Audiobooks are fun to listen to during a commute, or anytime your eyes and hands are busy, but they come at a premium price with limited selection. Not to worry: in three simple steps, you can have your iPhone or iPad read any ebook to you without the need for additional apps.
Step 1: Adjust Accessibility settings
Go to Settings > General > Accessibility > Speech. Here, toggle on Speak Screen. Now, by simply swiping down with two fingers from the top of the screen, you can have Siri read any text that's currently displayed, no matter what app you're in.
Step 2: Temporarily turn off Auto-Lock
Go to Settings > General > Auto-Lock, and make sure Auto-Lock is set to Never. (For security purposes, be sure to turn Auto-Lock back on when you take a break from your book.) Making this change will keep your screen from shutting off, so your story won't be interrupted. (Pro tip: If you're driving, plug in a car charger to counter the extra drain on your battery.)
Step 3: Pick a book!
All that's left is to open a book in Kindle, iBooks, or wherever, and swipe two fingers down from the top of the screen to start Siri reading. Siri will read literally any visible text, so be sure to tap the screen once to remove any extraneous elements (such as the book's title, number of pages left, etc.). Siri even flips the pages as it reads along.
Once Siri starts reading, a small semi-transparent arrow appears on the side of the screen. Tap it to bring up several options, including the ability to pause/play speech, or to slow it down/speed it up. (The speaking rate can also be adjusted via a slider on the Speech menu in Settings.)
Siri doesn't read as well as a human being, of course, but once you get used to its monotone delivery and the occasional mispronounced word, it does a surprisingly good job. Go on and give it a try!