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
{

}

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;
}

在swift 5。工作很好。

class BaseTextView: UITextView {

    // MARK: - Views
    private var placeholderLabel: UIlabel!

    // MARK: - Init
    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        setupUI()
        startupSetup()
    }

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

    deinit {
        NotificationCenter.default.removeObserver(self)
    }    
}

// MARK: - Setup UI
private extension BaseTextView {
    func setupUI() {
        addPlaceholderLabel()

        textColor = .textColor
    }

    func addPlaceholderLabel() {
        placeholderLabel = BaseLabel(frame: .zero)
        placeholderLabel.translatesAutoresizingMaskIntoConstraints = false
        insertSubview(placeholderLabel, at: 0)

        placeholderLabel.alpha = 0
        placeholderLabel.numberOfLines = 0
        placeholderLabel.backgroundColor = .clear
        placeholderLabel.textColor = .lightTextColor
        placeholderLabel.lineBreakMode = .byWordWrapping
        placeholderLabel.isUserInteractionEnabled = false
        placeholderLabel.font = UIFont.openSansSemibold.withSize(12)

        placeholderLabel.topAnchor.constraint(equalTo: topAnchor, constant: 8).isActive = true
        placeholderLabel.leftAnchor.constraint(equalTo: leftAnchor, constant: 5).isActive = true
        placeholderLabel.rightAnchor.constraint(lessThanOrEqualTo: rightAnchor, constant: -8).isActive = true
        placeholderLabel.bottomAnchor.constraint(lessThanOrEqualTo: bottomAnchor, constant: -8).isActive = true
    }
}

// MARK: - Startup
private extension BaseTextView {
    func startupSetup() {
        addObservers()
        textChanged(nil)
        font = UIFont.openSansSemibold.withSize(12)
    }    

    func addObservers() {
        NotificationCenter.default.addObserver(self, selector: #selector(textChanged(_:)), name: UITextView.textDidChangeNotification, object: nil)
    }
}

// MARK: - Actions
private extension BaseTextView {
    @objc func textChanged(_ sender: Notification?) {
        UIView.animate(withDuration: 0.2) {
            self.placeholderLabel.alpha = self.text.count == 0 ? 1 : 0
        }    
    }
}

// MARK: - Public methods
extension BaseTextView {
    public func setPlaceholder(_ placeholder: String) {
        placeholderLabel.text = placeholder
    }
}

我遵循了这个链接的代码。只有7个简单的步骤。它添加了一个UILabel的textView和隐藏/显示标签时，文本输入或从textView通过textView的textViewDidChangeSelection(_ textView: UITextView)委托方法。我将步骤放在代码上方的注释中。

// 1. make sure to include the UITextViewDelegate
class YourClass: UITextViewDelegate {

    @IBOutlet weak var textView : UITextView!

    // 2. create placeholder textLabel
    let placeHolderTextLabel: UILabel = {
        let placeholderLabel = UILabel()
        placeholderLabel.text = "Placeholder text..."
        placeholderLabel.sizeToFit()
        placeholderLabel.textColor = UIColor.lightGray
        return placeholderLabel
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        // 3. set textView delegate
        textView.delegate = self

        configurePlaceholderTextLabel()
    }


    func configurePlaceholderTextLabel() {

        // 4. add placeholder label to textView, set it's frame and font
        textView.addSubview(placeHolderTextLabel)
        placeHolderTextLabel.frame.origin = CGPoint(x: 5, y: (textView.font?.pointSize)! / 2)
        placeHolderTextLabel.font = UIFont.systemFont(ofSize: (textView.font?.pointSize)!)

        // 5. decide wether the placeHolderTextLabel is hidden or not depending on if there is or isn't text inside the textView
        placeHolderTextLabel.isHidden = !textView.text.isEmpty

    }

    // 6. implement textView delegate method to update the placeHolderTextLabel when the text is changed
    func textViewDidChangeSelection(_ textView: UITextView) {

        // 7. decide wether the placeHolderTextLabel is hidden or not depending on if there is or isn't text inside the textView when text in textView is changed
        placeHolderTextLabel.isHidden = !textView.text.isEmpty
    }

}

好吧，我的阴沟有点不同 我创建了一个小班来为你做这件事。

TextViewShader。m文件

#import "TextViewShader.h"

@implementation TextViewShader
-(id)initWithShadedTextView:(NSString *)text textViewToShade:(UITextView *)textview {
    self = [super initWithFrame:textview.frame];
    if (self) {
        if (shadeLabel==nil)
        {
            shadeLabel= [[UILabel alloc]initWithFrame:CGRectMake(10, 0, textview.frame.size.width, 30)];


    }
    shadeLabel.text =text;// @"Enter Your Support Request";
    shadeLabel.textColor = [UIColor lightGrayColor];
    [textview setDelegate: self];
    [textview addSubview:shadeLabel];
}
return self;
}

-(void)textViewDidChange:(UITextView *)textView{
        if (textView.text.length==0)
        {
            shadeLabel.hidden=false; 
        }
        else
        {
            shadeLabel.hidden=true;
        }

}

@end

TextViewShader.h文件

#import <UIKit/UIKit.h>

@interface TextViewShader : UIView<UITextViewDelegate>{
    UILabel *shadeLabel;

}
-(id)initWithShadedTextView:(NSString *)text textViewToShade:(UITextView *)textview ;
@end

这是简单的一行代码使用(不要忘记添加#import "TextViewShader.h")

 TextViewShader* shader = [[TextViewShader alloc]initWithShadedTextView:@"Enter Your Support Request" textViewToShade: youruitextviewToshade];

玩得开心!

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。