Create PDF Thumb

+(UIImage *)createPDFThumb:(NSString *)pdfURL thumbSize:(CGSize)thumbSize {
    NSURL *url = [NSURL URLWithString:pdfURL];
    CGPDFDocumentRef pdf = CGPDFDocumentCreateWithURL((CFURLRef) url);
    CGPDFPageRef page;

    CGRect aRect = CGRectMake(0, 0, thumbSize.width, thumbSize.height);
    UIGraphicsBeginImageContext(aRect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    UIImage* thumbnailImage;

    NSUInteger totalNum = CGPDFDocumentGetNumberOfPages(pdf);

    for (int i = 0; i < totalNum; i++ ) {
        CGContextSaveGState(context);
        CGContextTranslateCTM(context, 0.0, aRect.size.height);
        CGContextScaleCTM(context, 1.0, -1.0);

        CGContextSetGrayFillColor(context, 1.0, 1.0);
        CGContextFillRect(context, aRect);

        // Grab the first PDF page
        page = CGPDFDocumentGetPage(pdf, i + 1);
        CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(page, kCGPDFMediaBox, aRect, 0, true);

        // And apply the transform.
        CGContextConcatCTM(context, pdfTransform);
        CGContextDrawPDFPage(context, page);

        // Create the new UIImage from the context
        thumbnailImage = UIGraphicsGetImageFromCurrentImageContext();

        CGContextRestoreGState(context);
    }

    UIGraphicsEndImageContext();
    CGPDFDocumentRelease(pdf);

    return thumbnailImage;
}