另一个答案是:

https://github.com/gcamp/GCPlaceholderTextView

改变类UITextView在IB到GCPlaceholderTextView 并设置占位符属性

- (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。

在看完所有答案后，我意识到我需要一些简单的，同时可重用的东西，这样我就可以在我的项目中为所有uitextview添加相同的功能。最后我得到了以下代码:

extension UITextView {

// MARK: TextView PlaceHolderLabel Setup

func createPlaceHolderLabel(with text: String) {
    let lbl = UILabel()
    self.addSubview(lbl)

// Add your constraints here

    lbl.text = text
    lbl.textColor = .lightGray
}

// My Textview contains only one UILabel, and for my use case the below code works, tweak it according to your use case

// Lastly two methods to toggle between show and hide the placeholder label

func hidePlaceHolderLabel() {
    guard let lbl = self.subviews.first(where: { $0 is UILabel }) else { return }
    lbl.isHidden = true
}

func showPlaceHolderLabel() {
    guard let lbl = self.subviews.first(where: { $0 is UILabel }) else { return }
    lbl.isHidden = false
}

}

当UILabel作为子视图添加到UITextView时，textView游标位置和UILabel位置将不匹配，因此在占位符文本之前留下一个空间

class ViewController: UIViewController, UITextViewDelegate {
    var textView: UITextView!

override func viewDidLoad() {
    super.viewDidLoad()
    view.addSubview(textView)
    // Also setup textView constraints as per your need
    // Add placeholder to your textView
    // Leave one space before placeholder string
    textView.createPlaceHolderLabel(with: " Address")
    textView.delegate = self
}

然后在textViewdidChange方法中添加以下代码

func textViewDidChange(_ textView: UITextView) {
    if textView.text.isEmpty {
        textView.showPlaceHolderLabel()
    } else {
        textView.hidePlaceHolderLabel()
    }
}

它可以在所有uitextview中重用。

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

在h课上

@interface RateCommentViewController : UIViewController<UITextViewDelegate>{IBoutlet UITextview *commentTxtView;}

在。m类

- (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];
    }
}

我遵循了这个链接的代码。只有7个简单的步骤。它添加了一个UILabel的textView和隐藏/显示标签时，文本输入或从textView通过textView的textViewDidChangeSelection(_ textView: UITextView)委托方法。我将步骤放在代码上方的注释中。

// 1. make sure to include the UITextViewDelegate
class YourClass: UITextViewDelegate {

    @IBOutlet weak var textView : UITextView!

    // 2. create placeholder textLabel
    let placeHolderTextLabel: UILabel = {
        let placeholderLabel = UILabel()
        placeholderLabel.text = "Placeholder text..."
        placeholderLabel.sizeToFit()
        placeholderLabel.textColor = UIColor.lightGray
        return placeholderLabel
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        // 3. set textView delegate
        textView.delegate = self

        configurePlaceholderTextLabel()
    }


    func configurePlaceholderTextLabel() {

        // 4. add placeholder label to textView, set it's frame and font
        textView.addSubview(placeHolderTextLabel)
        placeHolderTextLabel.frame.origin = CGPoint(x: 5, y: (textView.font?.pointSize)! / 2)
        placeHolderTextLabel.font = UIFont.systemFont(ofSize: (textView.font?.pointSize)!)

        // 5. decide wether the placeHolderTextLabel is hidden or not depending on if there is or isn't text inside the textView
        placeHolderTextLabel.isHidden = !textView.text.isEmpty

    }

    // 6. implement textView delegate method to update the placeHolderTextLabel when the text is changed
    func textViewDidChangeSelection(_ textView: UITextView) {

        // 7. decide wether the placeHolderTextLabel is hidden or not depending on if there is or isn't text inside the textView when text in textView is changed
        placeHolderTextLabel.isHidden = !textView.text.isEmpty
    }

}