带有“-”字符的字符串在 iOS 的 drawrect 方法中未正确绘制

Question

我正在 iOS 中处理 coretext。

我通过将-drawRect 方法替换为以下代码，实现了自定义UIView：

- (void)drawRect:(CGRect)rect
{
    [super drawRect:rect];

    CGRect frameRect=CGRectMake(50, 200, 80, 15);
//    NSString *textToDraw=@"A-BCDEFGHIJKLM";
//    NSString *textToDraw=@"abc";

//    NSString *textToDraw=@"ABCDEFGHIJKLMNOPQRST";
    NSString *textToDraw=@"A-BCDEFGHIJ";
 //   NSString *textToDraw=@"A-BCDEFGHI";


    CFStringRef stringRef = (__bridge CFStringRef)textToDraw;
    NSMutableAttributedString* attString = [[NSMutableAttributedString alloc]initWithString:textToDraw];
    NSInteger _stringLength=[textToDraw length];

    CTTextAlignment theAlignment = kCTLeftTextAlignment; // kCTRightTextAlignment; //kCTCenterTextAlignment;
    CTParagraphStyleSetting theSettings[1] =
    {
        { kCTParagraphStyleSpecifierAlignment, sizeof(CTTextAlignment),&theAlignment
        }
    };

    CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(theSettings, 1);

    [attString addAttribute:(id)kCTParagraphStyleAttributeName value:(__bridge id)paragraphStyle range:NSMakeRange(0, _stringLength)];
    CFAttributedStringRef attrString =(__bridge CFAttributedStringRef) attString;
    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(attrString);
    CGMutablePathRef framePath = CGPathCreateMutable();
    CGPathAddRect(framePath, NULL, frameRect);
    // Get the frame that will do the rendering.
    CFRange currentRange = CFRangeMake(0, 0);
    CTFrameRef frameRef = CTFramesetterCreateFrame(framesetter, currentRange, framePath, NULL);
    CGPathRelease(framePath);
    // Get the graphics context.
    CGContextRef    currentContext = UIGraphicsGetCurrentContext();
    // Put the text matrix into a known state. This ensures
    // that no old scaling factors are left in place.
    CGContextSetTextMatrix(currentContext, CGAffineTransformIdentity);
    // Core Text draws from the bottom-left corner up, so flip
    // the current transform prior to drawing.
    CGContextTranslateCTM(currentContext, 0, frameRect.origin.y*2);
    CGContextScaleCTM(currentContext, 1.0, -1.0);
    // Draw the frame.
    CTFrameDraw(frameRef, currentContext);
    CGContextScaleCTM(currentContext, 1.0, -1.0);
    CGContextTranslateCTM(currentContext, 0, (-1)*frameRect.origin.y*2);
    CFRelease(frameRef);
    CFRelease(stringRef);
    CFRelease(framesetter);
}

在这里，当我将输入字符串设置为“ABCDEFGHIJKLMNOPQRST”时，它会将我所需的输出作为“ABCDEFGHIJ”，根据宽度“80”截断'。

但问题是当我将输入字符串作为“A-BCDEFGHIJ” 传递时，它给我的输出是“A-”。

至少应按宽度打印“A-BCDEFGHI”。但它只打印“A-”。 它没有正确截断。

我的代码中是否缺少某些内容？

以下是截图：

字符串“ABCDEFGHIJKLMNOPQRST”的输出：

字符串“A-BCDEFGHIJ”的输出：

请帮帮我。

提前致谢。

Answer 1

-，或者“连字符”是一个换行符，它开始一个新行（类似于\n）。

考虑使用 Unicode NON-BREAKING HYPHEN (U+2011)

例如

NSString *textToDraw = @"A\u2011BCDEFGHIJ";

查看更多：Unicode Line Breaking Algorithm