Contex Drawing + Pagination

I don't think you need the code which flips the PDF upside down. I've done this before (manual pagination, but without a scroll view) and never had to flip the context vertically. My main concern is that you are doing it on every iteration - if you have a valid reason for flipping it, you probably don't need it in the loop, but just once before the loop begins. Also the code CGContextTranslateCTM(pdfContext,0,-ty); might need to be replaced with CGContextTranslateCTM(pdfContext,0,heightOfPdf);

If that doesn't work, try UIGraphicsBeginPDFPage(); instead of CGContextBeginPage(), that's the only major difference between your code and mine.

This github project can definitely help you.

- (void) renderPageAtIndex:(NSUInteger)index inContext:(CGContextRef)ctx {
CGPDFPageRef page = CGPDFDocumentGetPage(pdf, index + 1);
CGAffineTransform transform = aspectFit(CGPDFPageGetBoxRect(page, kCGPDFMediaBox),
                                        CGContextGetClipBoundingBox(ctx));
CGContextConcatCTM(ctx, transform);
CGContextDrawPDFPage(ctx, page);

}

Found this link to render a PDF, it says about multiple pages but haven't shown an implementation. It doesnt straight away answer to your question but it tells a simpler method to render a pdf with much less translation and transforms.

Render PDF

Generate Multipage PDF -anoop

You could consider using a UIScrollView to layout your separate PDF pages. The following method loads each PDF page in a view (PDFView) and adds it to the scroll view content in a centered fashion:

- (void) loadPDFAtPath:(NSString *)path
{
    NSURL *pdfUrl = [NSURL fileURLWithPath:path];
    CGPDFDocumentRef document = CGPDFDocumentCreateWithURL((__bridge CFURLRef)pdfUrl);

    float height = 0.0;

    for(int i = 0; i < CGPDFDocumentGetNumberOfPages(document); i++) {
        CGPDFPageRef page = CGPDFDocumentGetPage(document, i + 1);
        PDFView *pdfView = [[PDFView alloc] initPdfViewWithPageRef:page];

        CGRect pageSize = CGPDFPageGetBoxRect(page, kCGPDFCropBox);
        pv.frame = CGRectMake((self.frame.size.width / 2.0) - pageSize.size.width / 2.0, height, pageSize.size.width, pageSize.size.height);
        height += pageSize.size.height + SOME_SPACE_IN_BETWEEN_PAGES;

        // self is a subclass of UIScrollView
        [self addSubview:pdfView];
        [pdfView setNeedsDisplay];
    }

    CGPDFDocumentRelease(document);
    [self setContentSize:CGSizeMake(self.frame.size.width, height)];
}

In this case, PDFView is responsible for rendering a single CGPDFPageRef in its drawRect or drawLayer implementation.