This is viable when your app works completely offline. As soon as it has a server to talk to things changes. It becomes rather expensive to maintain a server t

This is viable when your app works completely offline. As soon as it has a server to talk to things changes. It becomes rather expensive to maintain a server that has to support any previous client, or to support all the users who don't know how to update. In practice auto-update is the best default. Android lets you turn it off. On iOS I don't know.