- (BOOL) textViewShouldBeginEditing:(UITextView *)textView
{
    //NSLog(@"textViewShouldBeginEditing");
    if( [tvComment.text isEqualToString:@"Comment"] && [tvComment.textColor isEqual:[UIColor lightGrayColor]] ){
        tvComment.text = @"";
        tvComment.textColor = [UIColor blackColor];
    }
    return YES;
}

- (void)keyboardWillBeHidden:(NSNotification*)aNotification{
    //NSLog(@"keyboardWillBeHidden");

    //Manage comment field placeholdertext
    if(tvComment.text.length == 0){
        tvComment.textColor = [UIColor lightGrayColor];
        tvComment.text = @"Comment";
    }
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    tvComment.textColor = [UIColor lightGrayColor];
}

TVComment是包含问题中的textView的属性。这样就可以了。

我找到了一个很容易模仿占位符的方法

在NIB或代码设置你的textView的textColor为lightGrayColor(大多数时候) 确保你的textView的委托链接到文件的所有者和实现UITextViewDelegate在你的头文件 将文本视图的默认文本设置为(例如:"Foobar placeholder") 实现:(BOOL) textViewShouldBeginEditing:(UITextView *)textView

编辑:

Changed if statements to compare tags rather than text. If the user deleted their text it was possible to also accidentally delete a portion of the place holder @"Foobar placeholder".This meant if the user re-entered the textView the following delegate method, -(BOOL) textViewShouldBeginEditing:(UITextView *) textView, it would not work as expected. I tried comparing by the color of the text in the if statement but found that light grey color set in interface builder is not the same as light grey color set in code with [UIColor lightGreyColor]

- (BOOL) textViewShouldBeginEditing:(UITextView *)textView
{
    if(textView.tag == 0) {
        textView.text = @"";
        textView.textColor = [UIColor blackColor];
        textView.tag = 1;
    }
    return YES;
}

当键盘返回并且[textView length] == 0时，也可以重置占位符文本

编辑:

只是为了让最后一部分更清楚——下面是如何将占位符文本设置回去:

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

我能够做添加一个“占位符”到UITextView与很多少的代码。这就是我所做的:

UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(60, 800, 200, 60)];
textView.text = @"Write characters here...";
textView.textColor=[UIColor grayColor];
textView.font = [UIFont fontWithName:@"Hevlatica" size:15];
textView.delegate=self;

我猜这不是一个真正的占位符，因为你必须在写之前删除文本，但如果你想要一些更简单的东西，它可能会有帮助。

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;
    }
}

斯威夫特3.1

在尝试了所有快速的答案之后，这个答案将为我节省3个小时的研究时间。希望这能有所帮助。

确保你的textField(不管你有什么自定义名称)指向它在Storyboard中的委托，并且有一个@IBOutlet和你的customtextfield 将以下内容添加到viewDidLoad()中，加载视图时会出现:

告诉我什么看起来是占位符:

yourCustomTextField = "Start typing..." 
yourCustomTextField.textColor = .lightGray

在viewDidLoad外部但在同一个类内部添加以下声明:UIViewController, UITextViewDelegate, UINavigationControllerDelegate

这段代码将使yourCustomTextField在输入textField时消失:

func textViewDidBeginEditing (_ textView: UITextView) { 

    if (textView.text == "Start typing...") {

        textView.text = ""
        textView.textColor = .black
    }

    textView.becomeFirstResponder()
}

func textViewDidEndEditing(_ textView: UITextView) {
    if (textView.text == "") {

        textView.text = "Start typing..."
        textView.textColor = .lightGray
    }

    textView.resignFirstResponder()
}

基于这里已经给出的一些很好的建议，我能够将以下轻量级的、与接口生成器兼容的UITextView子类组合在一起，它是:

包括可配置的占位符文本，样式就像UITextField一样。 不需要任何额外的子视图或约束。 不需要来自ViewController的任何委托或其他行为。 不需要任何通知。 保持该文本与查看字段的文本属性的任何外部类完全分离。

欢迎提出改进建议。

编辑1:更新为重置占位符格式，如果实际文本以编程方式设置。

编辑2:现在可以以编程方式检索占位符文本颜色。

斯威夫特v5:

import UIKit
@IBDesignable class TextViewWithPlaceholder: UITextView {
    
    override var text: String! { // Ensures that the placeholder text is never returned as the field's text
        get {
            if showingPlaceholder {
                return "" // When showing the placeholder, there's no real text to return
            } else { return super.text }
        }
        set {
            if showingPlaceholder {
                removePlaceholderFormatting() // If the placeholder text is what's being changed, it's no longer the placeholder
            }
            super.text = newValue
        }
    }
    @IBInspectable var placeholderText: String = ""
    @IBInspectable var placeholderTextColor: UIColor = .placeholderText
    private var showingPlaceholder: Bool = true // Keeps track of whether the field is currently showing a placeholder
    
    override func didMoveToWindow() {
        super.didMoveToWindow()
        if text.isEmpty {
            showPlaceholderText() // Load up the placeholder text when first appearing, but not if coming back to a view where text was already entered
        }
    }
    
    override public func becomeFirstResponder() -> Bool {
        
        // If the current text is the placeholder, remove it
        if showingPlaceholder {
            text = nil
            removePlaceholderFormatting()
        }
        return super.becomeFirstResponder()
    }
    
    override public func resignFirstResponder() -> Bool {
        
        // If there's no text, put the placeholder back
        if text.isEmpty {
            showPlaceholderText()
        }
        return super.resignFirstResponder()
    }
    
    private func showPlaceholderText() {
        
        text = placeholderText
        showingPlaceholder = true
        textColor = placeholderTextColor
    }
    
    private func removePlaceholderFormatting() {
        
        showingPlaceholder = false
        textColor = nil // Put the text back to the default, unmodified color
    }
}