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!

    - (void)textViewDidChange:(UITextView *)textView
{
    placeholderLabel.hidden = YES;
}

在textview上放一个标签。

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;
   }
}

- (void)viewDidLoad {
    [super viewDidLoad];

    self.textViewEmpty = YES;

    // Text view
    self.textView = [[UITextView alloc] init];
    self.textView.translatesAutoresizingMaskIntoConstraints = NO; // For AutoLayout
    self.textView.delegate = self;
    self.textView.textColor = [UIColor grayColor];
    self.textView.text = @"Placeholder";

    // Add subview and constraints
}

#pragma mark - UITextView

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

    return YES;
}

- (void)textViewDidChange:(UITextView *)textView {
    if (textView.text.length > 0) {
        self.textViewEmpty = NO;
    } else {
        self.textViewEmpty = YES;
    }
}

- (BOOL)textViewShouldEndEditing:(UITextView *)textView {
    if (self.isTextViewEmpty) {
        textView.textColor = [UIColor lightGrayColor];
        textView.text = placeholderText;
    }

    return YES;
}

让我们简单点

创建一个UILabel并把它放在你的文本视图上(给文本作为占位符-设置颜色为灰色-你可以在你的xib中做这一切) 现在在头文件中声明UILabel和textviewDelegate 现在你可以简单地隐藏标签，当你点击textview

完整代码如下

头

@interface ViewController :UIViewController<UITextViewDelegate>{
 }
   @property (nonatomic,strong) IBOutlet UILabel *PlceHolder_label;
   @property (nonatomic,strong) IBOutlet UITextView *TextView;

@end

实现

@implementation UploadFoodImageViewController
@synthesize PlceHolder_label,TextView;

  - (void)viewDidLoad
    {
       [super viewDidLoad];
    }


 - (BOOL)textViewShouldBeginEditing:(UITextView *)textView{

       if([textView isEqual:TextView]){
            [PlceHolder_label setHidden:YES];
            [self.tabScrlVw setContentOffset:CGPointMake(0,150) animated:YES];
          }
      return YES;
    }

@end

别忘了连接textView和UILabel文件所有者从xib

我是这样做的:

UITextView2.h

#import <UIKit/UIKit.h>

@interface UITextView2 : UITextView <UITextViewDelegate> {
 NSString *placeholder;
 UIColor *placeholderColor;
}

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

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

@end

UITextView2.m

@implementation UITextView2

@synthesize placeholder, placeholderColor;

- (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*)notif {
    if ([[self placeholder] length]==0)
        return;
    if ([[self text] length]==0) {
        [[self viewWithTag:999] setAlpha:1];
    } else {
        [[self viewWithTag:999] setAlpha:0];
    }

}

- (void)drawRect:(CGRect)rect {
    if ([[self placeholder] length]>0) {
        UILabel *l = [[UILabel alloc] initWithFrame:CGRectMake(8, 8, 0, 0)];
        [l setFont:self.font];
        [l setTextColor:self.placeholderColor];
        [l setText:self.placeholder];
        [l setAlpha:0];
        [l setTag:999];
        [self addSubview:l];
        [l sizeToFit];
        [self sendSubviewToBack:l];
        [l release];
    }
    if ([[self text] length]==0 && [[self placeholder] length]>0) {
        [[self viewWithTag:999] setAlpha:1];
    }
    [super drawRect:rect];
}

- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
    [super dealloc];
}


@end