Swift - Convert Multi Page Pdf to Single Image

My project can be downloaded from the following GitHub repo: [login to view URL] The application currently has a locally stored PDF file that is multi page. It has a function, as copied from this blog post that will convert the PDF to an image: [login to view URL] I have a simple function set up so that when the "save PDF as photo" button is pressed from the main storyboard, it will prompt the user with the UIActivityViewController that will allow the user to save the photo to the gallery. This is great, but I need to it to save all the PDF pages into one large image. Would tyou be able to help me with this? (Under as micro project but can stretch the price)