Question

Are there situations where a UIAlertView is better to use than a UIActionSheet? What are the typical scenarios where you would use one over the other?

I’m programming a navigation bar button to open a UIWebView in an external application, and at first I started programming a UIAlertView, then I thought that an action sheet might be better for this situation.

Are there any formal guidelines for which to use in different situations? Thanks.

Answer 1

From Apple’s iPhone Human Interface Guidelines:

Alerts, action sheets, and modal views
are designed to communicate different
things:

• Alerts give users important information that affects their use of
  the application (or the device).
  Alerts are usually unexpected, because
  they generally tell users about a
  problem or a change in the current
  situation that might require users to
  take action.
• Action sheets give users additional choices related to the action they are
  currently taking. Users learn to
  expect the appearance of an action
  sheet when they tap a toolbar button
  that begins either a potentially
  destructive action (such as deleting
  all recent calls) or an action that
  can be completed in different ways
  (such as a send action for which users
  can specify one of several
  destinations).
• Modal views provide more extensive functionality in the context of the
  current task or provide a way to
  perform a subtask directly related to
  the user’s workflow.