Swift -我写了一个继承了UITextView的类，并添加了一个UILabel作为子视图作为占位符。

  import UIKit
  @IBDesignable
  class HintedTextView: UITextView {

      @IBInspectable var hintText: String = "hintText" {
          didSet{
              hintLabel.text = hintText
          }
      }

      private lazy var hintLabel: UILabel = {
          let label = UILabel()
          label.font = UIFont.systemFontOfSize(16)
          label.textColor = UIColor.lightGrayColor()
          label.translatesAutoresizingMaskIntoConstraints = false
          return label
      }()


      override init(frame: CGRect, textContainer: NSTextContainer?) {
          super.init(frame: frame, textContainer: textContainer)
          setupView()
      }

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

      override func prepareForInterfaceBuilder() {
         super.prepareForInterfaceBuilder()
         setupView()
      }

      private func setupView() {

        translatesAutoresizingMaskIntoConstraints = false
        delegate = self
        font = UIFont.systemFontOfSize(16)

        addSubview(hintLabel)

        NSLayoutConstraint.activateConstraints([

           hintLabel.leftAnchor.constraintEqualToAnchor(leftAnchor, constant: 4),
           hintLabel.rightAnchor.constraintEqualToAnchor(rightAnchor, constant: 8),
           hintLabel.topAnchor.constraintEqualToAnchor(topAnchor, constant: 4),
           hintLabel.heightAnchor.constraintEqualToConstant(30)
         ])
        }

      override func layoutSubviews() {
        super.layoutSubviews()
        setupView()
     }

}

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
        }
    }
}

我知道这是一个老问题，但想分享我认为是一个有用的方式扩展UITextView有placeholderText和placeholderColor字段。基本上你将UITextView转换为UITextField，然后设置attributedPlaceholder字段。PlaceholderText和placeholderColor是IBInspectable字段，所以它们的值可以在IB中设置，并与UITextField占位符功能完全相同。

UITextView+Extend.h

#import <UIKit/UIKit.h>

@interface UITextView (Extend)

@property (nonatomic) IBInspectable NSString *placeholderText;
@property (nonatomic) IBInspectable UIColor *placeholderColor;

@end

UITextView+Extend.m

#import "UITextView+Extend.h"
#import "objc/runtime.h"

@implementation UITextView (Extend)

- (void)setPlaceholderText:(NSString *)placeholderText
{
    objc_setAssociatedObject(self, @selector(placeholderText), placeholderText, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    [self updatePlaceholderText];
}

- (NSString*)placeholderText
{
    return objc_getAssociatedObject(self, @selector(placeholderText));
}

- (void)setPlaceholderColor:(UIColor *)placeholderColor
{
    objc_setAssociatedObject(self, @selector(placeholderColor), placeholderColor, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    [self updatePlaceholderText];
}

- (UIColor*)placeholderColor
{
    return objc_getAssociatedObject(self, @selector(placeholderColor));
}

- (void)updatePlaceholderText
{
    NSString *text = self.placeholderText;
    UIColor *color = self.placeholderColor;
    if(text && color)
    {
        UITextField *textField = (UITextField*)self;
        textField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:text attributes:@{NSForegroundColorAttributeName:color}];
    }
}

@end

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

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

这是我准备使用的解决方案，如果您正在处理多个文本视图

func textViewShouldBeginEditing(textView: UITextView) -> Bool {        
    // Set cursor to the beginning if placeholder is set
    if textView.textColor == UIColor.lightGrayColor() {
        textView.selectedTextRange = textView.textRangeFromPosition(textView.beginningOfDocument, toPosition: textView.beginningOfDocument)
    }

    return true
}

func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {
    // Remove placeholder
    if textView.textColor == UIColor.lightGrayColor() && text.characters.count > 0 {
        textView.text = ""
        textView.textColor = UIColor.blackColor()
    }

    if text == "\n" {
        textView.resignFirstResponder()
        return false
    }

    return true
}

func textViewDidChange(textView: UITextView) {
    // Set placeholder if text is empty
    if textView.text.isEmpty {
        textView.text = NSLocalizedString("Hint", comment: "hint")
        textView.textColor = UIColor.lightGrayColor()
        textView.selectedTextRange = textView.textRangeFromPosition(textView.beginningOfDocument, toPosition: textView.beginningOfDocument)
    }
}

func textViewDidChangeSelection(textView: UITextView) {
    // Set cursor to the beginning if placeholder is set
    let firstPosition = textView.textRangeFromPosition(textView.beginningOfDocument, toPosition: textView.beginningOfDocument)

    // Do not change position recursively
    if textView.textColor == UIColor.lightGrayColor() && textView.selectedTextRange != firstPosition {
        textView.selectedTextRange = firstPosition
    }
}

在swift2.2:

public class CustomTextView: UITextView {

private struct Constants {
    static let defaultiOSPlaceholderColor = UIColor(red: 0.0, green: 0.0, blue: 0.0980392, alpha: 0.22)
}
private let placeholderLabel: UILabel = UILabel()

private var placeholderLabelConstraints = [NSLayoutConstraint]()

@IBInspectable public var placeholder: String = "" {
    didSet {
        placeholderLabel.text = placeholder
    }
}

@IBInspectable public var placeholderColor: UIColor = CustomTextView.Constants.defaultiOSPlaceholderColor {
    didSet {
        placeholderLabel.textColor = placeholderColor
    }
}

override public var font: UIFont! {
    didSet {
        placeholderLabel.font = font
    }
}

override public var textAlignment: NSTextAlignment {
    didSet {
        placeholderLabel.textAlignment = textAlignment
    }
}

override public var text: String! {
    didSet {
        textDidChange()
    }
}

override public var attributedText: NSAttributedString! {
    didSet {
        textDidChange()
    }
}

override public var textContainerInset: UIEdgeInsets {
    didSet {
        updateConstraintsForPlaceholderLabel()
    }
}

override public init(frame: CGRect, textContainer: NSTextContainer?) {
    super.init(frame: frame, textContainer: textContainer)
    commonInit()
}

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

private func commonInit() {
    NSNotificationCenter.defaultCenter().addObserver(self,
                                                     selector: #selector(textDidChange),
                                                     name: UITextViewTextDidChangeNotification,
                                                     object: nil)

    placeholderLabel.font = font
    placeholderLabel.textColor = placeholderColor
    placeholderLabel.textAlignment = textAlignment
    placeholderLabel.text = placeholder
    placeholderLabel.numberOfLines = 0
    placeholderLabel.backgroundColor = UIColor.clearColor()
    placeholderLabel.translatesAutoresizingMaskIntoConstraints = false
    addSubview(placeholderLabel)
    updateConstraintsForPlaceholderLabel()
}

private func updateConstraintsForPlaceholderLabel() {
    var newConstraints = NSLayoutConstraint.constraintsWithVisualFormat("H:|-(\(textContainerInset.left + textContainer.lineFragmentPadding))-[placeholder]",
                                                                        options: [],
                                                                        metrics: nil,
                                                                        views: ["placeholder": placeholderLabel])
    newConstraints += NSLayoutConstraint.constraintsWithVisualFormat("V:|-(\(textContainerInset.top))-[placeholder]",
                                                                     options: [],
                                                                     metrics: nil,
                                                                     views: ["placeholder": placeholderLabel])
    newConstraints.append(NSLayoutConstraint(
        item: placeholderLabel,
        attribute: .Width,
        relatedBy: .Equal,
        toItem: self,
        attribute: .Width,
        multiplier: 1.0,
        constant: -(textContainerInset.left + textContainerInset.right + textContainer.lineFragmentPadding * 2.0)
        ))
    removeConstraints(placeholderLabelConstraints)
    addConstraints(newConstraints)
    placeholderLabelConstraints = newConstraints
}

@objc private func textDidChange() {
    placeholderLabel.hidden = !text.isEmpty
}

public override func layoutSubviews() {
    super.layoutSubviews()
    placeholderLabel.preferredMaxLayoutWidth = textContainer.size.width - textContainer.lineFragmentPadding * 2.0
}

deinit {
    NSNotificationCenter.defaultCenter().removeObserver(self,
                                                        name: UITextViewTextDidChangeNotification,
                                                        object: nil)
}

}

在swift3:

import UIKit

类 CustomTextView： { UITextView

private struct Constants {
    static let defaultiOSPlaceholderColor = UIColor(red: 0.0, green: 0.0, blue: 0.0980392, alpha: 0.22)
}
private let placeholderLabel: UILabel = UILabel()

private var placeholderLabelConstraints = [NSLayoutConstraint]()

@IBInspectable public var placeholder: String = "" {
    didSet {
        placeholderLabel.text = placeholder
    }
}

@IBInspectable public var placeholderColor: UIColor = CustomTextView.Constants.defaultiOSPlaceholderColor {
    didSet {
        placeholderLabel.textColor = placeholderColor
    }
}

override public var font: UIFont! {
    didSet {
        placeholderLabel.font = font
    }
}

override public var textAlignment: NSTextAlignment {
    didSet {
        placeholderLabel.textAlignment = textAlignment
    }
}

override public var text: String! {
    didSet {
        textDidChange()
    }
}

override public var attributedText: NSAttributedString! {
    didSet {
        textDidChange()
    }
}

override public var textContainerInset: UIEdgeInsets {
    didSet {
        updateConstraintsForPlaceholderLabel()
    }
}

override public init(frame: CGRect, textContainer: NSTextContainer?) {
    super.init(frame: frame, textContainer: textContainer)
    commonInit()
}

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

private func commonInit() {
    NotificationCenter.default.addObserver(self,
                                                     selector: #selector(textDidChange),
                                                     name: NSNotification.Name.UITextViewTextDidChange,
                                                     object: nil)

    placeholderLabel.font = font
    placeholderLabel.textColor = placeholderColor
    placeholderLabel.textAlignment = textAlignment
    placeholderLabel.text = placeholder
    placeholderLabel.numberOfLines = 0
    placeholderLabel.backgroundColor = UIColor.clear
    placeholderLabel.translatesAutoresizingMaskIntoConstraints = false
    addSubview(placeholderLabel)
    updateConstraintsForPlaceholderLabel()
}

private func updateConstraintsForPlaceholderLabel() {
    var newConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:|-(\(textContainerInset.left + textContainer.lineFragmentPadding))-[placeholder]",
        options: [],
        metrics: nil,
        views: ["placeholder": placeholderLabel])
    newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "V:|-(\(textContainerInset.top))-[placeholder]",
        options: [],
        metrics: nil,
        views: ["placeholder": placeholderLabel])
    newConstraints.append(NSLayoutConstraint(
        item: placeholderLabel,
        attribute: .width,
        relatedBy: .equal,
        toItem: self,
        attribute: .width,
        multiplier: 1.0,
        constant: -(textContainerInset.left + textContainerInset.right + textContainer.lineFragmentPadding * 2.0)
    ))
    removeConstraints(placeholderLabelConstraints)
    addConstraints(newConstraints)
    placeholderLabelConstraints = newConstraints
}

@objc private func textDidChange() {
    placeholderLabel.isHidden = !text.isEmpty
}

public override func layoutSubviews() {
    super.layoutSubviews()
    placeholderLabel.preferredMaxLayoutWidth = textContainer.size.width - textContainer.lineFragmentPadding * 2.0
}

deinit {
    NotificationCenter.default.removeObserver(self,
                                                        name: NSNotification.Name.UITextViewTextDidChange,
                                                        object: nil)
}

}

我用swift写了一个类。您需要在需要的时候导入这个类。