I've got a popup asking for users to rate the app after it's been opened a certain nr of times. However, since apps run in the background on iOS when exited rather than being shut down, it's hard to gauge how many times is appropriate before the nagging begins. Don't want it to be too soon, but not too late either. So my question is: how long does an app stay in the background before it's forced to close? I'm thinking of using the "Application does not run in the background"-attribute in the plist to force it closed each time a user exits it, since the app is a very fast starter and quickly resumes to where the user left off.