is applicationDidFinishLaunching the wrong place for setting an image for an UIImageView?

Question

I found out this:

applicationDidFinishLaunching (an delegate method of the UIApplicationDelegate Protocol) seems to be called BEFORE my views from the nib file are loaded completely. So I tried all the day to change an image of an UIImageView right after my app launched in the iPhone simulator, but nothing happened.

Then I wrote a little action method that I call with the press of a button. And then it happened: WORKS!

So the applicationDidFinishLaunching delegate method isn't really the right place for stuff that has to be done after the app is really "ready". I gues there's something better that waits for the nib to be loaded completely. but where? and what?

Answer 1

Hey until your views and their view controllers instantiated you can't modify their ui. However just for the sake of your problem you can always declare the uiimageview as a property of your app delegate class and initialize it in the appDidFinishLaunching event. But that's the worst practise. As on the iPhone which has limited memory always lazy load ie: only initialize objects when and just before they are actually required by your UI. So ideally you should be doing this in the viewDidLoad event of the view where you want to use this UIImageView.

applicationDidFinishLaunching is usually used for stuff like database file checks, opening database connection, populating global variables, any other application wide logic, checking for an available Internet connection etc

Answer 2

I gues there's something better that waits for the nib to be loaded completely. but where? and what?

For application specific things like global settings, preferences, etc., -appDidFinishLaunching is the right place.

For UIView specific things, you typically use the -viewDidLoad method in a UIVIewController subclass. It is pretty much the only place you are guaranteed that the nib file is loaded, the IBOutlets are initialized and the IBActions are attached.

This is difference from the Mac OS X world, where -awakeFromNib was the place to do it.