另一个解决方案

import UIKit

protocol PlaceholderTextViewDelegate: class {

    func placeholderTextViewDidChangeText(_ text: String)
    func placeholderTextViewDidEndEditing(_ text: String)
}

final class PlaceholderTextView: UITextView {

    weak var notifier: PlaceholderTextViewDelegate?
    var ignoreEnterAction: Bool = true

    var placeholder: String? {
        didSet {
            text = placeholder
            selectedRange = NSRange(location: 0, length: 0)
        }
    }

    var placeholderColor = UIColor.lightGray {
        didSet {
            if text == placeholder {
                textColor = placeholderColor
            }
        }
    }
    var normalTextColor = UIColor.lightGray

    var placeholderFont = UIFont.sfProRegular(28)

    fileprivate var placeholderLabel: UILabel?

    // MARK: - LifeCycle

    override var text: String? {
        didSet {
            if text == placeholder {
                textColor = placeholderColor
            } else {
                textColor = normalTextColor
            }
        }
    }

    init() {
        super.init(frame: CGRect.zero, textContainer: nil)
        awakeFromNib()
    }

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

    override func awakeFromNib() {
        super.awakeFromNib()

        self.delegate = self
    }
}

extension PlaceholderTextView: UITextViewDelegate {

    // MARK: - UITextViewDelegate
    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {

        if text == "" && textView.text == placeholder {
            return false
        }

        if let placeholder = placeholder,
            textView.text == placeholder,
            range.location <= placeholder.count {
            textView.text = ""
        }

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

    func textViewDidChange(_ textView: UITextView) {
        if let placeholder = placeholder {
            textView.text = textView.text.replacingOccurrences(of: placeholder, with: "")
        }

        if let placeholder = placeholder,
            text?.isEmpty == true {
            text = placeholder
            textColor = placeholderColor

            selectedRange = NSRange(location: 0, length: 0)
        } else {
            textColor = normalTextColor
        }

        notifier?.placeholderTextViewDidChangeText(textView.text)
    }

    func textViewDidChangeSelection(_ textView: UITextView) {
        if let placeholder = placeholder,
            text == placeholder {
            selectedRange = NSRange(location: 0, length: 0)
        }
    }

    func textViewDidEndEditing(_ textView: UITextView) {
        notifier?.placeholderTextViewDidEndEditing(textView.text)

        if let placeholder = placeholder,
            text?.isEmpty == true {
            text = placeholder
            textColor = placeholderColor
            selectedRange = NSRange(location: 0, length: 0)
        } else {
            textColor = normalTextColor
        }
    }
}

结果:

这里有一个更简单的解决方案，它的行为完全像UITextField的占位符，但不需要绘制自定义视图，或辞职第一响应器。

- (void) textViewDidChange:(UITextView *)textView{

    if (textView.text.length == 0){
        textView.textColor = [UIColor lightGrayColor];
        textView.text = placeholderText;
        [textView setSelectedRange:NSMakeRange(0, 0)];
        isPlaceholder = YES;

    } else if (isPlaceholder && ![textView.text isEqualToString:placeholderText]) {
        textView.text = [textView.text substringToIndex:1];
        textView.textColor = [UIColor blackColor];
        isPlaceholder = NO;
    }

}

(else if语句中的第二个检查是针对没有输入任何内容且用户按下退格键的情况)

只需要将你的类设置为UITextViewDelegate。在viewDidLoad中，你应该这样初始化

- (void) viewDidLoad{
    // initialize placeholder text
    placeholderText = @"some placeholder";
    isPlaceholder = YES;
    self.someTextView.text = placeholderText;
    self.someTextView.textColor = [UIColor lightGrayColor];
    [self.someTextView setSelectedRange:NSMakeRange(0, 0)];

    // assign UITextViewDelegate
    self.someTextView.delegate = self;
}

下面是“SAMTextView”ObjC代码的Swift端口，作为对这个问题的第一批回答之一。我在iOS 8上进行了测试。我调整了一些东西，包括占位符文本的位置的边界偏移，因为原来的位置太高，太右了(在那个帖子的一个评论中使用了建议)。

我知道有很多简单的解决方案，但我喜欢子类化UITextView的方法，因为它是可重用的，而且我不必在使用它的机制时使类变得混乱。

斯威夫特2.2:

import UIKit

class PlaceholderTextView: UITextView {

    @IBInspectable var placeholderColor: UIColor = UIColor.lightGrayColor()
    @IBInspectable var placeholderText: String = ""

    override var font: UIFont? {
        didSet {
            setNeedsDisplay()
        }
    }

    override var contentInset: UIEdgeInsets {
        didSet {
            setNeedsDisplay()
        }
    }

    override var textAlignment: NSTextAlignment {
        didSet {
            setNeedsDisplay()
        }
    }

    override var text: String? {
        didSet {
            setNeedsDisplay()
        }
    }

    override var attributedText: NSAttributedString? {
        didSet {
            setNeedsDisplay()
        }
    }

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

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

    private func setUp() {
        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(PlaceholderTextView.textChanged(_:)),
                                                         name: UITextViewTextDidChangeNotification, object: self)
    }

    func textChanged(notification: NSNotification) {
        setNeedsDisplay()
    }

    func placeholderRectForBounds(bounds: CGRect) -> CGRect {
        var x = contentInset.left + 4.0
        var y = contentInset.top  + 9.0
        let w = frame.size.width - contentInset.left - contentInset.right - 16.0
        let h = frame.size.height - contentInset.top - contentInset.bottom - 16.0

        if let style = self.typingAttributes[NSParagraphStyleAttributeName] as? NSParagraphStyle {
            x += style.headIndent
            y += style.firstLineHeadIndent
        }
        return CGRect(x: x, y: y, width: w, height: h)
    }

    override func drawRect(rect: CGRect) {
        if text!.isEmpty && !placeholderText.isEmpty {
            let paragraphStyle = NSMutableParagraphStyle()
            paragraphStyle.alignment = textAlignment
            let attributes: [ String: AnyObject ] = [
                NSFontAttributeName : font!,
                NSForegroundColorAttributeName : placeholderColor,
                NSParagraphStyleAttributeName  : paragraphStyle]

            placeholderText.drawInRect(placeholderRectForBounds(bounds), withAttributes: attributes)
        }
        super.drawRect(rect)
    }
}

斯威夫特4.2:

import UIKit

class PlaceholderTextView: UITextView {

    @IBInspectable var placeholderColor: UIColor = UIColor.lightGray
    @IBInspectable var placeholderText: String = ""

    override var font: UIFont? {
        didSet {
            setNeedsDisplay()
        }
    }

    override var contentInset: UIEdgeInsets {
        didSet {
            setNeedsDisplay()
        }
    }

    override var textAlignment: NSTextAlignment {
        didSet {
            setNeedsDisplay()
        }
    }

    override var text: String? {
        didSet {
            setNeedsDisplay()
        }
    }

    override var attributedText: NSAttributedString? {
        didSet {
            setNeedsDisplay()
        }
    }

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

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

    private func setUp() {
        NotificationCenter.default.addObserver(self,
         selector: #selector(self.textChanged(notification:)),
         name: Notification.Name("UITextViewTextDidChangeNotification"),
         object: nil)
    }

    @objc func textChanged(notification: NSNotification) {
        setNeedsDisplay()
    }

    func placeholderRectForBounds(bounds: CGRect) -> CGRect {
        var x = contentInset.left + 4.0
        var y = contentInset.top  + 9.0
        let w = frame.size.width - contentInset.left - contentInset.right - 16.0
        let h = frame.size.height - contentInset.top - contentInset.bottom - 16.0

        if let style = self.typingAttributes[NSAttributedString.Key.paragraphStyle] as? NSParagraphStyle {
            x += style.headIndent
            y += style.firstLineHeadIndent
        }
        return CGRect(x: x, y: y, width: w, height: h)
    }

    override func draw(_ rect: CGRect) {
        if text!.isEmpty && !placeholderText.isEmpty {
            let paragraphStyle = NSMutableParagraphStyle()
            paragraphStyle.alignment = textAlignment
            let attributes: [NSAttributedString.Key: Any] = [
            NSAttributedString.Key(rawValue: NSAttributedString.Key.font.rawValue) : font!,
            NSAttributedString.Key(rawValue: NSAttributedString.Key.foregroundColor.rawValue) : placeholderColor,
            NSAttributedString.Key(rawValue: NSAttributedString.Key.paragraphStyle.rawValue)  : paragraphStyle]

            placeholderText.draw(in: placeholderRectForBounds(bounds: bounds), withAttributes: attributes)
        }
        super.draw(rect)
    }
}

I know there are already a lot of answers to this one, but I didn't really find any of them sufficient (at least in Swift). I needed the "placeholder" functionality of the UITextField in my UITextView (I wanted the exact behavior, including text display attributes, animations, etc, and didn't want to have to maintain this over time). I also wanted a solution that provided the same exact border as a UITextField (not an approximated one that looks sort of like it looks right now, but one that looks exactly like it and will always look exactly like it). So while I was not initially a fan of jamming an extra control into the mix, it seemed that in order to meet my goals I had to use an actual UITextField and let it do the work.

这个解决方案处理定位占位符和保持字体在两个控件之间的同步，以便占位符文本是输入到控件的文本的确切字体和位置(许多其他解决方案没有解决的问题)。

// This class is necessary to support "inset" (required to position placeholder 
// appropriately in TextView)
//
class TextField: UITextField
{
    var inset: UIEdgeInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0);

    override func textRectForBounds(bounds: CGRect) -> CGRect
    {
        return UIEdgeInsetsInsetRect(bounds, inset);
    }

    override func placeholderRectForBounds(bounds: CGRect) -> CGRect
    {
        return UIEdgeInsetsInsetRect(bounds, inset);
    }
}

// This class implements a UITextView that has a UITextField behind it, where the 
// UITextField provides the border and the placeholder text functionality (so that the
// TextView looks and works like a UITextField).
//
class TextView : UITextView, UITextViewDelegate
{
    var textField = TextField();

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

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

        self.delegate = self;

        // Create a background TextField with clear (invisible) text and disabled
        self.textField.borderStyle = UITextBorderStyle.RoundedRect;
        self.textField.textColor = UIColor.clearColor();
        self.textField.userInteractionEnabled = false;

        // Align the background TextView to where text appears in the TextField, so
        // that any placeholder will be in the correct position.
        self.textField.contentVerticalAlignment = UIControlContentVerticalAlignment.Top;
        self.textField.inset = UIEdgeInsets(
            top: self.textContainerInset.top,
            left: self.textContainerInset.left + self.textContainer.lineFragmentPadding,
            bottom: self.textContainerInset.bottom,
            right: self.textContainerInset.right
        );

        // The background TextField should use the same font (for the placeholder)
        self.textField.font = self.font;

        self.addSubview(textField);
        self.sendSubviewToBack(textField);
    }

    convenience init()
    {
        self.init(frame: CGRectZero, textContainer: nil)
    }

    override var font: UIFont?
    {
        didSet
        {
            // Keep the font of the TextView and background textField in sync
            self.textField.font = self.font;
        }
    }

    var placeholder: String? = nil
    {
        didSet
        {
            self.textField.placeholder = self.placeholder;
        }
    }

    override func layoutSubviews()
    {
        super.layoutSubviews()
        // Do not scroll the background textView
        self.textField.frame = CGRectMake(0, self.contentOffset.y, self.frame.width, self.frame.height);
    }

    // UITextViewDelegate - Note: If you replace delegate, your delegate must call this
    func scrollViewDidScroll(scrollView: UIScrollView)
    {
        // Do not scroll the background textView
        self.textField.frame = CGRectMake(0, self.contentOffset.y, self.frame.width, self.frame.height);
    }

    // UITextViewDelegate - Note: If you replace delegate, your delegate must call this
    func textViewDidChange(textView: UITextView)
    {
        // Updating the text in the background textView will cause the placeholder to 
        // appear/disappear (including any animations of that behavior - since the
        // textView is doing this itself).
        self.textField.text = self.text;
    }
}

简单的方法，使用以下UITextViewDelegate方法在UITextView中创建占位符文本:

- (void)textViewDidBeginEditing:(UITextView *)textView
{
    if ([textView.text isEqualToString:@"placeholder text here..."]) {
         textView.text = @"";
         textView.textColor = [UIColor blackColor]; //optional
    }
    [textView becomeFirstResponder];
}

- (void)textViewDidEndEditing:(UITextView *)textView
{
    if ([textView.text isEqualToString:@""]) {
        textView.text = @"placeholder text here...";
        textView.textColor = [UIColor lightGrayColor]; //optional
    }
    [textView resignFirstResponder];
}

只需要记住在创建时使用准确的文本设置myUITextView即可。

UITextView *myUITextView = [[UITextView alloc] init];
myUITextView.delegate = self;
myUITextView.text = @"placeholder text here...";
myUITextView.textColor = [UIColor lightGrayColor]; //optional

在包含这些方法之前，让父类成为一个UITextViewDelegate。

@interface MyClass () <UITextViewDelegate>
@end

Swift 3.1代码

func textViewDidBeginEditing(_ textView: UITextView) 
{
    if (textView.text == "placeholder text here..." && textView.textColor == .lightGray)
    {
        textView.text = ""
        textView.textColor = .black
    }
    textView.becomeFirstResponder() //Optional
}

func textViewDidEndEditing(_ textView: UITextView)
{
    if (textView.text == "")
    {
        textView.text = "placeholder text here..."
        textView.textColor = .lightGray
    }
    textView.resignFirstResponder()
}

只需要记住在创建时使用准确的文本设置myUITextView即可。

 let myUITextView = UITextView.init()
 myUITextView.delegate = self
 myUITextView.text = "placeholder text here..."
 myUITextView.textColor = .lightGray

在包含这些方法之前，让父类成为一个UITextViewDelegate。

class MyClass: UITextViewDelegate
{

}

在h课上

@interface RateCommentViewController : UIViewController<UITextViewDelegate>{IBoutlet UITextview *commentTxtView;}

在。m类

- (void)viewDidLoad{      
    commentTxtView.text = @"Comment";
    commentTxtView.textColor = [UIColor lightGrayColor];
    commentTxtView.delegate = self;
}

- (BOOL) textViewShouldBeginEditing:(UITextView *)textView
{
    commentTxtView.text = @"";
    commentTxtView.textColor = [UIColor blackColor];
    return YES;
}

-(void) textViewDidChange:(UITextView *)textView
{
    if(commentTxtView.text.length == 0){
        commentTxtView.textColor = [UIColor lightGrayColor];
        commentTxtView.text = @"Comment";
        [commentTxtView resignFirstResponder];
    }
}