Much of your application’s user interface may already be created by the time the PureMVC apparatus is initialized, and is therefore ready for mediation at startup. But there many situations that do not fit this easy approach. We will look at the major categories of problematic View Component life cycles in this chapter.
So far in the book, we have only covered mediation and interaction
with View Components that are in the display list by way of the main
application declaring a few top-level components, which in turn declare
other components, and so forth. In the case of
StoryArchitect, the application and its two
top-level components are mediated easily in the
PrepareViewCommand and receive
Events from all the subcomponents within.
However, the application also makes use of some pop ups, which
require an inherently different mediation strategy. They are transient
objects that are displayed and removed randomly throughout runtime. In
PopUpManager Singleton is
used to manage the display, centering, and removal of pop ups. If you want
to center the pop up over the application, you have to pass in a reference
to the application itself, which traditionally was accessed from another
Application.application. However that has been
deprecated in favor of
FlexGlobals.topLevelApplication. So if you have been working on a really large application where pop ups are created frequently throughout, you may see lots of warnings ...