iOS How to get PDF links from CGPDFDocument?

-(void)drawInContext:(CGContextRef)context
{
    // PDF page drawing expects a Lower-Left coordinate system, 
    // so we flip the coordinate system before we start drawing.
    CGContextTranslateCTM(context, 0.0, self.bounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);

    // Grab the first PDF page
    CGPDFPageRef page = CGPDFDocumentGetPage(pdf, pageNumber);
    // We're about to modify the context CTM to draw the PDF page
    //  where we want it, so save the graphics state 
    // in case we want to do more drawing
    CGContextSaveGState(context);
    // CGPDFPageGetDrawingTransform provides an easy way to get the
    // transform for a PDF page. It will scale down to fit, including any 
    // base rotations necessary to display the PDF page correctly. 
    CGAffineTransform pdfTransform = 
            CGPDFPageGetDrawingTransform(page, 
                    kCGPDFCropBox, self.bounds, 0, true);
    // And apply the transform.
    CGContextConcatCTM(context, pdfTransform);
    // Finally, we draw the page 
    // and restore the graphics state for further manipulations!
    CGContextDrawPDFPage(context, page);
    CGContextRestoreGState(context);
}