Mercer Mayer has been writing Little Critter books since the grown-up children were sleeping in cribs. My kids loved the series and had me read it to them hundreds of times. Little Critter is a hedgehog-looking animal that very small children can easily relate to as he goes about his simple adventures. Each of the over 200 books featuring Little Critter tells a very simple story, providing positive reinforcement for very small kids who sometimes need to be told how competent and good they are, even if they sometimes get things wrong. All of the books are whimsically illustrated and quite funny in a gentle and childlike manner. These are very simple books without any hard words and are very appropriate for little ones starting at about one year old. Each of them sells for US$1.99, and they are universal apps that work well on all iOS devices -- of course, they look better on the larger screen of an iPad.
Oceanhouse Media has released four of the series so far, and I'm sure that, as time goes by, many more will show up. They all use the Oceanhouse engine that has become a standard in the industry. As in all the OM books, there are three options. AutoPlay is for the smallest of children. Each page is read as the built-in animation zooms now and then to highlight what's important on the page. The pages turn automatically as the sound effects play, and each word is highlighted as it's read. Read To Me provides a bit of autonomy; the young reader swipes the pages to turn them, and the text is read by a very young sounding voice. Touching the text block will cause it to be read again. Read It Myself deletes the narration until the text block is tapped in case the child has a problem with a word or two. In all three options, touching an object speaks what it is, and the word appears in a colorful animation. If the object appears in the text, the word in the text block is highlighted. This has served OM well for its series of Dr. Seuss and Berenstain Bear books, among others, and it's just as appropriate for Little Critter.