I have an application which allows customizing attributes such as background color, buttons, text (ie, titles), etc. In its current incarnation, viewDidLoad set the appropriate property on a UI widget by calling into a LookAndFeel class. LookAndFeel reads the user preferences.
Should each view perform a call into LookAndFeel, or should the Application fetch an attribute once and use the fetched value in all views? Is it OK to call getTitleColor once, hold it in the app delegate, and use it in every view?
That depends on how expensive your getTitleColor method is. If it's expensive, it should definitely be cached.
(Note: reading from a file or from NSUserDefaults could be considered expensive)