你也可以创建一个新的类TextViewWithPlaceholder作为UITextView的子类。

(这段代码有点粗糙——但我认为它在正确的轨道上。)

@interface TextViewWithPlaceholder : UITextView
{

    NSString *placeholderText;  // make a property
    UIColor *placeholderColor;  // make a property
    UIColor *normalTextColor;   // cache text color here whenever you switch to the placeholderColor
}

- (void) setTextColor: (UIColor*) color
{
   normalTextColor = color;
   [super setTextColor: color];
}

- (void) updateForTextChange
{
    if ([self.text length] == 0)
    { 
        normalTextColor = self.textColor;
        self.textColor = placeholderColor;
        self.text = placeholderText;
    }
    else
    {
        self.textColor = normalTextColor;
    }

}

在委托中，添加以下内容:

- (void)textViewDidChange:(UITextView *)textView
{
    if ([textView respondsToSelector: @selector(updateForTextChange)])
    {
        [textView updateForTextChange];
    }

}

我是这样做的:

UITextView2.h

#import <UIKit/UIKit.h>

@interface UITextView2 : UITextView <UITextViewDelegate> {
 NSString *placeholder;
 UIColor *placeholderColor;
}

@property(nonatomic, retain) NSString *placeholder;
@property(nonatomic, retain) UIColor *placeholderColor;

-(void)textChanged:(NSNotification*)notif;

@end

UITextView2.m

@implementation UITextView2

@synthesize placeholder, placeholderColor;

- (id)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        [self setPlaceholder:@""];
        [self setPlaceholderColor:[UIColor lightGrayColor]];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
    }
    return self;
}

-(void)textChanged:(NSNotification*)notif {
    if ([[self placeholder] length]==0)
        return;
    if ([[self text] length]==0) {
        [[self viewWithTag:999] setAlpha:1];
    } else {
        [[self viewWithTag:999] setAlpha:0];
    }

}

- (void)drawRect:(CGRect)rect {
    if ([[self placeholder] length]>0) {
        UILabel *l = [[UILabel alloc] initWithFrame:CGRectMake(8, 8, 0, 0)];
        [l setFont:self.font];
        [l setTextColor:self.placeholderColor];
        [l setText:self.placeholder];
        [l setAlpha:0];
        [l setTag:999];
        [self addSubview:l];
        [l sizeToFit];
        [self sendSubviewToBack:l];
        [l release];
    }
    if ([[self text] length]==0 && [[self placeholder] length]>0) {
        [[self viewWithTag:999] setAlpha:1];
    }
    [super drawRect:rect];
}

- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
    [super dealloc];
}


@end

这是我的版本的UITextView与占位符支持。斯威夫特4.2 https://gist.github.com/hlung/c5dda3a0c2087e5ae6c1fce8822c4713

一个支持占位符文本的UITextView子类。它使用另一个 UILabel显示占位符，当文本为空时显示。

在看完所有答案后，我意识到我需要一些简单的，同时可重用的东西，这样我就可以在我的项目中为所有uitextview添加相同的功能。最后我得到了以下代码:

extension UITextView {

// MARK: TextView PlaceHolderLabel Setup

func createPlaceHolderLabel(with text: String) {
    let lbl = UILabel()
    self.addSubview(lbl)

// Add your constraints here

    lbl.text = text
    lbl.textColor = .lightGray
}

// My Textview contains only one UILabel, and for my use case the below code works, tweak it according to your use case

// Lastly two methods to toggle between show and hide the placeholder label

func hidePlaceHolderLabel() {
    guard let lbl = self.subviews.first(where: { $0 is UILabel }) else { return }
    lbl.isHidden = true
}

func showPlaceHolderLabel() {
    guard let lbl = self.subviews.first(where: { $0 is UILabel }) else { return }
    lbl.isHidden = false
}

}

当UILabel作为子视图添加到UITextView时，textView游标位置和UILabel位置将不匹配，因此在占位符文本之前留下一个空间

class ViewController: UIViewController, UITextViewDelegate {
    var textView: UITextView!

override func viewDidLoad() {
    super.viewDidLoad()
    view.addSubview(textView)
    // Also setup textView constraints as per your need
    // Add placeholder to your textView
    // Leave one space before placeholder string
    textView.createPlaceHolderLabel(with: " Address")
    textView.delegate = self
}

然后在textViewdidChange方法中添加以下代码

func textViewDidChange(_ textView: UITextView) {
    if textView.text.isEmpty {
        textView.showPlaceHolderLabel()
    } else {
        textView.hidePlaceHolderLabel()
    }
}

它可以在所有uitextview中重用。

简单地创建UITextView的@IBDesignable子类:

@IBDesignable class AttributedTextView: UITextView {

    private let placeholderLabel = UILabel()

    @IBInspectable var placeholder: String = "" {

        didSet {

            setupPlaceholderLabelIfNeeded()
            textViewDidChange()
        }
    }

    override var text: String! {

        didSet {
            textViewDidChange()
        }
    }

    //MARK: - Initialization

    override func awakeFromNib() {
        super.awakeFromNib()

        setupPlaceholderLabelIfNeeded()
        NotificationCenter.default.addObserver(self, selector: #selector(textViewDidChange), name: .UITextViewTextDidChange, object: nil)
    }

    //MARK: - Deinitialization

    deinit {
        NotificationCenter.default.removeObserver(self)
    }

    //MARK: - Internal

    func textViewDidChange() {

        placeholderLabel.isHidden = !text.isEmpty
        layoutIfNeeded()
    }

    //MARK: - Private

    private func setupPlaceholderLabelIfNeeded() {

        placeholderLabel.removeFromSuperview()
        placeholderLabel.frame = CGRect(x: 0, y: 8, width: frame.size.width, height: 0)
        placeholderLabel.textColor = UIColor.lightGray
        placeholderLabel.text = placeholder

        placeholderLabel.sizeToFit()

        insertSubview(placeholderLabel, at: 0)
    }
}

然后在标识检查器中设置占位符:

我做了我自己版本的UITextView的子类。我喜欢Sam Soffes使用通知的想法，但我不喜欢drawRect: overwrite。对我来说太过分了。我认为我做了一个非常干净的实现。

你可以看看我的子类。还包括一个演示项目。