如何在applicationDidBecomeActive中确定它是否是最初的iPhone应用程序启动？

Question

how to determine in how to determine in UIApplicationDidBecomeActiveNotification whether it is the initial app launch?whether it is the initial app launch?

that is the initial start up of the application, as opposed to subsequent DidBecomeActive's due to the application being put in background and then to foreground (eg user goes to calendar then back to your app)

Answer 1

FWIW, the accepted answer tells you if the app has ever been launched before, not if the app is resuming from the background vs launching. Once the alreadyLaunched key has been set in preferences it will return YES when the app is launched in the future (vs resumed from background).

To detect if the app has resumed from the background you don't need to add anything to preferences. Rather, do the following in your app delegate implementation.

// myAppDelegate.m
//

@interface MyAppDelegate()
@property (nonatomic) BOOL activatedFromBackground;
@end

@implementation MyAppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.activatedFromBackground = NO;

    // your code
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    self.activatedFromBackground = YES;

    // your code
}

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    if (self.activatedFromBackground) {
        // whatever you want here
    }
}

@end

Answer 2

In your applicationDidFinishLaunching:withOptions: put this:

[[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"alreadyLaunched"];
[[NSUserDefaults standardUserDefaults] synchronize];

Then, in didBecomeActive :

if ([[NSUserDefaults standardUserDefaults] boolForKey:@"alreadyLaunched"]) {
    // is NOT initial launch...
} else {
    // is initial launch...
}

Answer 3

I used to use the method mentioned by @XJones. Then I realized it has a potential issue: if "the initial app launch" means to check in applicationDidBecomeActive whether it was called the first time since the app was launched! Because when app was relaunching the app (either through springboard, app switching or URL) all the above 3 delegate method will be called! So the safest way is to reset self.activatedFromBackground in applicationDidBecomeActive.