这完美地模仿了UITextField的占位符，其中占位符文本一直保留到您实际键入一些内容为止。

private let placeholder = "Type here"

@IBOutlet weak var textView: UITextView! {
    didSet {
        textView.textColor = UIColor.lightGray
        textView.text = placeholder
        textView.selectedRange = NSRange(location: 0, length: 0)
    }
}

extension ViewController: UITextViewDelegate {

    func textViewDidChangeSelection(_ textView: UITextView) {
        // Move cursor to beginning on first tap
        if textView.text == placeholder {
            textView.selectedRange = NSRange(location: 0, length: 0)
        }
    }

    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        if textView.text == placeholder && !text.isEmpty {
            textView.text = nil
            textView.textColor = UIColor.black
            textView.selectedRange = NSRange(location: 0, length: 0)
        }
        return true
    }

    func textViewDidChange(_ textView: UITextView) {
        if textView.text.isEmpty {
            textView.textColor = UIColor.lightGray
            textView.text = placeholder
        }
    }
}

这完美地模仿了UITextField的占位符，其中占位符文本一直保留到您实际键入一些内容为止。

private let placeholder = "Type here"

@IBOutlet weak var textView: UITextView! {
    didSet {
        textView.textColor = UIColor.lightGray
        textView.text = placeholder
        textView.selectedRange = NSRange(location: 0, length: 0)
    }
}

extension ViewController: UITextViewDelegate {

    func textViewDidChangeSelection(_ textView: UITextView) {
        // Move cursor to beginning on first tap
        if textView.text == placeholder {
            textView.selectedRange = NSRange(location: 0, length: 0)
        }
    }

    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        if textView.text == placeholder && !text.isEmpty {
            textView.text = nil
            textView.textColor = UIColor.black
            textView.selectedRange = NSRange(location: 0, length: 0)
        }
        return true
    }

    func textViewDidChange(_ textView: UITextView) {
        if textView.text.isEmpty {
            textView.textColor = UIColor.lightGray
            textView.text = placeholder
        }
    }
}

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];
    }

}

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()
}

下面是swift 3.1的代码

原始代码由杰森乔治在第一个答案。

不要忘记设置你的自定义类的TextView在接口生成器UIPlaceHolderTextView，然后设置占位符和占位符属性。

import UIKit

@IBDesignable
class UIPlaceHolderTextView: UITextView {

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

private let uiPlaceholderTextChangedAnimationDuration: Double = 0.05
private let defaultTagValue = 999

private var placeHolderLabel: UILabel?

override func awakeFromNib() {
    super.awakeFromNib()
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(textChanged),
        name: NSNotification.Name.UITextViewTextDidChange,
        object: nil
    )
}

override init(frame: CGRect, textContainer: NSTextContainer?) {
    super.init(frame: frame, textContainer: textContainer)
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(textChanged),
        name: NSNotification.Name.UITextViewTextDidChange,
        object: nil
    )
}

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(textChanged),
        name: NSNotification.Name.UITextViewTextDidChange,
        object: nil
    )
}

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

@objc private func textChanged() {
    guard !placeholder.isEmpty else {
        return
    }
    UIView.animate(withDuration: uiPlaceholderTextChangedAnimationDuration) {
        if self.text.isEmpty {
            self.viewWithTag(self.defaultTagValue)?.alpha = CGFloat(1.0)
        }
        else {
            self.viewWithTag(self.defaultTagValue)?.alpha = CGFloat(0.0)
        }
    }
}

override var text: String! {
    didSet{
        super.text = text
        textChanged()
    }
}

override func draw(_ rect: CGRect) {
    if !placeholder.isEmpty {
        if placeHolderLabel == nil {
            placeHolderLabel = UILabel.init(frame: CGRect(x: 0, y: 8, width: bounds.size.width - 16, height: 0))
            placeHolderLabel!.lineBreakMode = .byWordWrapping
            placeHolderLabel!.numberOfLines = 0
            placeHolderLabel!.font = font
            placeHolderLabel!.backgroundColor = UIColor.clear
            placeHolderLabel!.textColor = placeholderColor
            placeHolderLabel!.alpha = 0
            placeHolderLabel!.tag = defaultTagValue
            self.addSubview(placeHolderLabel!)
        }

        placeHolderLabel!.text = placeholder
        placeHolderLabel!.sizeToFit()
        self.sendSubview(toBack: placeHolderLabel!)

        if text.isEmpty && !placeholder.isEmpty {
            viewWithTag(defaultTagValue)?.alpha = 1.0
        }
    }

    super.draw(rect)
}
}

我创建了一个实例变量来检查是否显示占位符:

BOOL showPlaceHolder;
UITextView * textView; // and also the textView

在viewDidLoad上设置:

[self setPlaceHolder]; 

下面是它的作用:

- (void)setPlaceholder
{
    textView.text = NSLocalizedString(@"Type your question here", @"placeholder");
    textView.textColor = [UIColor lightGrayColor];
    self.showPlaceHolder = YES; //we save the state so it won't disappear in case you want to re-edit it
}

我还创建了一个按钮来退出键盘。您不必这样做，但这里很酷的事情是，如果没有输入任何内容，占位符将再次显示

- (void)textViewDidBeginEditing:(UITextView *)txtView 
{
    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleDone target:self action:@selector(resignKeyboard)];
    if (self.showPlaceHolder == YES) 
    {
        textView.textColor = [UIColor blackColor];
        textView.text = @"";
        self.showPlaceHolder = NO;
    }
}

- (void)resignKeyboard 
{
    [textView resignFirstResponder];
    //here if you created a button like I did to resign the keyboard, you should hide it
    if (textView.text.length == 0) {
        [self setPlaceholder];
    }       
}