakeFromNib()
        
        textContainerInset = UIEdgeInsets(top: 8, left: 5, bottom: 8, right: 8)
        returnKeyType = .done
        addSubview(placeHolderLabel)
        placeHolderLabel.frame = CGRect(x: 8, y: 8, width: self.bounds.size.width - 16, height: 15)
        placeHolderLabel.textColor = textColor
        placeHolderLabel.font = font
        placeHolderLabel.text = placeHolderText
        bringSubviewToFront(placeHolderLabel)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        setup()
    }
    
    //   MARK: - Notifications
    
    private func enableNotifications() {
        NotificationCenter.default.addObserver(self, selector: #selector(textDidChangeNotification(_:)), name: UITextView.textDidChangeNotification , object: nil)
    }
    
    @objc func textDidChangeNotification(_ notify: Notification) {
        guard self == notify.object as? UITextView else { return }
        guard placeHolderText != nil else { return }
        
        UIView.animate(withDuration: 0.25, animations: {
            self.placeHolderLabel.alpha = (self.text.count == 0) ? 0.5 : 0
        }, completion: nil)
    }
    
}

以下是我解决这个问题的方法(Swift 4):

这个想法是做出最简单的解决方案，允许使用不同颜色的占位符，调整占位符大小，不会覆盖委托，同时保持所有UITextView函数正常工作。

import UIKit

class PlaceholderTextView: UITextView {
    var placeholderColor: UIColor = .lightGray
    var defaultTextColor: UIColor = .black

    private var isShowingPlaceholder = false {
        didSet {
            if isShowingPlaceholder {
                text = placeholder
                textColor = placeholderColor
            } else {
                textColor = defaultTextColor
            }
        }
    }

    var placeholder: String? {
        didSet {
            isShowingPlaceholder = !hasText
        }
    }

    @objc private func textViewDidBeginEditing(notification: Notification) {
        textColor = defaultTextColor
        if isShowingPlaceholder { text = nil }
    }

    @objc private func textViewDidEndEditing(notification: Notification) {
        isShowingPlaceholder = !hasText
    }

    // MARK: - Construction -
    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        setup()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }

    private func setup() {
        NotificationCenter.default.addObserver(self, selector: #selector(textViewDidBeginEditing(notification:)), name: UITextView.textDidBeginEditingNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(textViewDidEndEditing(notification:)), name: UITextView.textDidEndEditingNotification, object: nil)
    }

    // MARK: - Destruction -
    deinit { NotificationCenter.default.removeObserver(self) }
}