如何在UITextView中插入占位符？

Question

有没有办法在 UITextView 中插入类似于 UITextField 的占位符？如果是，请向我发送任何链接或任何实现此功能的想法。

Answer 1

无法在 UITextView 中创建占位符，但您可以通过此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];
    }
}

或者您可以在文本视图中添加标签，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 *) 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案是只需将 UILabel 添加到您的 UITextView 子视图中。

- (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];
  }
}

如果您愿意的话，您甚至可以添加小动画来淡入/淡出 UILabel。

- (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;
}

Answer 5

您可以使用下面的函数来制作占位符，使用它您可以在其上设置占位符。

[self addTextViewPlaceholder:self.txtvComment withPlaceholder:@"COMMENT"];

-(void) addTextViewPlaceholder:(UITextView*) tView withPlaceholder:(NSString*) placeholder
{
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(9,8,tView.bounds.size.width - 16,0)];
    label.lineBreakMode = UILineBreakModeWordWrap;
    label.numberOfLines = 0;
    label.font = [UIFont systemFontOfSize:13.0];
    label.backgroundColor = [UIColor clearColor];
    label.textColor = [UIColor colorWithRed:0.7 green:0.7 blue:0.7 alpha:1.0];

    label.text = placeholder;
    label.alpha = 1;
    label.tag = 999;
    [tView addSubview:label];
    [label sizeToFit];
    if(![tView.text isEqualToString:@""])
        [label setAlpha:0];
    [label release];
}

您可以使用它来管理占位符文本。

- (void)textViewDidChange:(UITextView *)textView
{
    [self textChange:textView];
}

- (void)textChange:(UITextView *)textView
{
    if([textView.text length]>0)
        [[textView viewWithTag:999] setAlpha:0];
    else
        [[textView viewWithTag:999] setAlpha:1];
}

Answer 6

另一个解决方案是将占位符 UITextView 放在实际 UITextView 的顶部。给它相同的框架。为占位符 TextView 设置 placeholderTextView.enabled = NO。

然后，仅为普通 textView 设置委托并定义此 UITextViewDelegate 方法：

- (void)textViewDidChange:(UITextView *)textView
{
    NSLog(@"textViewDidChange");

    if(self.textView.text.length == 0)
    {
        self.placeholderTextView.hidden = NO;
    }
    else
    {
        self.placeholderTextView.hidden = YES;
    }
}