- Not running - terminated app or one that’s never been launched.
- Inactive - in the foreground but not receiving events
- Active - the usual state of an app when it’s been used
- Background - the app is not on the screen but still executing code
- Suspended - the app is not on the screen, it’s still resident in memory but not executing code
Here's the most common misconception about iOS multitasking
Ever since iOS got multitasking in version 4.0, many have complained that it’s not the “real” multitasking we see on other mobile platforms and most fingers are usually pointed at Android as an example. It’s true that the way Apple has implemented multitasking is different, and it’s also true that the majority of users would agree that it’s very elegant. There’s one misconception about the way it works, though, that keeps popping up and you can even hear it from Apple “Geniuses.”
The tip that is often wrongly given is that you need to delete apps from your multitasking bar to free up memory. So for example if your phone has a ton of apps listed in the multitasking bar on the bottom, the wrong suggestion is that it’d get bogged down and you need to go and manually remove apps to free up memory. Mac and iOS developer Fraser Speirs clarifies:
“Wrong. Wrong. Wrong. Wrong. Wrong. Wrong. Wrong. There are caveats to this but anyone dispensing the advice above is clearly uninformed enough that they will certainly not be aware of these subtleties.”
Why is it wrong, though? Digging deeper into the way iOS handles multitasking, you’d notice that there are five states in which apps are:
Now, here’s the crux of iOS multitasking. When you hit the home button on your iOS device, the application goes from Active to Background. Then in a matter of seconds, it usually jumps from Background to Suspended, so it’s not using processing power, but it’s still in the memory.
You shouldn’t worry about that, though, because if you happen to launch another memory intensive application, iOS will automatically understand that it needs all the memory that it can have and will kill apps into Not running state.
You don’t need to manually delete anything because iOS handles this for you and that’s the beauty of iOS multitasking.
What’s even more important - what you see in the multitasking bar is not a list of running applications. It’s a list of most recently used apps, which could be inactive (Not running).
So bottomline is, you don’t need to bother clearing apps from the multitasking bar. Apple has already taken care of this, and you’d be just wasting your time. There are some exceptions in very rare cases, but in the general case, you’d be fine not caring for the multitasking bar. Hit the source link below for the brilliant and detailed explanation of Fraser Speirs.