PDFKit PDFAnnotationWidgetSubtypeSignature

Sorry if this is the wrong group, I couldn't a find a PDFKit specific group.

I have an app that downloads a PDF consent form that the user can ask a client to sign and have it sent back to a server.

I can download and display the PDF but I'm struggling with the signature bit. The code below will draw a box with a cross in it on the simulator but isn't allowing the mouse to draw a signature.

The documentation on this seems a bit light.

Has anybody got the signature to work?

My PDFView has some code:

 PDFView *view;

     ...

   view.autoScales = NO ;
   view.displayDirection = kPDFDisplayDirectionVertical;
   view.displayMode = kPDFDisplaySinglePageContinuous;
   view.displaysRTL = YES ;
   [view setDisplaysPageBreaks:YES];
   [view setDisplayBox:kPDFDisplayBoxTrimBox];

   view.document = _dataLink.pdf;

   // This locates the one occuarnce that I need to find.
   NSArray *searchResults = [view.document findString:@"Signauture:" withOptions:NSLiteralSearch];

   if (searchResults.count > 0)
     {
     // If multiple signature blocks found use the last one.
     PDFSelection *i = [searchResults objectAtIndex:searchResults.count - 1];

     PDFPage *page = [i.pages objectAtIndex:0];
     page.displaysAnnotations = YES;

     CGRect r = [i boundsForPage:page]; // CGRect of the search string.
     r.size.width = 360; // make it bigger so that the user has room to sign.
     r.size.height = 65;

     PDFAnnotation *ann = [[PDFAnnotation alloc] initWithBounds:r
                                                      forType:PDFAnnotationSubtypeWidget
                                               withProperties:nil];

     PDFBorder *border = [[PDFBorder alloc] init];
     border.lineWidth = 2.0;

     ann.border = border;
     ann.color = [UIColor blueColor];
     ann.backgroundColor = [UIColor darkGrayColor];
     ann.widgetFieldType = PDFAnnotationWidgetSubtypeSignature;
     ann.fieldName = @"Signature";
     ann.caption = @"Signature:";
     ann.shouldDisplay = YES;
     ann.shouldPrint = YES;

     [page addAnnotation:ann];

     // Just in case any of these make a differemce - no they don't
     [view setNeedsDisplay];
     [view annotationsChangedOnPage:page];
     }