How can I know whether app is terminated by user?
(Double-clicking Home button and press red minus '-' button)
I need sample or pseudo code...
Sometimes you do get the UIApplicationWillTerminateNotification (you can also implement the applicationWillTerminate: method in your app delegate), but it's not guaranteed that you do get any notification at all in this case. So don't rely on it.
You won't receive the notification if your app is "suspended", that is it is in background but not running. In the suspended case you simply get killed with the non-catchable SIGKILL. Same for when you get killed due to out-of-memory.
From the documentation for applicationWillTerminate: (emphasis mine):
For applications that do not support background execution or are linked against iOS 3.x or earlier, this method is always called when the user quits the application. For applications that support background execution, this method is generally not called when the user quits the application because the application simply moves to the background in that case. However, this method may be called in situations where the application is running in the background (not suspended) and the system needs to terminate it for some reason.
When user kills the app:
- (void)applicationWillTerminate:(UIApplication *)application{
}
Application will enter inactive state:
- (void)applicationWillResignActive:(UIApplication *)application
{
NSLog(#"Application Did Resign Active");
}
User pushes Home button:
- (void)applicationDidEnterBackground:(UIApplication *)application
{
NSLog(#"Application Did Enter Background");
}
Try this:
- (void)applicationWillTerminate:(UIApplication *)application
{
/*
Called when the application is about to terminate.
Save data if appropriate.
See also applicationDidEnterBackground:.
*/
}
You should implement the method above in your class that implements UIApplicationDelegate
Some more notes: that method won't be called if you are stopping your app via Xcode (stop debug button). So be patient when testing.
Also there is this:
- (void)applicationDidEnterBackground:(UIApplication *)application {
}
Could be helpful if you want to know did it enter background ;)
Related
I have a Tab bar app with 3 view controllers and I use "viewWillAppear" to detect which view is opend.
When I close the app, it still works "in the background" and when I open the app again "viewWillAppear" is not detecting this opening.
Is there any other option to detect this opening? Thanks
You can observe the UIApplicationWillEnterForegroundNotification or implement applicationWillEnterForeground: in your app delegate.
Firstly, You should see the necessary delegation method in UIApplicationDelegate
When you close application that currently open, It will call this method:
- (void)applicationDidEnterBackground:(UIApplication *)application
After the application has been closed but still in dock, you open them again. In the transition state before entering the application, It will call this method:
- (void)applicationWillEnterForeground:(UIApplication *)application
When the application completely presented on previous state before you closed them. It finally call thid method:
- (void)applicationDidBecomeActive:(UIApplication *)application
If you would like to do something in viewWillAppear you should implement in applicationDidBecomeActive to send some message to your current view or other to do what do you want to do after application became actived.
When your app is resumed from the background, it will receive the applicationWillEnterForground: method. It'll get the applicationDidEnterBackground: when it is suspended too.
- (void)applicationWillEnterForeground:(UIApplication *)application {
NSLog(#"app will enter foreground");
[viewController refresh:NULL];
}
i think this will work.
write this in your app delegate
I want to design it so that if the user clicks home button then comes back to the application, the application will recognize that action and generate a message for the user to see (e.g., welcome back). I guess I should modify appdelegate for this, but I don't know how to go about coding it...can anyone lend a hand?
Whenever app wake up from background.. it come in this delegate in app delegate -
- (void)applicationWillEnterForeground:(UIApplication *)application
{
/*
Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
*/
}
You can show a msg to user in this delegate
Also check these delegates -
- (void)applicationWillResignActive:(UIApplication *)application
{
/*
Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
*/
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
/*
Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
*/
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
/*
Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
*/
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
/*
Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
*/
}
- (void)applicationWillTerminate:(UIApplication *)application
{
/*
Called when the application is about to terminate.
Save data if appropriate.
See also applicationDidEnterBackground:.
*/
}
When the iPhone application is running in background and it receive a remote notification. So it will execute the didReceiveRemoteNotification call back. In that I am going to push to a new UIViewController. But before that its noticed that its calling the applicationWillEnterForeground callback.
In that I am also doing some location update using a modal dialog. So when this notification arrives this both scenarios happens and the app is getting crashed. So is there any way to block the applictiaonWillEnterBackground processing on remote notification. As the moment is little bit hard cos this processing is done after applicationWillEnterBackground controller.
Thank you.
The callback application:didReceiveRemoteNotification: should only be invoked when the application is running in the foreground. When running in the background you should instead get a call to application:didFinishLaunchingWithOptions:.
Since you are asking the question and also using core location it might be that application:didReceiveRemoteNotification: is called when the application is in the background but I would think that would be a bug. At least according to Apple's documentation.
Anyway, NO, you can't block applicationWillEnterForeground:. Without knowing exactly what you are doing in the different callbacks I would recommend that you set a flag in applicationWillEnterForeground: if you are doing something there and then check that flag in application:didReceiveRemoteNotification:
- (void)applicationWillEnterForeground:(UIApplication *)application {
if (somehingHappend) {
somethingHappended = YES;
}
}
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {
if (!somethingHappened) {
// push your view controllers or whatever
}
}
Where somethingHappened is a BOOL defined in the same class as an ivar.
The applicationWillTerminate delegate method is not getting called in iOS 4.0
When I hit the Home button I am seeing the applicationWillResignActive and applicationDidEnterBackground delegate methods getting called.
- (void)applicationWillResignActive:(UIApplication *)application
{
NSLog(#"Application Did Resign Active");
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
NSLog(#"Application Did Enter Background");
}
And when I double Tap the Home button and again launch the Application the i find the applicationWillEnterForeground and applicationDidBecomeActive delegate methods are getting called.
- (void)applicationWillEnterForeground:(UIApplication *)application
{
NSLog(#"Application Will Enter Foreground");
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
NSLog(#"Application Did Become Active");
}
But I want to know when the applicationWillTerminate delegate method will be called , where I do some DB/file backup routines.
- (void)applicationWillTerminate:(UIApplication *)application{
}
I even tried to hit the minus sign and deleted the App running in the Background , but still it did not call any delegate method.
Any Ideas ???
From the iPhone Application Programming Guide:
Even if you develop your application using iPhone SDK 4 and later, you must still be prepared for your application to be terminated. If memory becomes constrained, the system might remove applications from memory in order to make more room. If your application is currently suspended, the system removes your application from memory without any notice. However, if your application is currently running in the background, the system does call the applicationWillTerminate: method of the application delegate. Your application cannot request additional background execution time from this method.
So yes, applicationWillTerminate: will generally not be called very often in iOS 4. If you have to save data, you should do so in both applicationWillTerminate: and applicationDidEnterBackground:.
The WWDC 2010 Session Adopting Multitasking on iPhone OS (Part 2) explains the application state transitions extremely well.
I got one solution for terminating apps when user hits the Home button in iOS4.
This will call the applicationWillTerminate delegate method instead of entering into background process.
Open your info.plist file
Add The Key UIApplicationExitsOnSuspend
Set the new key to YES
Actually you can also use this step to do so.
Open your info.plist file
Add The Key -> Application does not run in background
Set this key value to YES
Is it possible to logout when the iPhone Home button is pressed?
In the current iPhone API, it is impossible to "hijack" any of the hardware presses. You will be notified of certain events however. If you are wishing to call some function (logout) when the user exits the app by pressing the home button, you can implement the
- (void)applicationWillTerminate:(UIApplication *)application {
....
}
method in your Application Delegate. This method is called when the app is about to terminate through a phone-call, manual exit, or any other reason. You should be advised, however, that anything here better be very short execution and non-essential, as Apple does not guarantee that it will run through the whole method before terminating the application
For iOS 4.0 + however you will have to implement logout in this method as well
- (void)applicationDidEnterBackground:(UIApplication *)application