Question

如何在目标c iphone中加下划线？是否有任何UILabel下划线文本的方法？

Answer 1

子类UILabel并覆盖drawRect方法，如下所示。下划线将same text color和text alignment作为标签：

- (void)drawRect:(CGRect)rect
{
    if([[self.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] length])
    {
        CGContextRef ctx = UIGraphicsGetCurrentContext();
        const CGFloat* colors = CGColorGetComponents(self.textColor.CGColor);
        CGContextSetRGBStrokeColor(ctx, colors[0], colors[1], colors[2], 1.0); // RGBA
        CGContextSetLineWidth(ctx, 1.0f);
        CGSize tmpSize = [self.text sizeWithFont:self.font constrainedToSize:CGSizeMake(200, 9999)];

        // check text alignment
        if(self.textAlignment == UITextAlignmentLeft) {
            CGContextMoveToPoint(ctx, 0, self.bounds.size.height - 1);
            CGContextAddLineToPoint(ctx, tmpSize.width, self.bounds.size.height - 1);
        }else if(self.textAlignment == UITextAlignmentCenter) {
            CGFloat startPoint = (self.frame.size.width - tmpSize.width) / 2;
            CGContextMoveToPoint(ctx, startPoint, self.bounds.size.height - 1);
            CGContextAddLineToPoint(ctx, tmpSize.width + startPoint, self.bounds.size.height - 1);
        }else if (self.textAlignment == UITextAlignmentRight) {
            CGFloat startPoint = (self.frame.size.width - tmpSize.width);
            CGContextMoveToPoint(ctx, startPoint, self.bounds.size.height - 1);
            CGContextAddLineToPoint(ctx, self.frame.size.width, self.bounds.size.height - 1);
        }

        CGContextStrokePath(ctx);
    }
    [super drawRect:rect];
}

Answer 2

您可以从UILabel继承并覆盖drawRect方法：

- (void)drawRect:(CGRect)rect {
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextSetRGBStrokeColor(ctx, 207.0f/255.0f, 91.0f/255.0f, 44.0f/255.0f, 1.0f); // RGBA
    CGContextSetLineWidth(ctx, 1.0f);

    CGContextMoveToPoint(ctx, 0, self.bounds.size.height - 1);
    CGContextAddLineToPoint(ctx, self.bounds.size.width, self.bounds.size.height - 1);

    CGContextStrokePath(ctx);

    [super drawRect:rect];  
}

Answer 3

简单地说，UILabel中没有可用的高级格式。

如果您正在寻找的是一个链接，那么您最好使用UIWebView，并为其提供一些“自制HTML”，如“我的链接”。然后，您可以在webview的委托中单击webview。

Answer 4

使用属性字符串：

NSAttributedString* attrString = [[NSAttributedString alloc] initWithString:@"Your String"]
[attrString addAttribute:(NSString*)kCTUnderlineStyleAttributeName 
                   value:[NSNumber numberWithInt:kCTUnderlineStyleSingle] 
                   range:(NSRange){0,[attrString length]}];

然后覆盖标签 - （void）drawTextInRect：（CGRect）aRect并以如下方式呈现文本：

CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSaveGState(ctx);
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attrString);
drawingRect = self.bounds;
CGMutablePathRef path = CGPathCreateMutable();
CGPathAddRect(path, NULL, drawingRect);
textFrame = CTFramesetterCreateFrame(framesetter,CFRangeMake(0,0), path, NULL);
CGPathRelease(path);
CFRelease(framesetter);
CTFrameDraw(textFrame, ctx);
CGContextRestoreGState(ctx);

或者更好的是，而不是覆盖只使用Olivier Halligon创建的OHAttributedLabel。他还支持自定义链接以及自定义颜色。

iphone中的文字下划线

4 个答案: