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Tuesday 3 November 2015

Application States

Hi,

We are about to learn all different states of an iOS app.
The system moves your app from state to state in response to actions happening throughout the system. For example, when the user presses the Home button, a phone call comes in, or any of several other interruptions occurs, the currently running apps change state in response.Following are the app states,

1. Not running : The app has not been launched or was running but was terminated by the system.

2. Inactive : The app is running in the foreground but is currently not receiving events. (It may be executing other code though.) An app usually stays in this state only briefly as it transitions to a different state.

3. Active : The app is running in the foreground and is receiving events. This is the normal mode for foreground apps.

4. Background : The app is in the background and executing code. Most apps enter this state briefly on their way to being suspended. However, an app that requests extra execution time may remain in this state for a period of time. In addition, an app being launched directly into the background enters this state instead of the inactive state.

5. Suspended : The app is in the background but is not executing code. The system moves apps to this state automatically and does not notify them before doing so. While suspended, an app remains in memory but does not execute any code.

When a low-memory condition occurs, the system may purge suspended apps without notice to make more space for the foreground app.



fig. Change of App States


Most state transitions are accompanied by a corresponding call to the methods of your app delegate object. These methods are your chance to respond to state changes in an appropriate way. These methods are listed below, along with a summary of how you might use them.