By John Gruber
Mobelux designs, builds, and brands award winning digital products, all under one roof.
The single biggest misconception about iOS is that it’s good digital hygiene to force quit apps that you aren’t using. The idea is that apps in the background are locking up unnecessary RAM and consuming unnecessary CPU cycles, thus hurting performance and wasting battery life.
That’s not how iOS works. The iOS system is designed so that none of the above justifications for force quitting are true. Apps in the background are effectively “frozen”, severely limiting what they can do in the background and freeing up the RAM they were using. iOS is really, really good at this. It is so good at this that unfreezing a frozen app takes up way less CPU (and energy) than relaunching an app that had been force quit. Not only does force quitting your apps not help, it actually hurts. Your battery life will be worse and it will take much longer to switch apps if you force quit apps in the background.
Here’s a short and sweet answer from Craig Federighi, in response to an email from a customer asking if he force quits apps and whether doing so preserves battery life: “No and no.”
Here, from the official support document on forcing applications to close, is Apple’s own advice on when to use this feature:
When you double-click the Home button, your recently used apps appear. The apps aren’t open, but they’re in standby mode to help you navigate and multitask. You should force an app to close only when it’s unresponsive.
Update: MacDailyNews quotes a 2010 email from Steve Jobs:
Just use [iOS multitasking] as designed, and you’ll be happy. No need to ever quit apps.
Just in case you don’t believe Apple’s senior vice president for software, Apple’s own official support documentation, or Steve Jobs, here are some other articles pointing out how this habit is actually detrimental to iPhone battery life:
This thing about force quitting apps in the background is such a pernicious myth that I’ve heard numerous stories from DF readers about Apple Store Genius Bar staff recommending it to customers. Those “geniuses” are anything but geniuses.
It occurs to me that some of the best examples proving that this notion is wrong (at least in terms of performance) are YouTube “speed test” benchmarks. There’s an entire genre of YouTube videos devoted to benchmarking new phones by running them through a series of apps and CPU-intensive tasks repeatedly, going through the loop twice. Once from a cold boot and the second time immediately after the first loop. Here’s a perfect example, pitting a Samsung Galaxy S8 against an iPhone 7 Plus. Note that no apps are manually force quit on either device. The iPhone easily wins on the first loop, but where the iPhone really shines is on the second loop. The S8 has to relaunch all (or at least almost all) of the apps, because Android has forced them to quit while in the background to reclaim the RAM they were using. On the iPhone, all (or nearly all) of the apps re-animate almost instantly.
In fact, apps frozen in the background on iOS unfreeze so quickly that I think it actually helps perpetuate the myth that you should force quit them: if you’re worried that background apps are draining your battery and you see how quickly they load from the background, it’s a reasonable assumption to believe that they never stopped running. But they did. They really do get frozen, the RAM they were using really does get reclaimed by the system, and they really do unfreeze and come back to life that quickly.1
An awful lot of very hard work went into making iOS work like this. It’s a huge technical advantage that iOS holds over Android. And every iPhone user in the world who habitually force quits background apps manually is wasting all of the effort that went into this while simultaneously wasting their own device’s battery life and making everything slower for themselves.
This pernicious myth is longstanding and seemingly will not die. I wrote about it at length back in 2012:
Like with any voodoo, there are die-hard believers. I’m quite certain that I am going to receive email from people who will swear up-and-down that emptying this list of used applications every hour or so keeps their iPhone running better than it would otherwise. Nonsense.
As Fraser mentions, yes, there are exceptional situations where an app with background privileges can get stuck, and you need to kill that app. The argument here is not that you should never have to kill any app using the multitasking switcher — the argument is that you don’t need to do it on a regular basis, and you’re not making anything “better” by clearing the list. Shame on the “geniuses” who are peddling this advice.
And don’t even get me started on people who completely power down their iPhones while putting them back into their pockets or purses. ★
The other contributing factor to believing that force quitting is good for your iPhone are the handful of apps that have been found to be repeated abusers of loopholes in iOS, such that they really do continue running in the background, wasting battery life. Most infamously, Facebook was caught playing silent audio tracks in the background to take advantage of APIs that allow audio-playing apps to play audio from the background. They called it a “bug”. In those cases force-quitting the apps really did help, and I see no reason to trust Facebook. So if you want to keep force quitting Facebook, go right ahead. But don’t let one bad app spoil the whole barrel. The Battery section in the iOS Settings app can show you which apps are actually consuming energy in the background — tap the clock icon under “Battery Usage” and don’t force quit any app that isn’t a genuine culprit. ↩︎
Rene Ritchie, “iPhones of Future Past: Understanding iPhone 8”:
iPhone 8 will simply let Apple impress in a different way — by including technologies that don’t yet reach iPhone scale. In other words, by bringing tomorrow’s iPhone to market today.
In terms of the business, it’s really no different than getting an iPhone onto Verizon, onto China Mobile, with bigger and bigger displays, or with smaller displays again — it’s about annexing adjacent markets and maximizing the revenue potential for iPhone.
As it becomes harder to sell more iPhones — the population of earth is now a limiting factor — selling more of an iPhone becomes beneficial. It’s the same benefit Apple gets from selling services revenue on top of iPhone, but in atoms, not bits.
Ritchie is using the name “iPhone 8” to refer to what I’ve called the “iPhone Pro” — the high-end OLED-display model that I think might start at over $1000. Name aside, I think he’s got exactly the right idea on how Apple can position this: a future iPhone today.
Honda used to sell a car in the U.S. called the Prelude. Edmunds’s description:
Honda established itself in America with the Civic and Accord — both good, solid but basic cars. But big profits in the automotive world don’t come from basic cars that sell for commodity prices. Those profits come from cars that get consumers so excited that they’ll pay a premium price just to have one. The Prelude was Honda’s first attempt at an exciting car.
The Prelude was Honda’s technological leading edge. Features that are now expected from Honda, like the double-wishbone suspension under the Accord, fuel injection, and VTEC electronic variable valve timing system showed up first on the Prelude before migrating across the Honda line (though VTEC first showed up on the 1990 Acura NSX). The Prelude was also a test bed for some technologies that went nowhere, like four-wheel steering.
In a broad sense, that’s my idea for the iPhone Pro — a premium-priced product that offers us early access to technologies and components that will be (or even just might be) in all iPhones in another year or two. ★
Yours truly, in a tweet on July 7:
I’ve heard that inductive charging will (a) be sold separately, and (b) might be late, waiting for iOS 11.1 (a la Portrait mode last year). https://twitter.com/ATP_Tipster1/status/883457889729425408
On July 11, Mark Sullivan reported a piece for Fast Company under the headline “Source: A ‘Sense of Panic’ at Apple as the Next Flagship iPhone’s Software Problems Persist”:
June was a tense month for the engineers and designers on Apple’s iPhone team with “a sense of panic in the air,” a source with knowledge of the situation tells me.
The company has been working feverishly to fix software problems in its hotly anticipated 10th-anniversary iPhone that could ultimately cause production and delivery delays, the source says. If the software problems aren’t resolved quickly, the new flagship iPhone could even launch with major features disabled. […]
One of those is wireless charging. The iPhone 8 — let’s call it that for now — will reportedly use a type of inductive charging, where the phone sits directly on a separate charging device. (Our source believes Apple is using the Qi wireless charging standard, or a variant of it.) The wireless charging components, which are provided by chipmaker Broadcom Ltd., are not the key issue, the source said; it’s the software that’s not ready for prime time.
That sort of matches up with what I heard — that inductive charging might miss the September debut because the software isn’t ready. I have not heard anything about any sort of “panic”. Summers are crunch time for iOS engineers, and the deadline for iOS 11.0 is probably no more than a month away at this point. But if inductive charging has to wait until 11.1 in October or November, it’ll be a disappointment, but not much more so than having to wait for the iPhone 7 Plus’s Portrait Mode to come out of beta last fall.
It’s the same thing every year these days. It’s incredibly predictable.
It goes like this: Having reported every claimed product feature people then switch to criticizing all those features, and — when the shelf life on “anti-reports” of this kind time out, the self-same sources swiftly shift to shuffling speculation saying such-and-such features will apparently be “delayed”. Seriously!
All of this drama and Apple hasn’t even announced anything yet.
How can something that hasn’t been announced ever be delayed?
“Apple engineers are panicking” is an exciting story. “Apple engineers are in crunch mode to finish iOS 11.0 just like they are every summer” is not.
It could be that things are in worse shape than usual, and there truly is a panic to get iOS 11’s support for new iPhone hardware finished on schedule. But everything I’ve heard suggests it’s the same as usual at this point in the summer: busy down to the wire, yes; frantic panic, no.
Today Sullivan has another report, claiming Apple is trying to integrate laser sensors into the rear of the high-end new iPhone:
A source with knowledge of the situation tells Fast Company Apple is working hard to add a rear-facing 3D laser system to the back of one of the new iPhones to be announced this fall. […]
The source said the VSCEL laser system is probably intended for the 10th anniversary iPhone (which may be called the iPhone 8 or the iPhone Pro or, hopefully, the iPhone X). Whether the sensor will be included in that phone, or a 2018 iPhone, depends on the progress the Apple engineers make in integrating the laser system into the phone, our source says.
This sounds cool — and also sounds like the sort of feature that could justify a significantly higher price for an iPhone Pro.
But I think it’s bonkers to think that Apple is still working on hardware decisions like this in the middle of July. Apple is super-secretive about this stuff, but from what I’ve gathered over the years, by this state in the game the hardware design has long been decided. They’re in the late stages of validation testing, not designing.
For a volume Sep. launch, production tooling is being ground right now. It’s been pencils down for a while.
If not? Huge shit show.
With software Apple can (and does) play a bit fast and loose. iOS 11.0 won’t be baked until late August. But software can (and always is) patched. Hardware doesn’t work like that. Many of the decisions related to the hardware on this year’s new iPhones were made two years ago. (And there are decisions being made now for 2019’s new iPhones.)
Is there a 3D laser sensor on the back of the new iPhone? Is there a Touch ID sensor?1 I don’t know. But Apple knows, and has known for a while. Months, even.
If the hardware were still up in the air today, it’d be an impossible target for the software, never mind for Apple’s incredibly high-scale production ramp. I believe Apple is months ahead of these rumors — what we hear now with reports like this are just echoes of decisions that have already been made. ★
Might as well address this rumor here. A ton of readers have expressed deep skepticism regarding reports that the OLED iPhone doesn’t have a Touch ID sensor. “That’s impossible, Apple Pay relies on Touch ID” is the basic sentiment. I think it’s possible that there’s no Touch ID sensor on the OLED iPhone, but if that’s the case, then the new 3D face scanner has to be as good or better than Touch ID in every regard. It has to be just as fast, just as accurate, and just as trustworthy. It also would have to work from a wide range of angles. As Rene Ritchie has sagely written, the end game is “persistent, ambient authentication” — fingerprints are not particularly magic.
But, if the new iPhone ships without a Touch ID sensor and there is no replacement authentication technology that is as good or better than Touch ID — that would be a dead canary in the coal mine. ↩︎