When is applicationwillenterforeground called

In almost every app there is some code that you want to run each time a user opens the app. For example you want to refresh some data or track that the user opened your app.

But either of these methods is not ideal for this case:. It is only called when the app was in the background and then enters the foreground. At first launch the app is not in the background state so this methods does not get called. That happens everytime the user opens Control Center, Notification Center, receives a phone call or a system prompt is shown e. So if you put your code in applicationDidBecomeActive it will not only get called when the user opens the app but also in all those cases mentioned above.

So to really run your code only when your user opens the app you need to keep track of the app's state. You would probably implement something like this:.

This is not a big problem, but it is not a very elegant approach. And you have to set the inital value of didEnterBackground to true to run your code after the first launch see above , even if the app never has been to the background. Call me picky, but I don't like that. RxAppState to the rescue! With RxAppState you can simply do the following:. This runs your code whenever the user opens the app. If your application supports background execution, called instead of applicationWillTerminate: when the user quits.

Called as part of transition from the background to the inactive state: here you can undo many of the changes made on entering the background. 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.

The seven most important application delegate methods a developer should handle are:. Method called when the launch process is initiated. This is the first opportunity to execute any code within the app.

Method called when the launch process is nearly complete. Since this method is called is before any of the app's windows are displayed, it is the last opportunity to prepare the interface and make any final adjustments. Once the application has become active, the application delegate will receive a callback notification message via the method applicationDidBecomeActive.

This method is also called each time the app returns to an active state from a previous switch to inactive from a resulting phone call or SMS. There are several conditions that will spawn the applicationWillResignActive method. Each time a temporary event, such as a phone call, happens this method gets called. It is also important to note that "quitting" an iOS app does not terminate the processes, but rather moves the app to the background.

This method is called when an iOS app is running, but no longer in the foreground. In other words, the user interface is not currently being displayed.