Prevent Splash Screen from showing after returning from background
In my experience, this is something handled by iOS (I'm going with experience because I've not seen any documentation about this). If the OS can restore the application state nice and quickly, it'll display a screenshot of its previous state while that state is restored.
However, if something will delay the process, such as the app not being in the background properly yet (such as during rapid task switching), or if something else predictable will delay the startup, then it reverts to the splash screen (instead of the screenshot), to ease the user experience.
Short answer: it's out of your hands.
Well, apparently this question wasn't very clever to begin with :) This "problem" only happens in the Simulator. When Debugging on the device itself, it works as expected.
No harm done. Thanks everyone who tried to help! :)
I know that this question is marked an "answered" - but the reality is that the answer was not correct in my case and I want to share.
I initially came to the conclusion that the most accurate answer above was from QueyJoh - "this is something handled by iOS ... Short answer: it's out of your hands."
However after experimenting I managed to locate the issue as being entries in my info.plist file controlling the status bar. Specifically I had entries for "UIStatusBarHidden" and "UIStatusBarStyle".
Removing these entries from my plist file immediately stopped my app from showing the Splash screen when switching away from my app and back again.
Problem solved.
Matthew