Iphone 向NSString添加省略号

我有下面的代码，我正在尝试使用核心文本绘制，这就是为什么我不能像UILabel那样剪裁文本。换句话说，我必须自己找出省略号（“…”）

我很难根据CGSize找到“…”的范围。解决这个问题的最好办法是什么

我是这样画的：

CFStringRef string = CFBridgingRetain(actualComment);
        CFMutableAttributedStringRef comment = CFAttributedStringCreateMutable(kCFAllocatorDefault, 0);
        CFAttributedStringReplaceString (comment ,CFRangeMake(0, 0), string);

        CGColorRef blue = CGColorRetain([UIColor colorWithRed:131/255.f green:204/255.f blue:253/255.f alpha:1.0].CGColor);
        CGColorRef gray = CGColorRetain([UIColor colorWithWhite:165/255.f alpha:1.0].CGColor);

        CFAttributedStringSetAttribute(comment, CFRangeMake(0, [name length]),kCTForegroundColorAttributeName, blue);
        CFAttributedStringSetAttribute(comment, CFRangeMake([name length],  [self.highlightItem_.comment length] - [name length]),kCTForegroundColorAttributeName, gray);

        CGColorRelease (blue);
        CGColorRelease (gray);

        CTFontRef nameFont = CTFontCreateWithName(CFBridgingRetain(kProximaNovaBold), 13.0f, nil);
        CFAttributedStringSetAttribute(comment,CFRangeMake(0, [name length]),kCTFontAttributeName,nameFont);

        CTFontRef commentFont = CTFontCreateWithName(CFBridgingRetain(kProximaNovaRegular), 13.0f, nil);
        CFAttributedStringSetAttribute(comment, CFRangeMake([name length],  [self.highlightItem_.comment length] - [name length]),kCTFontAttributeName,commentFont);

        CGFloat commentYOffset = floorf((self.commentHeight_ - commentSize.height)/2);

        CGContextSaveGState(context);
        CGRect captionFrame = CGRectMake(0, 0, rect.size.width - 80, commentSize.height);
        CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(comment);
        CGMutablePathRef captionFramePath = CGPathCreateMutable();
        CGPathAddRect(captionFramePath, NULL, captionFrame);

        CTFrameRef mainCaptionFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), captionFramePath, NULL);

        CGContextRef context = UIGraphicsGetCurrentContext();
        CGContextSetTextMatrix(context, CGAffineTransformIdentity);
        CGContextTranslateCTM(context, self.buttonSize_ + 25, self.imageHeight_ + self.commentHeight_ + 6 - commentYOffset);
        CGContextScaleCTM(context, 1.0, -1.0);

        CTFrameDraw(mainCaptionFrame, context);
        CGContextRestoreGState(context);

编辑

（我在这里的原始答案没有用；它不能处理多行。如果有人想查看历史记录，请查看编辑历史记录。我删除了它，因为它造成的混乱比它解决的要多。当前答案是正确的代码。）

您需要做的是让

CTFramesetter

计算出除最后一行之外的所有行。然后，如果需要，可以手动截断最后一个

- (void)drawRect:(CGRect)rect
{
  CGContextRef context = UIGraphicsGetCurrentContext();
  CGContextSetTextMatrix(context, CGAffineTransformIdentity);

  CGRect pathRect = CGRectMake(50, 200, 200, 40);
  CGPathRef path = CGPathCreateWithRect(pathRect, NULL);

  CFAttributedStringRef attrString = (__bridge CFTypeRef)[self attributedString];

  // Create the framesetter using the attributed string
  CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(attrString);

  // Create a single frame using the entire string (CFRange(0,0))
  // that fits inside of path.
  CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), path, NULL);

  // Draw the lines except the last one
  CFArrayRef lines = CTFrameGetLines(frame);
  CFIndex lineCount = CFArrayGetCount(lines);
  CGPoint origins[lineCount]; // I'm assuming that a stack variable is safe here.
                              // This would be bad if there were thousdands of lines, but that's unlikely.
  CTFrameGetLineOrigins(frame, CFRangeMake(0, 0), origins);
  for (CFIndex i = 0; i < lineCount - 1; ++i) {
    CGContextSetTextPosition(context, pathRect.origin.x + origins[i].x, pathRect.origin.y + origins[i].y);
    CTLineDraw(CFArrayGetValueAtIndex(lines, i), context);
  }

  ///
  /// HERE'S THE INTERESTING PART
  ///
  // Make a new last line that includes the rest of the string.
  // The last line is already truncated (just with no truncation mark), so we can't truncate it again
  CTLineRef lastLine = CFArrayGetValueAtIndex(lines, lineCount - 1);
  CFIndex lastLocation = CTLineGetStringRange(lastLine).location;
  CFRange restRange = CFRangeMake(lastLocation, CFAttributedStringGetLength(attrString) - lastLocation);
  CFAttributedStringRef restOfString = CFAttributedStringCreateWithSubstring(NULL, attrString, restRange);
  CTLineRef restLine = CTLineCreateWithAttributedString(restOfString);


  // We need to provide the truncation mark. This is an ellipsis (Cmd-semicolon).
  // You could also use "\u2026". Don't use dot-dot-dot. It'll work, it's just not correct.
  // Obviously you could cache this…
  CTLineRef ellipsis = CTLineCreateWithAttributedString((__bridge CFTypeRef)
                                                        [[NSAttributedString alloc] initWithString:@"…"]);

  // OK, now let's truncate it and draw it. I'm being a little sloppy here. If ellipsis could possibly
  // be wider than the path width, then this will fail and truncateLine will be NULL and we'll crash.
  // Don't do that.
  CTLineRef truncatedLine = CTLineCreateTruncatedLine(restLine,
                                                      CGRectGetWidth(pathRect),
                                                      kCTLineTruncationEnd,
                                                      ellipsis);
  CGContextSetTextPosition(context, pathRect.origin.x + origins[lineCount - 1].x, pathRect.origin.y + origins[lineCount - 1].y);
  CTLineDraw(truncatedLine, context);

  CFRelease(truncatedLine);
  CFRelease(ellipsis);
  CFRelease(restLine);
  CFRelease(restOfString);
  CFRelease(frame);
  CFRelease(framesetter);
  CGPathRelease(path);
}

-（void）drawRect:（CGRect）rect
{
CGContextRef context=UIGraphicsGetCurrentContext（）；
CGContextSetTextMatrix（上下文，CGAffineTransformity）；
CGRect pathRect=CGRectMake（5020020040）；
CGPathRef path=CGPathCreateWithRect（pathRect，NULL）；
CFAttributedStringRef属性字符串=（uu桥CFTypeRef）[自属性字符串]；
//使用属性化字符串创建框架设置器
CTFramesetterRef framesetter=CTFramesetterCreateWithAttributedString（attrString）；
//使用整个字符串创建单个帧（CFRange（0,0））
//这符合路径的内部。
CTFrameRef frame=CTFramesetterCreateFrame（framesetter，CFRangeMake（0，0），path，NULL）；
//画除最后一条线以外的线
CFArrayRef lines=CTFrameGetLines（帧）；
CFIndex lineCount=CFArrayGetCount（行）；
CGPoint origins[lineCount]；//我假设堆栈变量在这里是安全的。
//如果有上千行的话，这会很糟糕，但这不太可能。
CTFrameGetLineOriginates（框架，CFRangeMake（0,0），原点）；
对于（CFIndex i=0；i

像这样的东西怎么样

- (NSString *)truncate:(NSString *)string toWidth:(CGFloat)width withFont:(UIFont *)font {

    CGSize size = [string sizeWithFont:font];
    if (size.width <= width) return string;

    NSString *truncatedString = [string copy];
    NSString *ellipticalString = [truncatedString stringByAppendingString:@"..."];
    size = [ellipticalString sizeWithFont:font];

    while (size.width > width && truncatedString.length) {
        truncatedString = [truncatedString substringToIndex:(truncatedString.length-1)];
        ellipticalString = [truncatedString stringByAppendingString:@"..."];
        size = [ellipticalString sizeWithFont:font];
    }
    return ellipticalString;
}

-（NSString*）截断：（NSString*）字符串到宽度：（CGFloat）宽度，使用font:（UIFont*）字体{
CGSize size=[字符串大小WithFont:font]；
if（size.width&&truncatedString.length）{
truncatedString=[truncatedString子字符串到索引：（truncatedString.length-1）]；
ellipticalString=[truncatedString stringByAppendingString:@“…”；
大小=[ellipticalString sizeWithFont:font]；
}
返回椭圆字符串；
}

最简单的方法

NSString *theText = @"bla blah bla bhla bla bla";
NSMutableParagraphStyle *style = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
[style setLineBreakMode:NSLineBreakByTruncatingTail];
[theText drawInRect:dirtyRect withAttributes:[NSDictionary dictionaryWithObjectsAndKeys:style, NSParagraphStyleAttributeName,nil]];

---

对于

，您可以使用

NSString drawAtPoint:forWidth:withFont:lineBreakMode:

（或类似）方法将

nslinebreakbytruncingtail

传递为换行模式吗？@rmaddy我编辑了上面的帖子，以显示我是如何绘制文本的。实际上我没有使用DrawatPoint，我很确定有一个自动生成椭圆的工具，尽管我现在找不到。（我想可能是NSFont，但我在那里没有看到。）是的..几天来我一直在试图弄清楚这一点，但找不到它将字符串勾入标签（不需要在任何地方显示）。使用sizeThatFits：确定字符串是否适合标签。在该示例中，我没有看到任何NSLineBreakMode。我实际上在最后调用了CFRelease，我现在在此处显示它是的，但是示例中有

kCTParagraphStyleSpecifierAlignment

，换行符基本上是一样的。虽然我非常喜欢这个解决方案，而且它是最接近的解决方案，但问题是KCTLineBreakByTruncingTail只显示第一行。我尝试添加一些属性来更改属性字符串的颜色，但被截断的椭圆不再起作用。。当我不在中添加颜色属性时。。它起作用了。。有什么想法吗

NSString *theText = @"bla blah bla bhla bla bla";
NSMutableParagraphStyle *style = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
[style setLineBreakMode:NSLineBreakByTruncatingTail];
[theText drawInRect:dirtyRect withAttributes:[NSDictionary dictionaryWithObjectsAndKeys:style, NSParagraphStyleAttributeName,nil]];