在UITextView内画一条线-NSAttributedString [英] Draw a line inside a UITextView - NSAttributedString

问题描述

我希望在由某些文本组成的UITextView中绘制一条可自定义的线(使用NSAttributedString)

这就是我尝试过的

NSString *unicodeStr = [NSString stringWithFormat:@"%C%C%C", 0x00A0, 0x0009, 0x00A0]; //nbsp, tab, nbsp
NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:unicodeStr];
NSRange strRange = NSMakeRange(0, str.length);

NSMutableParagraphStyle *const tabStyle = [[NSMutableParagraphStyle alloc] init];
tabStyle.headIndent = 16; //padding on left and right edges
tabStyle.firstLineHeadIndent = 16;
tabStyle.tailIndent = -16;
NSTextTab *listTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentCenter location:40 options:@{}]; //this is how long I want the line to be
tabStyle.tabStops = @[listTab];
[str  addAttribute:NSParagraphStyleAttributeName value:tabStyle range:strRange];
[str addAttribute:NSStrikethroughStyleAttributeName value:[NSNumber numberWithInt:2] range:strRange];

但是无论我为制表符停止位置(在这种情况下为40)和tailIndent(此处为-16)提供什么值，该行仅尊重headIndent并跨越整个UITextView宽度(当然要减去headIndent). /p>

编辑-我非常确定问题是因为我没有使用正确的unicode字符(尽管它们似乎是合乎逻辑的选择).万一这给了我一个提示，如果我在第二个nbsp之后添加一个空格，即朝末尾添加一个空格，则制表符将限制为单个制表符长度

解决方案

这是您的预期结果吗?

您可以尝试以下方法吗?

NSTextTab *listTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentCenter location:self.textView.frame.size.width - tabStyle.firstLineHeadIndent + tabStyle.tailIndent options:@{}];

这是完整的代码:

- (void) viewDidAppear:(BOOL)animated {
  [super viewDidAppear:animated];
  NSString *unicodeStr = @"\n\u00a0\t\t\n";
  NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:unicodeStr];
  NSRange strRange = NSMakeRange(0, str.length);

  NSMutableParagraphStyle *const tabStyle = [[NSMutableParagraphStyle alloc] init];
  tabStyle.headIndent = 16; //padding on left and right edges
  tabStyle.firstLineHeadIndent = 16;
  tabStyle.tailIndent = -70;
  NSTextTab *listTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentCenter location:self.textView.frame.size.width - tabStyle.headIndent + tabStyle.tailIndent options:@{}]; //this is how long I want the line to be
  tabStyle.tabStops = @[listTab];
  [str  addAttribute:NSParagraphStyleAttributeName value:tabStyle range:strRange];
  [str addAttribute:NSStrikethroughStyleAttributeName value:[NSNumber numberWithInt:2] range:strRange];

  NSAttributedString *htmlStr = [[NSAttributedString alloc] initWithData:[@"<h1>Lorem ipsum dolor sit er elit lamet</h1>" dataUsingEncoding:NSUnicodeStringEncoding] options:@{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil];

  [str insertAttributedString:htmlStr atIndex:0];
  [str appendAttributedString:htmlStr];

  self.textView.attributedText = str;
}

I wish to draw a customizable line inside a UITextView consisting of some text (using NSAttributedString)

Here's what I tried

NSString *unicodeStr = [NSString stringWithFormat:@"%C%C%C", 0x00A0, 0x0009, 0x00A0]; //nbsp, tab, nbsp
NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:unicodeStr];
NSRange strRange = NSMakeRange(0, str.length);

NSMutableParagraphStyle *const tabStyle = [[NSMutableParagraphStyle alloc] init];
tabStyle.headIndent = 16; //padding on left and right edges
tabStyle.firstLineHeadIndent = 16;
tabStyle.tailIndent = -16;
NSTextTab *listTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentCenter location:40 options:@{}]; //this is how long I want the line to be
tabStyle.tabStops = @[listTab];
[str  addAttribute:NSParagraphStyleAttributeName value:tabStyle range:strRange];
[str addAttribute:NSStrikethroughStyleAttributeName value:[NSNumber numberWithInt:2] range:strRange];

But no matter what value I provide for the tab stop location (40 in this case) and tailIndent (-16 here), the line only respects the headIndent and spans the entire UITextView width (minus the headIndent of course).

EDIT - I am pretty sure the issue is because I am not using the correct unicode chars (although they seem to be the logical choice). In case this gives someone a hint, if I add a space after the 2nd nbsp i.e. towards the end, the tab is limited to a single tab length

解决方案

Is it your expected result?

Can you try this:

NSTextTab *listTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentCenter location:self.textView.frame.size.width - tabStyle.firstLineHeadIndent + tabStyle.tailIndent options:@{}];

And this is the full code:

- (void) viewDidAppear:(BOOL)animated {
  [super viewDidAppear:animated];
  NSString *unicodeStr = @"\n\u00a0\t\t\n";
  NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:unicodeStr];
  NSRange strRange = NSMakeRange(0, str.length);

  NSMutableParagraphStyle *const tabStyle = [[NSMutableParagraphStyle alloc] init];
  tabStyle.headIndent = 16; //padding on left and right edges
  tabStyle.firstLineHeadIndent = 16;
  tabStyle.tailIndent = -70;
  NSTextTab *listTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentCenter location:self.textView.frame.size.width - tabStyle.headIndent + tabStyle.tailIndent options:@{}]; //this is how long I want the line to be
  tabStyle.tabStops = @[listTab];
  [str  addAttribute:NSParagraphStyleAttributeName value:tabStyle range:strRange];
  [str addAttribute:NSStrikethroughStyleAttributeName value:[NSNumber numberWithInt:2] range:strRange];

  NSAttributedString *htmlStr = [[NSAttributedString alloc] initWithData:[@"<h1>Lorem ipsum dolor sit er elit lamet</h1>" dataUsingEncoding:NSUnicodeStringEncoding] options:@{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil];

  [str insertAttributedString:htmlStr atIndex:0];
  [str appendAttributedString:htmlStr];

  self.textView.attributedText = str;
}

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