What will be a good UI design for the iPhone app wise notification

Question

I have a background thread working on collecting data, once that's ready, I want to send out a global notification such that all the views can get it. That's easily achievable logically. But visually, I want the user, while on any view of the app, got notified as well so he can prompted to take some action - e.g., ignore or reload - once see the prompt.

Now the question is - what'll the best design for this prompt? a popup dialog definitely serves the purpose, but it's annoying of it pops up frequently; a top down notification or a bottom up notification is better - but can I do that globally? and I have a TabBar at the bottom, so the top down might be better, will overlay the navigation bar be a good idea for that purpose?

any other suggestions?

Answer 1

iOS has a defined UX guidelines, I would go with them.

This is what it has to say about modals:

Modality is most appropriate when:

• It’s critical to get the user’s attention.

• A task must be completed (or explicitly abandoned) to avoid leaving the user’s data in an ambiguous state.

If you feel your situation relates to these terms, then a modal (an alert) is the appropiate way to go. If it doesn't relate, then go for another option, such as the mentioned Notification Center.

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On a side note, I would like to address the "popups are annoying" myth by quoting an extract of the document:

People appreciate being able to accomplish a self-contained subtask in a modal view, because the context shift is clear and temporary.