在 OS X 上使用 CGPDFContext 将文本添加到 PDF 页面

Question

我尝试通过 CGPDF 和 CGPDFContext 将文本添加到现有的 PDF 文件中，该文件有 5 页，但失败了。我已经设置了字体、DrawingMode、FillColor...我在代码中遗漏了什么吗？

    CGContextRef writeContext = NULL;
    CGRect mediaBox;
    CGPDFPageRef page;
    size_t i;

        page = CGPDFDocumentGetPage(inputDoc, 1);
        mediaBox = CGPDFPageGetBoxRect(page, kCGPDFMediaBox);

        if (! writeContext)
            writeContext = CGPDFContextCreateWithURL(url, &mediaBox, NULL);





        CGPDFContextBeginPage(writeContext, NULL);
        CGContextDrawPDFPage(writeContext, page);

        //Add text

        CGContextSelectFont(writeContext, "Helvetic", 26, kCGEncodingMacRoman);
        CGContextSetTextDrawingMode(writeContext, kCGTextFill);
        CGContextSetRGBFillColor(writeContext, 0, 0, 0, 1);
        const char *text="Hello Text Test";
        CGContextShowTextAtPoint(writeContext, 100, 100, text, strlen(text));


        //=========

        CGPDFContextEndPage(writeContext);
    }

    if (writeContext)
    {
        CGPDFContextClose(writeContext);
        CGContextRelease(writeContext);
    }

Answer 1

我发现您的字体名称 Helvetic 有错别字a

CGContextSelectFont(writeContext, "Helvetica", 26, kCGEncodingMacRoman);