It’s called UP: My name is Dug, and was released on the App Store this week. It’s not based on the film, though: it’s “a new lovely adventure with Dug and his friends” – an original story.
That said, the voice narration does include voices from the film. The story focuses on Dug introducing your child to his pack, while hunting for a colourful bird. Disney promises lots of tappable interactivity as your children read, or are read to.
UP: My name is Dug costs £2.49 on the App Store, and is iPad-only.