detect my apps been killed - iphone

Question

I have built a simple apps that connect to a sqlite database, and the app uses storyboards for UI. On first time, it will throw up a login view. If my authenticate was successful, I change my status in the sqlite database to 1. By default, it is 0. After login, I can use the app.
For example if I kill the app, how can I know my app has been killed? I need to change the status become default again. so whenever I click on the app again, I have to sign in again.
Any idea how to do this? thanks.

Answer 1

Your application delegate implements several methods which handle state changes in your application. From the UIApplication.h header.
- (void)applicationDidFinishLaunching:(UIApplication *)application;
- (BOOL)application:(UIApplication *)application willFinishLaunchingWithOptions:(NSDictionary *)launchOptions NS_AVAILABLE_IOS(6_0);
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions NS_AVAILABLE_IOS(3_0);
- (void)applicationDidBecomeActive:(UIApplication *)application;
- (void)applicationWillResignActive:(UIApplication *)application;
- (void)applicationWillTerminate:(UIApplication *)application;
You can implement whichever methods are relevant, in this case the applicationWillTerminate method to change state. Alternatively, always throw up a login view in applicationDidBecomeActive. (This doesn't, however solve the issue updating the database. If the database is local, there's no problem, simply change the database before resigning or terminating. The challenge here would be if your database lives on a server. Although it might bot be an issue, I could see connection timeouts affecting the integrity of the remote values.)
These methods are added to your project automatically in your application delegate, which can be found in the AppDelegate.h & AppDelegate.m files.
For a complete explanation, have a look at the UIApplication Delegate protocol reference.

Answer 2

You can perform close down actions in,
- (void)applicationWillTerminate:(UIApplication *)application
{
// Log out?
}
You can also do the same if your app isn't killed but just gets suspended, such as during an incoming call,
- (void)applicationWillResignActive:(UIApplication *)application
{
// Log out?
}
or,
- (void)applicationDidEnterBackground:(UIApplication *)application
{
// Log out?
}
Alternatively, on resume,
- (void)applicationDidBecomeActive:(UIApplication *)application
{
// Log in?
}
or,
- (void)applicationWillEnterForeground:(UIApplication *)application
{
// Log in?
}

Answer 3

You can't detect if you app was killed, since the process of you app gets killed by the system and no code is called to inform your app that it has been killed.
What you want is to set te some kins of boolean in :
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
Since this is called if you restart the app after it has been killed.
For the other states seen the answer by Moshe

Answer 4

EDIT
use the delegate methods
such as:
applicationWillResignActive