Understanding multitasking on iOS: Should you quit apps?

Do you need to close your iOS apps after each use? Cory Bohon takes a look at multitasking on iOS and answers this iOS 4-old fable.


Multitasking with iOS

Apple first introduced multitasking to iOS devices with the introduction of iOS 4. Multitasking has largely remained the same since those days on iPhones and iPads. The word "multitasking" as it relates to iOS is used very loosely, and this loose definition has led to confusion among users of iOS devices and created various myths along the way. In this article, we'll answer the iOS 4-old fable: Do you need to close your iOS apps after each use? Let's find out.

Before we get into the ways that multitasking is used on iOS, let's first visit how to use multitasking. To quickly switch between apps on your device, Apple has devised a multitasking view (Figure A) that can be accessed by double-clicking the device's home button.

Figure A


Figure A

This multitasking view shows all of your recently-used applications.

Contrary to some publicly-available misconceptions, the applications shown in this view are not necessarily applications that are running. Rather, this just shows those applications that have recently been used. You can remove applications from this section by tapping on the screenshot of the app and "flicking" them upwards towards the top of the screen. If the application is backgrounded, then doing this will terminate the app.

That being said, there are some states that allow applications to run in a multitasking environment on iOS. Let's take a look at those states and how you can tell if an application is currently running in the background.

Background App Refresh

Background App Refresh is a new technology that was released in iOS 7 to allow applications to perform brief tasks when a push notification is sent to the device. iOS can automatically wake the app and allow it to perform a quick task. This task is limited to a 30-second window, after which the application will automatically be shuttered by the operating system to preserve battery life. The Background Refresh settings give you a per-application ON/OFF switch (Figure B) for selecting which apps can be sent a push notification to wake and perform a task.

Figure B


Figure B

The Background Refresh settings.

iOS will automatically learn from user patterns and disable Background App Refresh on those applications that aren't frequently opened and used. If you have battery concerns for a particular application, you can manually revoke Background App Refresh access on a per-app basis by navigating to Settings | General | Background App Refresh.

In this settings view, you can easily disable Background App Refresh across all apps by sliding the switch to OFF for this section. You can also slide the switches to OFF for each of the applications listed in the section to disable the feature for only those applications. Only apps that support Background App Refresh will be listed in this section. Applications that have a small location icon next to the switch are apps that can access your location information whenever they are powered up by the Background App Refresh service.

Backgrounded music, VoIP, and navigation

The oldest background services that Apple put into place are background music streaming, VoIP service, and turn-by-turn navigation. If an application that you're using falls into one of these three categories, it can have the option to keep running long after you've pressed the home button.

If one of these applications are running, however, you will know it from the following signs:

  • If the application has music backgrounding, then the music will keep playing after you exit the application
  • If the application has navigation backgrounding, then a small blue "Touch to return to Navigation" bar will appear in the status bar area (Figure C)
  • If the application is actively using your GPS location, then a solid color location icon will appear beside of the battery icon in the status bar
  • If the application has VoIP backgrounding, then a red double-height status bar will appear with the name of the application in use appearing in a small label
Figure C


Figure C

An example of navigation backgrounding.

With the status bar colors, you can know immediately what type of application is being backgrounded: The top (blue status bar) means that a navigation app is currently using the GPS location actively; the bottom (red status bar) shows that a VoIP application is actively using the microphone and speaker for Internet telephony.

You can manage the applications that have access to use the GPS location of your device in the background by navigating to Settings | Privacy | Location Services and disabling location services on a per-app basis.

Note that VoIP applications (like Skype) can receive calls while in the background and will not display the red status bar while in this backgrounded state.

Apple background services

Apple has special backgrounding services that only can be used by them to do special things. For example: Photo Stream uploads, application downloads and updates from the App Store or Newsstand, Automatic iTunes content downloads, iTunes Match updates, Checking email, and iCloud Restores. All of these services, when in use, will display a network activity spinner next to the network icons in the status bar.

Another special background service that Apple uses is background Over The Air (OTA) iTunes syncing. Whenever a small syncing spinner icon appears in the status bar, then the device is currently syncing, either wired or wirelessly with iTunes.

Bottom line: Do I need to close those apps?

If the application that you are using doesn't support Background App Refresh (meaning that it's not listed in that settings section), then as soon as you press the home button, the application is automatically terminated -- assuming it isn't using background music streaming, VoIP, or navigation backgrounding. You don't need to close applications out of the multitasking tray unless they are currently being backgrounded and you no longer wish to keep them running.

We've heard some folks say that you should close every application from the multitasking tray after you're done using it. That's simply not required. However, you may want to quit applications that are backgrounded if you're running low on power resources.

Being aware of which applications can background themselves can save on battery life and on the data usage for your cellular plan.



By Cory Bohon

Cory Bohon is an indie developer specializing in iOS and OS X development. He runs a software company called Cocoa App and is also a developer at MartianCraft. He was introduced to technology at an early age and has been writing about his favorite te...