如何在UITextView中插入占位符？

Question

有没有办法在UITextView类似的地方插入一个占位符UITextField？如果是,那么请发送任何链接或任何想法来实现此功能.

Answer 1

在UITextView中无法创建占位符,但您可以通过此方式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];
    }
}

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

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

或者您可以在textview中添加标签

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];

并设定

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

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

Answer 2

另一个简单的解决方法就是添加UILabel到您的UITextView子视图.

- (void)viewDidLoad
{
  [super viewDidLoad];

  // you might have to play around a little with numbers in CGRectMake method
  // they work fine with my settings
  placeholderLabel = [[UILabel alloc] initWithFrame:CGRectMake(10.0, 0.0, textView.frame.size.width - 20.0, 34.0)];
  [placeholderLabel setText:kDescriptionPlaceholder];
  // placeholderLabel is instance variable retained by view controller
  [placeholderLabel setBackgroundColor:[UIColor clearColor]];
  [placeholderLabel setFont:[challengeDescription font]];
  [placeholderLabel setTextColor:[UIColor lightGrayColor]];

  // textView is UITextView object you want add placeholder text to
  [textView addSubview:placeholderLabel];
}

- (void) textViewDidChange:(UITextView *)theTextView
{
  if(![textView hasText]) {
    [textView addSubview:placeholderLabel];
  } else if ([[textView subviews] containsObject:placeholderLabel]) {
    [placeholderLabel removeFromSuperview];
  }
}

- (void)textViewDidEndEditing:(UITextView *)theTextView
{
  if (![textView hasText]) {
    [textView addSubview:placeholderLabel];
  }
}

你甚至可以添加一些小动画来淡入/淡出UILabel你的东西.

- (void) textViewDidChange:(UITextView *)theTextView
{
  if(![textView hasText]) {
    [textView addSubview:placeholderLabel];
    [UIView animateWithDuration:0.15 animations:^{
      placeholderLabel.alpha = 1.0;
    }];
  } else if ([[textView subviews] containsObject:placeholderLabel]) {

    [UIView animateWithDuration:0.15 animations:^{
      placeholderLabel.alpha = 0.0;
    } completion:^(BOOL finished) {
      [placeholderLabel removeFromSuperview];
    }];
  }
}


- (void)textViewDidEndEditing:(UITextView *)theTextView
{
  if (![textView hasText]) {
    [textView addSubview:placeholderLabel];
    [UIView animateWithDuration:0.15 animations:^{
      placeholderLabel.alpha = 1.0;
    }];
}

Answer 3

另一个简单的解决方案是为placeholderLabel的隐藏属性设置YES/NO

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

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

Answer 4

-(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
  // NSLog(@"REPlace %@ %d",text,range.location);
  if(range.location==0 && ![text isEqualToString:@""])
  {
    placeholderlbl.hidden = YES;
  }
  else if(range.location==0)
  {
    placeholderlbl.hidden = NO;
  }

  return YES;
}