Or you just do it the old fashioned way - teach them to read and give them books. If they can use an iPad they can read.
My 4 year old is just now learning to use a mouse, but she's been at a touchscreen for over 3 years.
She was used to iPads, but one day I gave her my Android tablet. She was upset at first because things are slightly different, but adjusted quickly. I was shocked at how fast she picked it up.
I had one family tell me they learned about five finger swipes from their 1 year old daughter.
When these are adapted for cartoons by Disney and others they are usually greatly sanitized. A parent who remembers those adaptations and thinks that is what they are getting when they get the original book versions is in for a surprise.
They are full of stories of people who are cruel and who cheat and abuse the weak and innocent, and in the end...that works out great for them and they get everything they wanted.