iOS: Sample Code or Examples for CGPDFContextAddDocumentMetadata - ios

Question

I need to embed some custom meta data to a PDF file using the Apple's Objective C SDK. Is there any working sample code available that does that?
What I need is very basic. Open an existing pdf and add some meta data and then save it.
Example of information stored will be like.... a customer's name, contact number, items ordered.
I saw that this "CGPDFContextAddDocumentMetadata" supports metadata but I don't know how the meta data look like and how is it used passed to this function.
Any help will be greatly appreciated...:)

Answer 1

Metadata is metadata (of course, it is recommended by Adobe that you use XMP XML). So long as you create a valid CFDataRef and pass it into arg two, you're pretty much good to go with anything. For example, here's how to pass the string "Hello World" into a PDF's metadata:
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);
}
An XMP file might look like this:
<?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 has some methods that make this simpler:
// 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();