I’m always thinking about how to make my apps run and load faster. It’s incredibly important, especially to your users. Earlier today I ran across a Twitter conversation (https://web.archive.org/web/20131003185836/http://twitter.com/flyosity/status/239044820394471424) between a few guys I consider to be top notch: Sam Soffes, Jake Marsh and Mike Rundle. They were discussing best practices for getting your app loading speed down.
There’s a great article by Brent Simmons in which he discusses his methods for making Glassboard 2.2 load faster, it’s available here: http://inessential.com/2012/08/23/an_iphone_app_startup_performance_techni
Mike also pointed out Sam’s code from Cheddar:
https://github.com/nothingmagical/cheddar-ios/blob/master/Classes/CDIAppDelegate.m#L68
In his didFinishLaunching method, he performs only the most essential tasks and puts everything else in an async queue to run in the background without blocking the main thread. This frees the app up to get the UI and other elements rolling.
On top of this optimization you can do a few things to make your app APPEAR to load faster, namely, a proper Default.png. It’s easy to fall into the temptation to create a cool splash screen but it’s my belief a good Default.png will help “lead” your user into the app and reduces the amount of perceived load time. Apple recommends (http://developer.apple.com/library/ios/#DOCUMENTATION/iPhone/Conceptual/iPhoneOSProgrammingGuide/App-RelatedResources/App-RelatedResources.html) you use a screenshot of your initial view with the text and buttons removed. Here are a few examples of good Default.pngs:
WordPress
Colloquy
Cheddar
In reality, Default.png will only show for a second or so but when properly done, in conjunction with a few of the techniques mentioned by the other guys, can help make your app load feel snappier.