CHAPTER 2
Container Views
2-48 How Views Work
displayed, causes the normal view of the tapped name to appear; but
tapping the right part of the line, where the telephone number is displayed,
initiates a phone call.
If an application spends more than a few seconds preparing an overview, it
should display a status slip with a message such as “Preparing overview...”
(see “Status Slips” on page 2-20).
Scroll and Overview in an Overview 2
An overview should respond to the universal scroll arrows and the Overview
button. When a user taps a scroll arrow, your application should scroll all the
currently visible items out of view except the last item. After scrolling, there
should always be one item still visible from before scrolling. When scrolling
the last item into view, the application can leave more than one item still
visible from before scrolling so that the overview remains full of items; users
can’t do anything with empty space in an overview.
When a user taps the Overview button, the overview goes away and the
detail view reappears, showing the same item as before the overview
appeared. Thus, repeatedly tapping the Overview button switches back and
forth between the overview and the detail view. Avoid any temptation to use
the Overview button to zoom up or down multiple levels of detail or to step
through a hierarchy of views, because the user can easily become confused
about whether the next tap will go up or down.
An application that doesn’t have a list-style overview can use the Overview
button to toggle a view between two levels of detail or magnification. If there
are more than two levels of zooming, the Overview button must always
toggle between the same two levels, preferably the biggest and smallest
levels. For access to other levels, use another type of control described in
Chapter 3, “Controls.” For example, you could use a button on the status
bar—the Show button or a special Zoom button or zoom-looking picture
button. For completeness, the magnification control should provide access to
all levels, including the two levels controlled by the Overview button.