That is, the reason the user picked up the device to run your app and the end result they wanted, was perfectly and intuitively accessible to the user without thought of what the app can do and how that might translate into what they wanted to do. Invisible UI, intuitive user experience, knowing how to use an app the first time, etc, etc; they all require the same thing: for the users intent and the applications features to be one.
That’s the key to a great iOS app: remove the translation in the user’s head from what they want to what the app actually does. What a great way of explaining what an “intuitive user experience” means.