I find this to be untrue. Too many apps are actively reaching out to the internet when left to their own devices, causing unnecessary battery drain. I have had to resort to closing my apps just to get decent battery life.
How do I know this outside of battery drain you might ask? Ever had your phone get ridiculously warm in your pocket for no reason? Next time that happens, close your apps and see if it cools down.
Closing the apps help not save the battery but free up allocated memory that every app in the background uses. Have enough them open and phone available memory gets really low. Had memory apps that showed memory usage and it proved that it was the case.
Nope.
Could you elaborate more than the "Nope" Statement? Are you saying that the apps in the background mode do not use memory allocation?
Old habits are hard to break. Ingrained beliefs are hard to let go of. I put this the on the "clean install" and "hard disk optimization" wives tales list. To this day a lot of techie wannabes will buy a new Mac, take it out of the box, reformat the hard drive and perform what they call a "clean install" to ensure purity and chastity in their device. Then there those who still waste time "optimizing" their hard drives secure in the wive's tale that their system will access files faster. They even enquire as to a utility to 'optimize' a SSD when SSDs handle files totally differently from a spinning drive. The bottom line is that these techniques don't really work but they don't really cause any trouble either so why chastise those of us who still insist on using them.
I find this to be untrue. Too many apps are actively reaching out to the internet when left to their own devices, causing unnecessary battery drain. I have had to resort to closing my apps just to get decent battery life.
How do I know this outside of battery drain you might ask? Ever had your phone get ridiculously warm in your pocket for no reason? Next time that happens, close your apps and see if it cools down.
Closing the apps help not save the battery but free up allocated memory that every app in the background uses. Have enough them open and phone available memory gets really low. Had memory apps that showed memory usage and it proved that it was the case.
Nope.
Could you elaborate more than the "Nope" Statement? Are you saying that the apps in the background mode do not use memory allocation?
That's exactly what Apple says and they should know.
I agree with some prior comments, what is said in this video is untrue. Many apps run background processes which are killed off if you manually remove them from the active list (although some like Facebook run no matter what you).
Can you please provide some examples of background processes that apps run? Audio can be one, but that one's pretty obvious. What other processes are my apps running in the background and how long do those processes run? Thanks!
Sure thing! An app is allowed to run in the background (for non-trivial amounts of time) for the following types of tasks:
1. Audio, AirPlay, and Picture-in-Picture 2. Location updates (eg, mapping) but only if it asks for location updates "always" instead of "when in use". (By the way, "always" actually means when the app has been launched and is still running in the background; if you force-close the app, then it no longer gets location updates. I think they should reword "always" to mean "if in foreground or background" and reword "when in use" to mean "only when in the foreground".) 3. Voice over IP 4. Newsstand downloads 5. External accessory communication 6. Uses Bluetooth LE accessories 7. Acts as a Bluetooth LE accessory 8. Background fetch (the app will be "woken up" every now and then so it can download any info it needs from the Internet) 9. Remote notifications (a remote / "push" notification can be sent that will let the app run for a short time in the background)
Note that these aren't simply loopholes; the apps have to actually use that feature. For example, if an app provides voice over IP, it can run in the background when handling a call. But when the call ends, the app goes to sleep again. (It gets woken up by iOS when a new call comes in.)
In addition, all apps run for a very short time (up to ~10 seconds) when they are put into the background, so that they can save their state / data. If they need extra time (eg, to finish a large download), they can request a little more time; in iOS 10 this tends to be around 179 seconds in my testing. But they have to actually do something during that time, and can't simply go into a loop requesting another 179 seconds.
To flesh out a related topic: when you put an app into the background, it has a short time (~10 seconds) to save its "state." As stated in answer #25, when you bring it back into the foreground, it will restore its state, so it looks to you like it is still running, even though it may have been completely removed from memory if iOS needed to do so. (But you have no way of knowing if this happened, and you really don't care.) A caveat is that if you manually force-close an app, then the last saved state information is deleted, so the next time you launch the app it will launch from a "clean" state. This may be useful sometimes if the app has subtle bugs in its state saving / restoration code.
1) Those who've gone/watched WWDC sessions, read Apple's documentation, develop apps themselves, have worked on iOS, etc... and are re-enforcing the points made in the video.
2) Those who haven't, but "believe" the video is wrong for some reason they can't adequately explain.
I agree with some prior comments, what is said in this video is untrue. Many apps run background processes which are killed off if you manually remove them from the active list (although some like Facebook run no matter what you).
Can you please provide some examples of background processes that apps run? Audio can be one, but that one's pretty obvious. What other processes are my apps running in the background and how long do those processes run? Thanks!
Sure thing! An app is allowed to run in the background (for non-trivial amounts of time) for the following types of tasks:
1. Audio, AirPlay, and Picture-in-Picture 2. Location updates (eg, mapping) but only if it asks for location updates "always" instead of "when in use". (By the way, "always" actually means when the app has been launched and is still running in the background; if you force-close the app, then it no longer gets location updates. I think they should reword "always" to mean "if in foreground or background" and reword "when in use" to mean "only when in the foreground".) 3. Voice over IP 4. Newsstand downloads 5. External accessory communication 6. Uses Bluetooth LE accessories 7. Acts as a Bluetooth LE accessory 8. Background fetch (the app will be "woken up" every now and then so it can download any info it needs from the Internet) 9. Remote notifications (a remote / "push" notification can be sent that will let the app run for a short time in the background)
Note that these aren't simply loopholes; the apps have to actually use that feature. For example, if an app provides voice over IP, it can run in the background when handling a call. But when the call ends, the app goes to sleep again. (It gets woken up by iOS when a new call comes in.)
In addition, all apps run for a very short time (up to ~10 seconds) when they are put into the background, so that they can save their state / data. If they need extra time (eg, to finish a large download), they can request a little more time; in iOS 10 this tends to be around 179 seconds in my testing. But they have to actually do something during that time, and can't simply go into a loop requesting another 179 seconds.
To flesh out a related topic: when you put an app into the background, it has a short time (~10 seconds) to save its "state." As stated in answer #25, when you bring it back into the foreground, it will restore its state, so it looks to you like it is still running, even though it may have been completely removed from memory if iOS needed to do so. (But you have no way of knowing if this happened, and you really don't care.) A caveat is that if you manually force-close an app, then the last saved state information is deleted, so the next time you launch the app it will launch from a "clean" state. This may be useful sometimes if the app has subtle bugs in its state saving / restoration code.
Perfect! Your post seems to be supporting that compulsively force quitting apps is unnecessary. A notion that is fully supported by Apple. TBH, I was hoping to get the response from the person I was responding to who seems to believe that force quitting their apps is required and a good thing overall.
The examples you provided for background app processes, in general, are not quietly using resources and slowly draining the phone's battery while the user remains unaware. I can't really imagine a scenario where a person is, say, using their Bluetooth headset while making a VoIP call and using Safari while the VoIP app is in the background would be surprised to find that their battery is draining faster than it would while their phone is asleep in their pocket. But some people will force quit their VoIP app and Safari before putting the phone to sleep and stowing it believing that not doing so is draining their battery. Again, I feel like your post is in support of not needing to force quit all your apps all the time, of which I agree.
The following happens to me on a weekly basis: all of a sudden Safari won't load a webpage - it will just sit there teasing me with its tiny blue progress line. So I close a bunch of apps and when I return to Safari the page loads lickety-split. I have a ton of tabs open, which may or may not also cause a problem. But hey, the 'experts' keep telling me it's pointless to close apps, so my experience must be bs right?!
When did this story pop up again? I've been seeing it everywhere. This issue was current, relevant and settled 5+ years go. You don't have to bother unless it's a problematic app. Duh
* edit: should have read Krups post above. What a stupid reason to revive this debate.
I find this to be untrue. Too many apps are actively reaching out to the internet when left to their own devices, causing unnecessary battery drain. I have had to resort to closing my apps just to get decent battery life.
How do I know this outside of battery drain you might ask? Ever had your phone get ridiculously warm in your pocket for no reason? Next time that happens, close your apps and see if it cools down.
Closing the apps help not save the battery but free up allocated memory that every app in the background uses. Have enough them open and phone available memory gets really low. Had memory apps that showed memory usage and it proved that it was the case.
Nope.
Could you elaborate more than the "Nope" Statement? Are you saying that the apps in the background mode do not use memory allocation?
For starters, you can stop referring to it as "background mode." As its been stated over and over again in this fucking thread, the apps listed in Fast App Switcher are merely a reverse order of usage. They may or may not be currently running and they may or may not have been purged from RAM. There's literally no way to tell by looking at the list of recently used apps in FAS.
Again, the fucking list of apps in FAS has nothing to do with what is currently taking up address space in RAM, using CPU cycles, or connecting to a network or other components on the device. It's just a handy way to switch between apps most recently used.
If people really can't understand this simple concept that is far from being a *new* feature, then maybe Apple should just remove this convenience, secondary feature of FAS that may or may not stop an app from utilizing the network or other components, stop its use of the CPU, and remove it from RAM.
I disagree. Obviously, at least some memory is being taken up when apps are left open. Even if it's just a screenshot of the app being cached, it's still taking up some memory. But the fact of the matter is, it's not just a screenshot of the app being cached. The app actually is opened and is therefore taking up memory of some kind... obviously. I believe the video demonstrates, in theory, that you SHOULD close your apps on your iPhone/iPad: He says the only reason you should close an app is if it crashes. But if the app crashes while it's opened then is that not evidence that the app is opened and running in the background? And if it's running in the background, is it not using memory? If it's using memory does that not potentially impact performance at some level, even if perhaps minuscule? And thus, the more apps you have opened the greater the impact of that potential performance decrease? Okay, perhaps opened apps are in some dedicated memory for background tasks... but in the end it's still sitting in memory and memory has a limit. So I think it's only common sense and reasonable to quit apps from time to time. I don't think one has to be obsessive about it, but being conscious of it is absolutely wise and to one's advantage. I think this video/article telling folks to NOT force close apps because it's a "waste of time" is... unfortunate.
So despite the fact that this is the way iOS is designed, despite what Apple executives state and what is reinforced by Apple documentation you disagree because of what you, personally, believe? THAT is unfortunate.
What is unfortunate is buying Apple line hook, line and sinker. It has been demonstrated again and again that not all appps play by the rules or work in the users best interest. At that point the best thing you can do is to exit those apps to get the system working correctly. This isnt compulsive exiting but rather smart exiting.
Ask yourself this, if you just closed all apps and the system returned to normal operation, is the practice good or bad? Further if you identify an app that consistently causes you problems does it not make sense to compulsively close that app? Unfortunaty to many want to bury their hears in the sand hereand believe one practice is good 100% of the time.
Yup, you're right. Not all apps have played by the rules (Facebook) and need to be force quit. That falls under the "misbehaving" category that is mentioned in the video when Max says "unresponsive or erratic behavior". As you said, the best thing you can do is exit those apps. But that isn't what this topic is about, it's about people who force quit all of their apps (not just misbehaving app, all apps) multiple times a day in the belief that doing so is increasing their battery life, which is false.
You ask if the practice of closing all apps is good or bad. It's bad if you're doing it all the time to all apps hoping to increase battery life. Why? Because it takes the app out of it's suspended state and the next time you launch it it has to start fresh, which generally will take longer and thus decrease battery life.
I have papers all over my real life desktop. I clean up the papers, even though it doesn't make "sense" because I'll probably just have to get them out of the filing cabinet again. Why do I do this? Because I hate having a messy desktop! And I don't like having a messy phone with lots of open apps that I know I won't need that day.
What's Apple's solution? NEVER close an app? So eventually, you will have ALL of your apps open at the same time, assuming that you actually use them! Then what? You have to scroll through every single app on your phone to shift from using one to another one?
No. Close the apps. Keep it streamlined and tidy. Sorry, Apple. You're going against intuition here.
I have papers all over my real life desktop. I clean up the papers, even though it doesn't make "sense" because I'll probably just have to get them out of the filing cabinet again. Why do I do this? Because I hate having a messy desktop! And I don't like having a messy phone with lots of open apps that I know I won't need that day.
What's Apple's solution? NEVER close an app? So eventually, you will have ALL of your apps open at the same time, assuming that you actually use them! Then what? You have to scroll through every single app on your phone to shift from using one to another one?
Your analogy is off. The FAS is more like your filing cabinet, not the desktop. This is like saying it makes more sense to throw away all the papers in your filing cabinet every day because you can reprint them the next day. You don't really have a "messy phone with lots of open apps", you have an app switcher with apps that are not open.
And Apple's solution isn't to NEVER close apps, especially since they provide a way to close apps. That's just an odd comment. FWIW, pretty much every app I have is in my FAS. I can scroll through it until I get to the Tips app which I haven't looked at since the day I picked up my iPhone 7 in November. And, of course I don't have to scroll through every single app on my phone to shift form using one to another one. There are several different ways to open apps including tapping on their icon on the home screen or dock and searching for them or asking Siri to open them.
There appear to be two (ok 3) concerns raised by the "pro-quit" camp. 1. These apps are "doing something" that is taking up CPU cycles and eating into my battery life. 2. These apps are "wasting" memory. (3. They clutter up the list of apps when I go to the app switcher). My understanding is that 1. is possibly true and a good reason to kill certain apps but 2. is a waste of time.
The memory model for iOS is as follows: apps get as much memory as they need/request so long as they are the active (front) app. Background apps can keep their memory until the system needs memory for the front app (or system stuff). When memory is needed, the system sends a message to all apps telling them to free up as much memory as possible. Well-behaved apps will respond to that message by clearing cache memory and otherwise reducing its memory footprint. This happens nearly instantaneously. Either this frees up enough memory to allow the front app to proceed or it doesn't. If it doesn't the system then--in a vary draconian fashion--starts telling background apps to shut down (and they do).
So when you bring a background app to the front, one of three things happen from a memory perspective. In the "best" case, the app never had to give up any memory, so it's ready to go. Alternatively, it's given up some memory so some cached resources have to be restored (from disk or the network). Or, the app had been killed and it needs to boot up from scratch. The user is not told which of these occurs (much might be able to tell based on duration or progress bars). Therefore users had the impression that background apps are always using up memory, when in fact they are only allowed to keep memory if other foreground applications didn't need it. Therefore manually killing background apps just to free up memory is completely pointless. iOS does that automatically.
There are a range of devices with different specs. When I had early iOS devices with 256MB of memory, the memory didn't free up smoothly. I had games crash with out of memory errors in the log files and I could only keep them stable by manually quitting Safari and other background apps. If heavy memory apps were open in the background, the foreground apps just crashed. On devices with more memory, this is not as likely to happen. Even the iPhone SE has 2GB of memory now and the OS uses memory compression so crashes due to memory issues are pretty much never going to happen but it can be a force of habit for people coming from older devices where it did make a difference (iPhone 4S and below with maximum 512MB memory). Some people still use those older devices and clearing out the memory with a device reboot as decribed in the following article improves performance:
Location apps drain the battery more quickly in the background. Having a map open in the background with the GPS active drains more quickly than with GPS deselected. The following site lists a few social media apps that drain battery in the background:
You could disable background refresh but quitting the app is quicker than digging through the menus. On wifi, background refresh isn't so bad but on cellular, it uses more power, especially in low signal areas so it's easier to just swipe the apps away when outside than toggling the refresh on/off based on where you are.
It's not just a placebo effect, people can see the benefits to quitting some apps right after closing them so it's perfectly ok for people to quit apps when they know that certain apps drain too much battery in the background. Decluttering the app switcher is a valid reason too.
I really doubt that quitting apps is offsetting battery gains from suspending background activity to the point that people should be encouraged not to do it. Even if people quit every app once an hour, it's not going to negatively impact battery life. It would be best to run through a real-world test and measure the battery life using the phone each way to see the difference. I would expect to see the biggest difference coming from suspending background activity, especially on cellular and negligible difference whether this is achieved via quitting the apps or suspending background refresh.
I find this to be untrue. Too many apps are actively reaching out to the internet when left to their own devices, causing unnecessary battery drain. I have had to resort to closing my apps just to get decent battery life.
How do I know this outside of battery drain you might ask? Ever had your phone get ridiculously warm in your pocket for no reason? Next time that happens, close your apps and see if it cools down.
Closing the apps help not save the battery but free up allocated memory that every app in the background uses. Have enough them open and phone available memory gets really low. Had memory apps that showed memory usage and it proved that it was the case.
Nope.
Could you elaborate more than the "Nope" statement?
I find this to be untrue. Too many apps are actively reaching out to the internet when left to their own devices, causing unnecessary battery drain. I have had to resort to closing my apps just to get decent battery life.
How do I know this outside of battery drain you might ask? Ever had your phone get ridiculously warm in your pocket for no reason? Next time that happens, close your apps and see if it cools down.
Closing the apps help not save the battery but free up allocated memory that every app in the background uses. Have enough them open and phone available memory gets really low. Had memory apps that showed memory usage and it proved that it was the case.
Nope.
Could you elaborate more than the "Nope" statement?
I find this to be untrue. Too many apps are actively reaching out to the internet when left to their own devices, causing unnecessary battery drain. I have had to resort to closing my apps just to get decent battery life.
How do I know this outside of battery drain you might ask? Ever had your phone get ridiculously warm in your pocket for no reason? Next time that happens, close your apps and see if it cools down.
Closing the apps help not save the battery but free up allocated memory that every app in the background uses. Have enough them open and phone available memory gets really low. Had memory apps that showed memory usage and it proved that it was the case.
Nope.
Could you elaborate more than the "Nope" Statement? Are you saying that the apps in the background mode do not use memory allocation?
For starters, you can stop referring to it as "background mode." As its been stated over and over again in this fucking thread, the apps listed in Fast App Switcher are merely a reverse order of usage. They may or may not be currently running and they may or may not have been purged from RAM. There's literally no way to tell by looking at the list of recently used apps in FAS.
Again, the fucking list of apps in FAS has nothing to do with what is currently taking up address space in RAM, using CPU cycles, or connecting to a network or other components on the device. It's just a handy way to switch between apps most recently used.
If people really can't understand this simple concept that is far from being a *new* feature, then maybe Apple should just remove this convenience, secondary feature of FAS that may or may not stop an app from utilizing the network or other components, stop its use of the CPU, and remove it from RAM.
The fact is there are more misbehaving apps than folks assume.
As a dev I force close apps fairly often in order to dump some apps that I do want to set to work in the background but not anymore. That does free up resources and no, I don't want to set them to not work in background. When I'm using them I want to switch back and forth quickly but I don't want them up all the time because they are a battery suck.
Try running Maps, Google Maps, Waze, TomTom and NAVAGON all in Turn-by-turn navigation mode, as well as Find my Friend and Find my iPhone apps tracking s friend and s device, and you'll know why you should close them all. Other location tracking apps behave similarly.
Craig Federighi doesn't want you to close the apps, of course, otherwise, how can Apple and the apps collect your data?
Conclusion: Close as many apps as you have the spare time.
Having Ng said that, I'm using iOS 10, not sure yet about iOS 11.
People who compulsively force close all apps on their iPhone in a futile effort to conserve battery life are wasting their time. AppleInsider explains why you should ditch this pointless habit.
This may be true for well-written apps, but not all apps are well-written - even popular ones.
I seem to recall the Facebook app causing short battery life even when it wasn't "active" a while back.
Turn off Background App Refresh for Facebook.
The problem is people think force quitting everything is the solution, when really the solution is to understand where to look for battery usage stats by app and adjust their settings accordingly.
People who compulsively force close all apps on their iPhone in a futile effort to conserve battery life are wasting their time. AppleInsider explains why you should ditch this pointless habit.
This may be true for well-written apps, but not all apps are well-written - even popular ones.
I seem to recall the Facebook app causing short battery life even when it wasn't "active" a while back.
Turn off Background App Refresh for Facebook.
The problem is people think force quitting everything is the solution, when really the solution is to understand where to look for battery usage stats by app and adjust their settings accordingly.
You tell people that and they don't listen. Instead of being reasonable and taking logical steps to figure out what could be causing an unnecessary drain they invent BS to support their irrational behaviour.
People who compulsively force close all apps on their iPhone in a futile effort to conserve battery life are wasting their time. AppleInsider explains why you should ditch this pointless habit.
This may be true for well-written apps, but not all apps are well-written - even popular ones.
I seem to recall the Facebook app causing short battery life even when it wasn't "active" a while back.
Turn off Background App Refresh for Facebook.
The problem is people think force quitting everything is the solution, when really the solution is to understand where to look for battery usage stats by app and adjust their settings accordingly.
You tell people that and they don't listen. Instead of being reasonable and taking logical steps to figure out what could be causing an unnecessary drain they invent BS to support their irrational behaviour.
Oh, I know. I posted Gruber's article about this on Facebook and got quite a bit of backlash, mostly incredulity that "everyone" could've had it wrong for so long, or "Apple people tell you Apple things work as advertised, film at 11" type cynicism.
You can lead a horse to water, but you can't make it drink.
Comments
1. Audio, AirPlay, and Picture-in-Picture
2. Location updates (eg, mapping) but only if it asks for location updates "always" instead of "when in use". (By the way, "always" actually means when the app has been launched and is still running in the background; if you force-close the app, then it no longer gets location updates. I think they should reword "always" to mean "if in foreground or background" and reword "when in use" to mean "only when in the foreground".)
3. Voice over IP
4. Newsstand downloads
5. External accessory communication
6. Uses Bluetooth LE accessories
7. Acts as a Bluetooth LE accessory
8. Background fetch (the app will be "woken up" every now and then so it can download any info it needs from the Internet)
9. Remote notifications (a remote / "push" notification can be sent that will let the app run for a short time in the background)
Note that these aren't simply loopholes; the apps have to actually use that feature. For example, if an app provides voice over IP, it can run in the background when handling a call. But when the call ends, the app goes to sleep again. (It gets woken up by iOS when a new call comes in.)
In addition, all apps run for a very short time (up to ~10 seconds) when they are put into the background, so that they can save their state / data. If they need extra time (eg, to finish a large download), they can request a little more time; in iOS 10 this tends to be around 179 seconds in my testing. But they have to actually do something during that time, and can't simply go into a loop requesting another 179 seconds.
Beyond that, answers #25 (by Xmcgraw) and #31 (by Randominternetperson) have a good overview of memory management.
To flesh out a related topic: when you put an app into the background, it has a short time (~10 seconds) to save its "state." As stated in answer #25, when you bring it back into the foreground, it will restore its state, so it looks to you like it is still running, even though it may have been completely removed from memory if iOS needed to do so. (But you have no way of knowing if this happened, and you really don't care.) A caveat is that if you manually force-close an app, then the last saved state information is deleted, so the next time you launch the app it will launch from a "clean" state. This may be useful sometimes if the app has subtle bugs in its state saving / restoration code.
1) Those who've gone/watched WWDC sessions, read Apple's documentation, develop apps themselves, have worked on iOS, etc... and are re-enforcing the points made in the video.
2) Those who haven't, but "believe" the video is wrong for some reason they can't adequately explain.
Choose wisely upon where take your advice.
The examples you provided for background app processes, in general, are not quietly using resources and slowly draining the phone's battery while the user remains unaware. I can't really imagine a scenario where a person is, say, using their Bluetooth headset while making a VoIP call and using Safari while the VoIP app is in the background would be surprised to find that their battery is draining faster than it would while their phone is asleep in their pocket. But some people will force quit their VoIP app and Safari before putting the phone to sleep and stowing it believing that not doing so is draining their battery. Again, I feel like your post is in support of not needing to force quit all your apps all the time, of which I agree.
* edit: should have read Krups post above. What a stupid reason to revive this debate.
Again, the fucking list of apps in FAS has nothing to do with what is currently taking up address space in RAM, using CPU cycles, or connecting to a network or other components on the device. It's just a handy way to switch between apps most recently used.
If people really can't understand this simple concept that is far from being a *new* feature, then maybe Apple should just remove this convenience, secondary feature of FAS that may or may not stop an app from utilizing the network or other components, stop its use of the CPU, and remove it from RAM.
You ask if the practice of closing all apps is good or bad. It's bad if you're doing it all the time to all apps hoping to increase battery life. Why? Because it takes the app out of it's suspended state and the next time you launch it it has to start fresh, which generally will take longer and thus decrease battery life.
What's Apple's solution? NEVER close an app? So eventually, you will have ALL of your apps open at the same time, assuming that you actually use them! Then what? You have to scroll through every single app on your phone to shift from using one to another one?
No. Close the apps. Keep it streamlined and tidy. Sorry, Apple. You're going against intuition here.
And Apple's solution isn't to NEVER close apps, especially since they provide a way to close apps. That's just an odd comment. FWIW, pretty much every app I have is in my FAS. I can scroll through it until I get to the Tips app which I haven't looked at since the day I picked up my iPhone 7 in November. And, of course I don't have to scroll through every single app on my phone to shift form using one to another one. There are several different ways to open apps including tapping on their icon on the home screen or dock and searching for them or asking Siri to open them.
http://www.independent.co.uk/life-style/gadgets-and-tech/news/it-only-takes-10-seconds-to-reset-your-iphone-ram-and-make-it-run-quicker-heres-how-a6765206.html
Location apps drain the battery more quickly in the background. Having a map open in the background with the GPS active drains more quickly than with GPS deselected. The following site lists a few social media apps that drain battery in the background:
http://www.idownloadblog.com/2016/03/22/top-five-iphone-battery-hogs/
You could disable background refresh but quitting the app is quicker than digging through the menus. On wifi, background refresh isn't so bad but on cellular, it uses more power, especially in low signal areas so it's easier to just swipe the apps away when outside than toggling the refresh on/off based on where you are.
It's not just a placebo effect, people can see the benefits to quitting some apps right after closing them so it's perfectly ok for people to quit apps when they know that certain apps drain too much battery in the background. Decluttering the app switcher is a valid reason too.
I really doubt that quitting apps is offsetting battery gains from suspending background activity to the point that people should be encouraged not to do it. Even if people quit every app once an hour, it's not going to negatively impact battery life. It would be best to run through a real-world test and measure the battery life using the phone each way to see the difference. I would expect to see the biggest difference coming from suspending background activity, especially on cellular and negligible difference whether this is achieved via quitting the apps or suspending background refresh.
As a dev I force close apps fairly often in order to dump some apps that I do want to set to work in the background but not anymore. That does free up resources and no, I don't want to set them to not work in background. When I'm using them I want to switch back and forth quickly but I don't want them up all the time because they are a battery suck.
Craig Federighi doesn't want you to close the apps, of course, otherwise, how can Apple and the apps collect your data?
Conclusion: Close as many apps as you have the spare time.
Having Ng said that, I'm using iOS 10, not sure yet about iOS 11.
The problem is people think force quitting everything is the solution, when really the solution is to understand where to look for battery usage stats by app and adjust their settings accordingly.
You can lead a horse to water, but you can't make it drink.