如果有人需要Swift的解决方案:

添加UITextViewDelegate到类中

var placeHolderText = "Placeholder Text..."

override func viewDidLoad() {
    super.viewDidLoad()
    textView.delegate = self
}

func textViewShouldBeginEditing(textView: UITextView) -> Bool {

    self.textView.textColor = .black

    if(self.textView.text == placeHolderText) {
        self.textView.text = ""
    }

    return true
}

func textViewDidEndEditing(textView: UITextView) {
    if(textView.text == "") {
        self.textView.text = placeHolderText
        self.textView.textColor = .lightGray
    }
}

override func viewWillAppear(animated: Bool) {

    if(currentQuestion.answerDisplayValue == "") {
        self.textView.text = placeHolderText
        self.textView.textColor = .lightGray
    } else {
        self.textView.text = "xxx" // load default text / or stored 
        self.textView.textColor = .black
    }
}

嗨，你可以使用IQTextView可用的IQKeyboard管理器，这是简单的使用和集成只是设置类你的textview到IQTextView，你可以使用它的属性设置占位符标签与你想要的颜色。 您可以从IQKeyboardManager下载该库

或者你也可以从cocoapods上安装。

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;
}

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];
    }

}

你可以在textview上设置一个标签。

MyUITextView.h

@interface MyUITextView : UITextView {
    UILabel* _placeholderLabel;
}

@property(nonatomic, assign)NSString *placeholder;

MyUITextView.m

@implementation MyUITextView

- (id)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        // Create placeholder
        viewFrame = CGRectMake(0, 0, frame.size.width, 15);
        _placeholderLabel = [[UILabel alloc] initWithFrame:viewFrame];
        _placeholderLabel.textColor = [UIColor lightGrayColor];
        [self addSubview:_placeholderLabel];

        // Add text changed notification 
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
    }
    return self;
}

- (void)setPlaceholder:(NSString *)placeholder {
    _placeholderLabel.text = placeholder;
}

- (NSString*)placeholder {
    return _placeholderLabel.text;
}

#pragma mark UITextViewTextDidChangeNotification

- (void)textChanged:(NSNotification *)notification {
    _placeholderLabel.hidden = ([self.text lenght] == 0);
}

@end

After looking through (and trying out) most of the proposed solutions to this seemingly obvious - but missing - feature of UITextView, the 'best' closest I found was that from BobDickinson. But I didnt like having to resort to a whole new subclass [I prefer drop-in categories for such simple functional additions], nor that it intercepted UITextViewDelegate methods, which is probably going to mess up your existing UITextView handling code. So here's my take on a drop-in category that'll work on any existing UITextView instance...

#import <objc/runtime.h>

// Private subclass needed to override placeholderRectForBounds: to correctly position placeholder
@interface _TextField : UITextField
@property UIEdgeInsets insets;
@end
@implementation _TextField
- (CGRect)placeholderRectForBounds:(CGRect)bounds
{
    CGRect rect = [super placeholderRectForBounds:bounds];
    return UIEdgeInsetsInsetRect(rect, _insets);
}
@end

@implementation UITextView (Placeholder)

static const void *KEY;

- (void)setPlaceholder:(NSString *)placeholder
{
    _TextField *textField = objc_getAssociatedObject(self, &KEY);
    if (!textField) {
        textField = [_TextField.alloc initWithFrame:self.bounds];
        textField.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
        textField.userInteractionEnabled = NO;
        textField.font = self.font;

        textField.contentVerticalAlignment = UIControlContentVerticalAlignmentTop;
        textField.insets = UIEdgeInsetsMake(self.textContainerInset.top,
                                            self.textContainerInset.left + self.textContainer.lineFragmentPadding,
                                            self.textContainerInset.bottom,
                                            self.textContainerInset.right);
        [self addSubview:textField];
        [self sendSubviewToBack:textField];

        objc_setAssociatedObject(self, &KEY, textField, OBJC_ASSOCIATION_RETAIN);

        [NSNotificationCenter.defaultCenter addObserver:self selector:@selector(updatePlaceholder:) name:UITextViewTextDidChangeNotification object:nil];
    }
    textField.placeholder = placeholder;
}

- (NSString*)placeholder
{
    UITextField *textField = objc_getAssociatedObject(self, &KEY);
    return textField.placeholder;
}

- (void)updatePlaceholder:(NSNotification *)notification
{
    UITextField *textField = objc_getAssociatedObject(self, &KEY);
    textField.font = self.font;
    [textField setAlpha:self.text.length? 0 : 1];
}

@end

它使用简单，只是显而易见的

UITextView *myTextView = UITextView.new;
...
myTextView.placeholder = @"enter text here";

它通过添加一个UITextField -在正确的位置-在你的UITextView后面，并利用它的占位符代替(因此你不必担心得到正确的颜色等)，然后监听通知，每当你的UITextView被改变显示/隐藏这个UITextField(因此它不会干扰你现有的UITextViewDelegate调用)。这里面没有什么神奇的数字……: -)

objc_setAssociatedObject()/objc_getAssociatedObject()是为了避免必须子类化UITextView。[不幸的是，要正确地定位UITextField，有必要引入一个'private'子类，以覆盖placeholderRectForBounds:]

改编自BobDickinson的斯威夫特回答。