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;
   }
}

我对bcd的解决方案做了一些小修改，以允许从Xib文件初始化、文本包装和保持背景颜色。希望它能为其他人省去麻烦。

UIPlaceHolderTextView.h:

#import <Foundation/Foundation.h>
IB_DESIGNABLE
@interface UIPlaceHolderTextView : UITextView

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

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

@end

UIPlaceHolderTextView.m:

#import "UIPlaceHolderTextView.h"

@interface UIPlaceHolderTextView ()

@property (nonatomic, retain) UILabel *placeHolderLabel;

@end

@implementation UIPlaceHolderTextView

CGFloat const UI_PLACEHOLDER_TEXT_CHANGED_ANIMATION_DURATION = 0.25;

- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
#if __has_feature(objc_arc)
#else
    [_placeHolderLabel release]; _placeHolderLabel = nil;
    [_placeholderColor release]; _placeholderColor = nil;
    [_placeholder release]; _placeholder = nil;
    [super dealloc];
#endif
}

- (void)awakeFromNib
{
    [super awakeFromNib];

    // Use Interface Builder User Defined Runtime Attributes to set
    // placeholder and placeholderColor in Interface Builder.
    if (!self.placeholder) {
        [self setPlaceholder:@""];
    }

    if (!self.placeholderColor) {
        [self setPlaceholderColor:[UIColor lightGrayColor]];
    }

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}

- (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 *)notification
{
    if([[self placeholder] length] == 0)
    {
        return;
    }

    [UIView animateWithDuration:UI_PLACEHOLDER_TEXT_CHANGED_ANIMATION_DURATION animations:^{
    if([[self text] length] == 0)
    {
        [[self viewWithTag:999] setAlpha:1];
    }
    else
    {
        [[self viewWithTag:999] setAlpha:0];
    }
    }];
}

- (void)setText:(NSString *)text {
    [super setText:text];
    [self textChanged:nil];
}

- (void)drawRect:(CGRect)rect
{
    if( [[self placeholder] length] > 0 )
    {
        if (_placeHolderLabel == nil )
        {
            _placeHolderLabel = [[UILabel alloc] initWithFrame:CGRectMake(8,8,self.bounds.size.width - 16,0)];
            _placeHolderLabel.lineBreakMode = NSLineBreakByWordWrapping;
            _placeHolderLabel.numberOfLines = 0;
            _placeHolderLabel.font = self.font;
            _placeHolderLabel.backgroundColor = [UIColor clearColor];
            _placeHolderLabel.textColor = self.placeholderColor;
            _placeHolderLabel.alpha = 0;
            _placeHolderLabel.tag = 999;
            [self addSubview:_placeHolderLabel];
        }

        _placeHolderLabel.text = self.placeholder;
        [_placeHolderLabel sizeToFit];
        [self sendSubviewToBack:_placeHolderLabel];
    }

    if( [[self text] length] == 0 && [[self placeholder] length] > 0 )
    {
        [[self viewWithTag:999] setAlpha:1];
    }

    [super drawRect:rect];
}

@end

如果你正在寻找一个简单的方法来实现这一点，试试我的方法:

- (BOOL)textViewShouldBeginEditing:(UITextView *)textView
{
    if ([[textView text] isEqualToString:PLACE_HOLDER_TEXT]) {
          textView.text = @"";
          textView.textColor = [UIColor blackColor];
    }

    return YES;
}

-(BOOL)textViewShouldEndEditing:(UITextView *)textView
{
    if ([[textView text] length] == 0) {
        textView.text = PLACE_HOLDER_TEXT;
        textView.textColor = [UIColor lightGrayColor];
    }
    return YES;
}

是的，就是它PLACE_HOLDER_TEXT是一个NSString包含你的占位符

我刚刚发现，在iOS 10中，你现在可以将UITextView转换为方法的UITextField，并在方法中设置占位符。刚试过，它不需要子类化UITextView就能工作。

下面是一个对我有用的例子:

-(void)customizeTextField:(UITextField *)textField placeholder:(NSString *)pText withColor:(UIColor *)pTextColor{

        textField.attributedPlaceholder = [[NSAttributedString alloc]
                                          initWithString:pText
                                          attributes:@{NSForegroundColorAttributeName:pTextColor}];
    }

为了将它用于UITextView，你只需要将它传递给方法，使用像这样的类型转换:

[self customizeTextField:(UITextField*)_myTextView placeholder:@"Placeholder" withColor:[UIColor blackColor]];

注:经过测试，我发现这个解决方案在iOS9上也很好。但是会在iOS8.x上导致崩溃

我建议使用SZTextView。

https://github.com/glaszig/SZTextView

从storyboard中添加默认的UITextView，然后将其自定义类更改为SZTextView，如下所示

然后您将在属性检查器中看到两个新选项

在UITextView中创建占位符是不可能的，但是你可以通过这个生成类似占位符的效果。

  - (void)viewDidLoad{      
              commentTxtView.text = @"Comment";
              commentTxtView.textColor = [UIColor lightGrayColor];
              commentTxtView.delegate = self;

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

     -(void) textViewDidChange:(UITextView *)textView
     {

    if(commentTxtView.text.length == 0){
        commentTxtView.textColor = [UIColor lightGrayColor];
        commentTxtView.text = @"Comment";
        [commentTxtView resignFirstResponder];
    }
    }

或者你可以添加标签在textview就像

       lbl = [[UILabel alloc] initWithFrame:CGRectMake(10.0, 0.0,textView.frame.size.width - 10.0, 34.0)];


[lbl setText:kDescriptionPlaceholder];
[lbl setBackgroundColor:[UIColor clearColor]];
[lbl setTextColor:[UIColor lightGrayColor]];
textView.delegate = self;

[textView addSubview:lbl];

并设置

- (void)textViewDidEndEditing:(UITextView *)theTextView
{
     if (![textView hasText]) {
     lbl.hidden = NO;
}
}

- (void) textViewDidChange:(UITextView *)textView
{
    if(![textView hasText]) {
      lbl.hidden = NO;
}
else{
    lbl.hidden = YES;
 }  
}