iOS：CGPDFContextAddDocumentMetadata 的示例代码或示例

Question

我需要使用 Apple 的 Objective C SDK 将一些自定义元数据嵌入到 PDF 文件中。是否有任何可用的示例代码可以做到这一点？

我需要的是非常基本的。打开现有的 pdf 并添加一些元数据，然后保存。

存储的信息示例如下：客户姓名、联系电话、订购的商品。

我看到这个“CGPDFContextAddDocumentMetadata”支持元数据，但我不知道元数据是什么样的，以及它是如何传递给这个函数的。

任何帮助将不胜感激...:)

Answer 1

元数据是元数据（当然，Adobe 建议您使用 XMP XML）。只要您创建一个有效的 CFDataRef 并将其传递给 arg 2，您就可以很好地处理任何事情。例如，以下是如何将字符串“Hello World”传递到 PDF 的元数据中：

void MakeAPDF()
{

    CGRect mediaRect = CGRectMake(0, 0, 400, 600);
    // use your own rect instead

    CFMutableDataRef result = CFDataCreateMutable(kCFAllocatorDefault, 0);
    CGDataConsumerRef PDFDataConsumer = CGDataConsumerCreateWithCFData(result);

    // mark the PDF as coming from your program
    CFMutableDictionaryRef auxInfo = CFDictionaryCreateMutable(kCFAllocatorDefault, 1, NULL, NULL);
    CFDictionaryAddValue(auxInfo, kCGPDFContextCreator, CFSTR("Your Programs Name"));
    CFDictionaryRef auxillaryInformation = CFDictionaryCreateCopy(kCFAllocatorDefault, auxInfo);
    CFRelease(auxInfo);

    // create a context to draw into
    CGContextRef graphicContext = CGPDFContextCreate(PDFDataConsumer, &mediaRect, auxillaryInformation);
    CFRelease(auxillaryInformation);
    CGDataConsumerRelease(PDFDataConsumer);

    // actually make the call to embed your String
    NSString* str= @"Hello World";
    NSData* data=[str dataUsingEncoding:NSUTF8StringEncoding];
    CFDataRef cfdata = CFDataCreate(NULL, [data bytes], [data length]);

    CGPDFContextAddDocumentMetadata(graphicContext, cfdata);

    CGContextBeginPage(graphicContext, &mediaRect);
    // do your drawing, like this grey rectangle
    CGContextSetGrayFillColor(graphicContext, 0.5, 0.5);
    CGContextAddRect(graphicContext, mediaRect);
    CGContextFillPath(graphicContext);
    // end your drawing

    CGContextEndPage(graphicContext);
    CGContextFlush(graphicContext);
    CGPDFContextClose(graphicContext);    
}

XMP 文件可能如下所示：

<?xpacket begin="" id="W5M0MpCehiHzreSzNTczkc9d"?>
<x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="Adobe XMP Core 4.2.1-c041">
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" >
<rdf:Description rdf:about="" xmlns:dc="http://purl.org/dc/elements/1.1/">
  <dc:format>application/pdf</dc:format>
  <dc:title>
    <rdf:Alt>
      <rdf:li />
    </rdf:Alt>
  </dc:title>
  <dc:description>
    <rdf:Alt>
      <rdf:li />
    </rdf:Alt>
  </dc:description>
  <dc:creator>
    <rdf:Seq>
      <rdf:li />
    </rdf:Seq>
  </dc:creator>
</rdf:Description>
<rdf:Description rdf:about="" xmlns:pdf="http://ns.adobe.com/pdf/1.3/">
  <pdf:Keywords />
  <pdf:Producer />
</rdf:Description>
<rdf:Description rdf:about="" xmlns:xmp="http://ns.adobe.com/xap/1.0/">
  <xmp:CreatorTool />
  <xmp:CreateDate>2011-02-10T11:41:05+02:00</xmp:CreateDate>
  <xmp:ModifyDate>2011-02-10T11:41:06+02:00</xmp:ModifyDate>
</rdf:Description></rdf:RDF>
</x:xmpmeta>
<?xpacket end="w"?>

Answer 2

UIKit 有一些方法可以让这更简单：

// use your own rect instead
CGRect pageRect = CGRectMake(0, 0, 400, 600);

// mark the PDF as coming from your program
NSDictionary *auxillaryInformation = @{(NSString *)kCGPDFContextCreator: @"Koedal, Inc."};
UIGraphicsBeginPDFContextToFile([[self URLOfPDF] path], pageRect, auxillaryInformation);


// Embed metadata into PDF, I'm pulling it from a textView
NSString *PDFMetadata = self.metadataTextView.text;
NSData *data = [PDFMetadata  dataUsingEncoding:NSUTF8StringEncoding];

CGContextRef PDFContext = UIGraphicsGetCurrentContext();
CGPDFContextAddDocumentMetadata(PDFContext, (CFDataRef)data);

NSDictionary *textAttributes = @{ NSFontAttributeName : [UIFont boldSystemFontOfSize:20],
                                  NSForegroundColorAttributeName : [UIColor blackColor]
                                  };

// do your drawing, like drawing this string
UIGraphicsBeginPDFPage();
NSString *content = self.contentTextField.text;
[content drawAtPoint:CGPointMake(150, 280) withAttributes:textAttributes];

// end your drawing
UIGraphicsEndPDFContext();