If you are using an Apple device you can open, save and view your PDF patterns in iBooks.
Once you have signed into your account you can find your patterns in 'Pattern Library'.
Click on the pattern you would like to download and it will open in a new tab. You will have a prompt to iBooks in the right hand corner, if it disappears just hover your finger over the corner and it will reappear. It will look like this:
Click the link and your pattern will open in your iBooks library.