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From: Jolly Roger <jollyroger@pobox.com>
Newsgroups: misc.phone.mobile.iphone
Subject: Re: Troubleshooting on an iPad.
Date: 20 Sep 2024 16:40:39 GMT
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On 2024-09-20, Bernd Froehlich <befr@eaglesoft.de> wrote:
> On 19. Sep 2024 at 10:06:15 CEST, "John Hill" <watcombeman@yahoo.co.uk>
> wrote:
>
>> My son has has asked me:
>> 
>> My iPad is getting slower and slower to the extent that it’s making
>> some applications difficult to use. I could try shutting down or
>> restarting but my perception is this is a recurring issue. Is there
>> any known memory or process monitoring on the iPad to see if I have
>> an app that is misbehaving?
>> 
>> I know of none, but that doesn't mean there isn't anything. cAnd if
>> there is I assume it would apply equally to the iPd and iPhone.
>> 
>> Any suggestions? I have suggested a power down and restart, and he
>> will try that for starters.
>
> You could try if closing all running apps helps. (AFAIK a restart
> won´t do that).

No, restarting does close all apps. 

Many people have the mistaken impression that manually force quitting
iOS apps is a good thing to do, but in reality force quitting apps makes
the device work harder and use more battery the next time those apps are
used. The OS manages apps in a much more efficient manner than you can.
The only reason you should be thinking about force quitting apps is if
you are troubleshooting a problem.

The operating system that runs on Apple’s mobile devices automatically
suspends apps when you switch away from them, and automatically resumes
them when you switch back to them later. Suspended apps do not use CPU
or battery while suspended. Only a few certain types of apps are allowed
to run in the background in iOS, and only on a limited basis.

Apps can exist in any of five states of execution:

- not running: the app has been terminated or has not been launched
  since the device was restarted
- inactive: the app is in the foreground but not receiving events (for
  example, the user has locked the device with the app active)
- active: the normal state of an app while in use
- background: the app is no longer front-most but is still executing code
- suspended: the app is still resident in memory but is not executing
  code

When you switch away from an app, the OS moves the app from active to
background state. Most apps usually then go from background to suspended
in a matter of seconds. Suspended apps remain in the device’s memory
temporarily so they can resume more quickly if you switch back to them;
but they aren't using processor time and they’re not sucking battery
power.

If you launch a memory-intensive app, such as a game, the OS will
automatically purge some suspended apps from memory and move them to the
not running state to free up memory for the memory-intensive app you
launched. Those previously suspended apps will be completely removed
from memory and will launch from scratch the next time you tap their
icon. Well-written apps automatically save their state before they are
suspended and restore it when they are launched again.

Most apps do not run in the background. The OS gives all apps a default
five seconds after you switch from them to wrap up operations in
preparation for being suspended. After this five-second period, the OS
automatically suspends the app’s operations.

If an app developer believes they need further background processing
time, they can design the app to declare a specific task as background
task which allows the task to run for up to about ten minutes of
background running time before it is forcibly suspended by the OS.

So all apps get five seconds of background execution allowing them to
clean things up when you switch away from them. And some apps can
request a ten-minute extension for longer processing tasks. But there
are a small number of apps that genuinely need to run in the background,
either indefinitely or periodically.

The OS restricts this indefinite/periodic background activity to exactly
five kinds of apps:

- apps that play audio while in the background state
- apps that track your location in the background (for instance a
  turn-by-turn GPS navigation app needs to be able to give you voice
  prompts even if another app is active)
- apps that listen for incoming voice-over-IP (VOIP) calls (for instance
  Skype needs to be able to receive incoming calls while the app is in
  the background)
- apps that you allow to refresh their data in Settings > General >
  Background App Refresh
- apps that receive continuous updates from an external accessory in the
  background

Generally you already know if you are using one of these types of apps.
And all well-written apps in the above categories become suspended when
they are no longer performing the task at hand.

> iPad OS SHOULD take care of memory by itself, but I have encountered some
> situations where closing all apps helped.

Force quitting a particular misbehaving app may solve a particular
problem, yes.  But force quitting all apps on a regular basis isn't
necessary and does more harm than good.

-- 
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JR