Question

Anyone succesfull tried to read the Catalog dictionary of a PDF document, using iPhone APIs? I’m not getting anything that makes sense: Most dictionaries inside the Catalog are empty.

Answer 1

Try this:

CGPDFDictionaryRef catalog = CGPDFDocumentGetCatalog(myDocument);
CGPDFDictionaryApplyFunction(catalog, streamInfoFunction, catalog);

The Catalog is basically a dictionary and you have you use a applier function on it as shown.

void streamInfoFunction ( const char *key,CGPDFObjectRef object, void *info )
{
NSLog(@"---------------------------------------------------------------------------------------------");
NSLog(@"Processing Stream Info");

NSString *keyStr = [NSString stringWithCString:key encoding:NSUTF8StringEncoding];
CGPDFDictionaryRef contentDict = (CGPDFDictionaryRef)info;

CGPDFObjectType objectType = CGPDFObjectGetType(object);
if(objectType == kCGPDFObjectTypeDictionary)
{
    CGPDFDictionaryRef value  = NULL;
    CGPDFDictionaryGetDictionary(contentDict, key, &value);
    NSLog(@"Value for key %@ is %d",keyStr,CGPDFDictionaryGetCount(value));
        //S.SNSLog(@"%@",value);
}
else if(objectType == kCGPDFObjectTypeArray)
{
    CGPDFArrayRef value  = NULL;
    CGPDFDictionaryGetArray(contentDict, key, &value);
    NSLog(@"Value for key %@ is %d",keyStr,CGPDFArrayGetCount(value));
        //S.SNSLog(@"%@",value);
}
else if(objectType == kCGPDFObjectTypeStream)
{
    CGPDFStreamRef value  = NULL;
    CGPDFDictionaryGetStream(contentDict, key, &value);
    NSLog(@"Processing for key %@",keyStr);
    CGPDFDataFormat dataFormat;
    CFDataRef streamData = CGPDFStreamCopyData(value, &dataFormat);
    CFShow(streamData);
    NSString *contentString = [[NSString alloc]initWithBytes:[(NSData*)streamData bytes] length:[(NSData*)streamData length] encoding:NSUTF8StringEncoding];
    NSLog(@"%@",contentString);

}
else if(objectType == kCGPDFObjectTypeInteger)
{
    CGPDFInteger integerValue;
    CGPDFDictionaryGetInteger(contentDict, key, &integerValue);
    NSLog(@"Processing for Key %@ value %d",keyStr,integerValue);

}
else if(objectType == kCGPDFObjectTypeName)
{
    const char *name;
    CGPDFDictionaryGetName(contentDict, key, &name);
    NSLog(@"Processing for key %@ value %s",keyStr,[NSString stringWithCString:name encoding:NSUTF8StringEncoding]);
}

NSLog(@"---------------------------------------------------------------------------------------------");

}

For a general reference, see: Fast and Lean PDF Viewer for iPhone / iPad / iOs – tips and hints?