Objective-C
Extract Metadata XML from PDF

Demonstrates how to extract the metadata XML from a PDF.
Chilkat Objective-C Downloads

Objective-C
#import <CkoPdf.h>
#import <CkoStringBuilder.h>
#import <CkoXml.h>
#import <NSString.h>

BOOL success = NO;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

CkoPdf *pdf = [[CkoPdf alloc] init];

success = [pdf LoadFile: @"qa_data/pdf/blank_with_metadata.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

CkoStringBuilder *sbXml = [[CkoStringBuilder alloc] init];
// Note: Not all PDF files have metadata.  Metadata is optional.
success = [pdf GetMetadata: sbXml];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

CkoXml *xml = [[CkoXml alloc] init];
[xml LoadSb: sbXml autoTrim: YES];

NSLog(@"%@",[xml GetXml]);

// Sample PDF metadata XML:
// (Code for parsing follows)

// Use this online tool to generate parsing code from sample XML: 
// Generate Parsing Code from XML

// <?xml version="1.0" encoding="utf-8"?>
// <x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="Adobe XMP Core 9.1-c001 79.675d0f7, 2023/06/11-19:21:16        ">
//     <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
//         <rdf:Description rdf:about="" xmlns:xmp="http://ns.adobe.com/xap/1.0/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xmpMM="http://ns.adobe.com/xap/1.0/mm/" xmlns:pdf="http://ns.adobe.com/pdf/1.3/" xmlns:xmpRights="http://ns.adobe.com/xap/1.0/rights/">
//             <xmp:ModifyDate>2024-11-27T11:33:12-06:00</xmp:ModifyDate>
//             <xmp:CreateDate>2024-11-27T11:28:23-06:00</xmp:CreateDate>
//             <xmp:MetadataDate>2024-11-27T11:33:12-06:00</xmp:MetadataDate>
//             <xmp:CreatorTool>Adobe Acrobat Pro (32-bit) 24.3.20112</xmp:CreatorTool>
//             <dc:format>application/pdf</dc:format>
//             <dc:title>
//                 <rdf:Alt>
//                     <rdf:li xml:lang="x-default">Blank</rdf:li>
//                 </rdf:Alt>
//             </dc:title>
//             <dc:creator>
//                 <rdf:Bag>
//                     <rdf:li>Chilkat Software</rdf:li>
//                 </rdf:Bag>
//             </dc:creator>
//             <dc:description>
//                 <rdf:Alt>
//                     <rdf:li xml:lang="x-default">Blank Document</rdf:li>
//                 </rdf:Alt>
//             </dc:description>
//             <dc:subject>
//                 <rdf:Bag>
//                     <rdf:li>blank</rdf:li>
//                     <rdf:li>metadata</rdf:li>
//                     <rdf:li>document</rdf:li>
//                 </rdf:Bag>
//             </dc:subject>
//             <xmpMM:DocumentID>uuid:34535ffa-b632-43f1-b1fd-80cea6fdc351</xmpMM:DocumentID>
//             <xmpMM:InstanceID>uuid:69ace620-4c54-407f-8d45-6eebc90f34c2</xmpMM:InstanceID>
//             <pdf:Producer>Adobe Acrobat Pro (32-bit) 24.3.20112</pdf:Producer>
//             <pdf:Keywords>blank; metadata; document</pdf:Keywords>
//             <xmpRights:WebStatement>https://www.chilkatsoft.com/</xmpRights:WebStatement>
//         </rdf:Description>
//     </rdf:RDF>
// </x:xmpmeta>

NSString *x_xmpmeta_xmlns_x = [xml GetAttrValue: @"xmlns:x"];
NSString *x_xmpmeta_x_xmptk = [xml GetAttrValue: @"x:xmptk"];
NSString *rdf_RDF_xmlns_rdf = [xml ChilkatPath: @"rdf:RDF|(xmlns:rdf)"];
NSString *rdf_Description_rdf_about = [xml ChilkatPath: @"rdf:RDF|rdf:Description|(rdf:about)"];
NSString *rdf_Description_xmlns_xmp = [xml ChilkatPath: @"rdf:RDF|rdf:Description|(xmlns:xmp)"];
NSString *rdf_Description_xmlns_dc = [xml ChilkatPath: @"rdf:RDF|rdf:Description|(xmlns:dc)"];
NSString *rdf_Description_xmlns_xmpMM = [xml ChilkatPath: @"rdf:RDF|rdf:Description|(xmlns:xmpMM)"];
NSString *rdf_Description_xmlns_pdf = [xml ChilkatPath: @"rdf:RDF|rdf:Description|(xmlns:pdf)"];
NSString *rdf_Description_xmlns_xmpRights = [xml ChilkatPath: @"rdf:RDF|rdf:Description|(xmlns:xmpRights)"];
NSString *xmp_ModifyDate = [xml GetChildContent: @"rdf:RDF|rdf:Description|xmp:ModifyDate"];
NSString *xmp_CreateDate = [xml GetChildContent: @"rdf:RDF|rdf:Description|xmp:CreateDate"];
NSString *xmp_MetadataDate = [xml GetChildContent: @"rdf:RDF|rdf:Description|xmp:MetadataDate"];
NSString *xmp_CreatorTool = [xml GetChildContent: @"rdf:RDF|rdf:Description|xmp:CreatorTool"];
NSString *dc_format = [xml GetChildContent: @"rdf:RDF|rdf:Description|dc:format"];
NSString *rdf_li_xml_lang = [xml ChilkatPath: @"rdf:RDF|rdf:Description|dc:title|rdf:Alt|rdf:li|(xml:lang)"];
NSString *rdf_li = [xml GetChildContent: @"rdf:RDF|rdf:Description|dc:title|rdf:Alt|rdf:li"];
rdf_li = [xml GetChildContent: @"rdf:RDF|rdf:Description|dc:creator|rdf:Bag|rdf:li"];
rdf_li_xml_lang = [xml ChilkatPath: @"rdf:RDF|rdf:Description|dc:description|rdf:Alt|rdf:li|(xml:lang)"];
rdf_li = [xml GetChildContent: @"rdf:RDF|rdf:Description|dc:description|rdf:Alt|rdf:li"];
int i = 0;
int count_i = [[xml NumChildrenHavingTag: @"rdf:RDF|rdf:Description|dc:subject|rdf:Bag|rdf:li"] intValue];
while (i < count_i) {
    xml.I = [NSNumber numberWithInt: i];
    rdf_li = [xml GetChildContent: @"rdf:RDF|rdf:Description|dc:subject|rdf:Bag|rdf:li[i]"];
    i = i + 1;
}

NSString *xmpMM_DocumentID = [xml GetChildContent: @"rdf:RDF|rdf:Description|xmpMM:DocumentID"];
NSString *xmpMM_InstanceID = [xml GetChildContent: @"rdf:RDF|rdf:Description|xmpMM:InstanceID"];
NSString *pdf_Producer = [xml GetChildContent: @"rdf:RDF|rdf:Description|pdf:Producer"];
NSString *pdf_Keywords = [xml GetChildContent: @"rdf:RDF|rdf:Description|pdf:Keywords"];
NSString *xmpRights_WebStatement = [xml GetChildContent: @"rdf:RDF|rdf:Description|xmpRights:WebStatement"];