I just did this. I created a folder in my email app for the email Towers send you after your purchase for quick access when I'm on park. I just open the email app, go in to the folder, open the email, touch 'view my tickets' and it takes you to the page pictured.
The page has all my tickets in collapsible list form as shown, just touch the arrow on the right and the ticket barcode comes up on the screen. No messing around with box offices or carrying around loads of bits of paper! All a physical ticket is is a paper copy of the exact same barcode from your phone screen.