Detecting the first launch of an app with previous

问题:

I would like to update an app to add a tour on first launch. I would ordinarily handle this with some kind of NSUserDefaults key. However, there are pre-existing existing versions of the app already released.

How can I trigger some behavior on first launch of the app, but only for fresh installs and not for the first launch after an update?

回答1:

you can check app version via web service. and warn users to update the app. And this case, internet connection required.

回答2:

On launch, check for the existence of a file/persistent setting with a name unique to the currently running version. If it's not there, show the tour, then touch the file/create the persistent setting.

回答3:

The best approach I can identify so far is to first release a version without the tour but that does record some kind of flag to NSUserDefaults. Then I can hope that most existing users will update and use the app before I launch a second update including the tour.

I can combine this with @rmaddy's suggestion to look for any other previously existing settings that might have been written to increase my coverage.

This is obviously far from ideal.

回答4:

The easiest way is to save the current version using NSUserDefaults:

if (![[NSUserDefaults standardUserDefaults] objectForKey:@"app_version"] || [[[NSUserDefaults standardUserDefaults] objectForKey:@"app_version"] integerValue] < [[[NSBundle mainBundle] objectForInfoDictionaryKey: @"CFBundleVersion"] integerValue]) {
    // new version detected!
    [[NSUserDefaults standardUserDefaults] setObject:[[NSBundle mainBundle] objectForInfoDictionaryKey: @"CFBundleVersion"] forKey:@"app_vervion"];
}

EDIT Added check for user defaults existence for first update containing this functionality.

EDIT II I now understood what you really want. You'll need almost the same code I wrote:

if (![[NSUserDefaults standardDefaults] boolForKey:@"tour_done"]) {
    // present tour and that call:
    // [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"tour_done"];
    // [[NSUserDefaults standardUserDefaults] synchronize];
}