When Apple’s engineers designed iOS, they took the opportunity to pare away behaviors and usage patterns that were unnecessary in a modern operating system running on tightly controlled hardware. Two of the most obvious were quitting apps and restarting/shutting down the device. However, those capabilities had to remain accessible somehow. iOS apps can still freeze or otherwise freak out such that they can’t be used again until the user force-quits them, and iOS devices can still get into states where a restart is the only solution.
So Apple hid these troubleshooting features. You can force-quit a frozen iOS app by swiping up on its thumbnail in the App Switcher. Like so many other iOS gestures, that isn’t something you’d be likely to discover on your own, though Apple does document it. The Restart/Shut Down combination from macOS also made its way to iOS, though iOS muddles the terminology. (Apple’s documentation calls the process of pressing and holding the side or top button until the power-off slider appears “restarting,” even though it’s more like the Mac’s Shut Down command, given that it involves a power cycle. Indeed, in Settings > General, the command is Shut Down.) If your iOS device is frozen, you can also force-restart it with a variety of button incantations that are more akin to pressing and holding a Mac’s power button for 5 seconds to power it down abruptly.
But here’s the thing:
Force-quit iOS apps or restart iOS devices only to fix problems!
Although Apple doesn’t use the “force-quit” terminology, the company’s support documentation is crystal clear about how this action is necessary only when apps aren’t responding.
Despite warnings like this, and for reasons I don’t entirely understand, a surprisingly large number of people have gotten into the habit of force-quitting iOS apps. I once sat next to a guy on an airplane who would open an app like Messages, look at it briefly, and then force-quit it as soon as he was done reading the message. (Having to watch this nervous tic behavior for the first 20 minutes of the flight drove me batty, so I asked him if he would be interested in a tip that would improve his iPhone’s battery life and performance. Happily, he was.) I’ve even heard of people shutting down their iPads at the end of the day, much as they might have shut off a Macintosh SE/30 in 1990.
Yes, in the old days on the Mac, you wanted to quit inactive apps to free up memory and CPU power. And yes, in the old days on the Mac, it made sense to shut down every night to save power and to ensure that the Mac came up in a clean state the next morning. Neither of those behaviors is nearly as necessary as they used to be. The uptime command in Terminal reports that my 27-inch iMac has been running for (only) 12 days, and I have 20 apps open in the Dock, with over 700 processes showing in Activity Monitor. This is Unix!
In normal usage, I quit Mac apps when I can’t imagine when I would next use them, and I restart when Apple releases a macOS or security update. I only shut the iMac down when I travel for more than a few days because it uses so little power in sleep that starting it up from scratch might consume more (I tested it a while back, but there are a lot of variables). And that’s a desktop Mac—my MacBook Air spends every moment of its unused time in sleep.
Back to iOS. Because force-quitting apps and restarting or shutting down devices are necessary only to fix unanticipated problems, there are two notable downsides to engaging in such behavior as a matter of habit: reduced battery life and wasted time.
Force-Quitting iOS Apps and Restarting Hurts Battery Life
Why would these behaviors reduce battery life? Remember, iOS is a modern operating system that’s built on top of Apple’s proprietary hardware. Apple has put a great deal of effort into ensuring that iOS knows the best ways to manage the limited hardware resources within your iPhone or iPad. No one, possibly short of an iOS systems engineer armed with Apple’s internal diagnostic and debugging tools, would be able to outguess iOS itself on issues like memory usage, power draw, and CPU throttling.
When you invoke the App Switcher in iOS, you can swipe right to see all the apps you’ve used, possibly since you got your device. (The very first app in my iPhone 11 Pro’s App Switcher is Apple’s Tips, which I think came up automatically when I turned the iPhone on last year and hasn’t been touched since. It’s difficult to count apps in the App Switcher, but I probably have at least a hundred in there.) As the number of apps in the App Switcher should indicate, those apps are not necessarily running—they merely have run at some point in the past. They’re much more like the contents of the Mac’s Apple > Recent Items menu.
In normal usage, iOS devotes the lion’s share of CPU and memory resources to the app that you’re using. That’s sensible—the performance of that app is paramount. However, the next few apps in the App Switcher may also be consuming some CPU and memory resources. That’s because iOS correctly assumes that you’re most likely to return to them, and it wants to give you the best experience when you do. The screen shouldn’t have to redraw multiple times, Internet-loaded content shouldn’t have to update, and so on.
But the rest of the apps further back in the App Switcher? They’re just cardboard cutouts holding spots so you can open them again more easily than finding their icons on a home screen. In fact, switching to one of them is just like opening an app for the first time in weeks—iOS can do nothing to reduce the impact of launching it since it has to load the app’s code and data into memory, update its content from the Internet as necessary, and so on.
Launching apps in this way is expensive in terms of CPU and memory usage, and anything that forces iOS to spin up the CPU or move data around in memory consumes battery power. Apple knows that long battery life is essential for iPhones and iPads, so iOS tries hard to avoid those power-sucking app launches whenever possible.
But when you force-quit an app and open it again later, you’re preventing iOS from using its tricks to reduce CPU and memory usage—every launch is a fresh launch and consumes more battery power. For instance, once she learned in a TidBITS Talk discussion that force-quitting apps was a bad idea, reader Kimberly Andrew found that her iPad lasted 4 days on a single charge instead of requiring nightly recharging. Your experience may not be so dramatic, but if you let iOS manage your device’s resources, you’ll get the best possible battery life for your usage patterns.
What about restarting your device? It provokes the same hit to battery life, in spades, since restarting forces iOS to launch everything from scratch, along with a wide variety of background tasks that you never see. Luckily, I don’t see people restarting nearly as often as I see them force-quitting apps.
Force-Quitting iOS Apps and Restarting Wastes Your Time
From my explanation above, it should be clear that preventing iOS from managing CPU and memory resources by force-quitting apps will also reduce performance. It may be less obvious than it would be on the Mac, where launching an app might take a few seconds but switching to a running app is instantaneous, but it’s a similar performance hit for no benefit.
The more important CPU cycles to preserve, however, are between your ears. Any time you force-quit an app that’s behaving normally, you’re doing something that’s completely unnecessary. It wastes your time both quitting the app and launching it again if you want to use it again soon. You can’t even use the App Switcher as a shortcut for finding the app’s icon on a home screen.
Even worse is thinking that there’s any benefit to shutting down an iOS device when you’re not using it for a bit. iOS is not quick to restart—it took 68 seconds to power down my iPhone 11 Pro and wait for it to come back up. That’s a long time to stare at the white Apple logo. Sure, you could do something else during that time, but again, it’s completely unnecessary, wasting your time to shut down, start up, and deal with slower apps for a bit. Don’t bother.
Besides, surely you have better things to think about.
Force-Quitting and Restarting Are Useful Problem-Solving Tools
Let’s keep some perspective. As much as force-quitting iOS apps and restarting devices unnecessarily reduce battery life and waste your time, those actions won’t actually hurt anything. They’re bad habits, but they aren’t like unceremoniously unplugging a Mac’s external drive, where you could lose or corrupt data if files were open for writing.
There are times when iOS apps freeze or refuse to refresh or otherwise misbehave in ways that you can’t otherwise fix. That’s when a force-quit is absolutely the thing to do. Similarly, I’ve seen situations where my iPhone inappropriately reported No Service or was just being weird, and a restart was a quick and easy fix. Don’t be shy about restarting if your device isn’t working as it should, and of course, if the screen is frozen or the entire device is unresponsive, look up and invoke those force-restart button incantations.
Finally, there have been a few reasons in the past to engage in these behaviors, although they shouldn’t be necessary any longer. Most notably, early mapping apps weren’t always good at ending GPS-based navigation, which is a significant power draw, so for a while, it was worth force-quitting such apps to ensure they didn’t continue to navigate in the background. I haven’t seen that problem in years, but it’s not inconceivable it could crop up again with some app. In general, if you’re interested in preventing apps from doing things in the background, block them in Settings > General > Background App Refresh.
Plus, if you’re dealing with an iPhone with a weak battery, for instance, it might make sense to shut it down entirely to preserve battery life if you don’t plan to use it for at least a few hours. It’s impossible to know when the extra power draw from a cold boot would be greater than the power consumed in sleep (you’d also definitely want to enable Low Power Mode, put it into Airplane Mode, and disable Wi-Fi and Bluetooth), but at some point, shutting it down would be better.
In general, then, let force-quit and restart be problem-solving techniques you use only as needed, and if you’ve gotten in the habit of force-quitting or restarting regularly, give your iPhone a break.