NSUserDefaults behaviour with app update

Question

I have a method in my iOS app that updates the application when detects when my server has a greater version for my app (a new ipa version). If the user wants to download it, th

Answer 1

They will not be removed. And will have old values.

if "HasLaunchedOnce" is used in the old version. use a new one and call it "HasUpdateLaunchedOnce".

Check both values and decide what do you want to do.

if (HasLaunchedOnce exists && HasUpdateLaunchedOnce not exists)
  // proceed

Answer 2

You could use an integer stored in NSUserDefaults with a version number hard-coded for each version of the app. If the integer is lower than the hard-coded version, prompt for updates:

NSInteger currentVersion = 3; // increment with each new version

if ([[NSUSerDefaults standardUserDefaults] integerForKey:@"HasLaunchedForVersion"] < currentVersion) {

    [[NSUserDefaults standardUserDefaults] setInteger:currentVersion forKey:@"HasLaunchedForVersion"];
    [[NSUserDefaults standardUserDefaults] synchronize];
    // This is the first launch for this version

} else {
    // App hasn't been updated since last launch
}