Developer Clears Misconceptions About iOS Multitasking
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Developer Clears Misconceptions About iOS Multitasking
Fraser Speirs developer at Connected Flow and Head of Computing and IT at Cedars School of Excellence has written an excellent article to clear the misconceptions about iOS multitasking.
Comments
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Thanks for the info. Good to know.
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From a developer standpoint, all of the above may very well be sufficient as far as coding your application goes. For most iOS users, it should be transparent and "just work". However, I think a site like this caters to those of us who want our iOS devices to "just work BETTER".Manually closing apps in the multitask bar significantly improves performance, if not battery life. My devices (especially my first gen iPad) start getting very sluggish after running a few apps - and occasionally crash when launching RAM-intensive apps. I don't notice as much on my 4S, but I'm sure it is also affected. Manually closing apps in the bar (or using tweaks) and freeing memory brings it back to speed.While I'm using a mobile device, I have very little patience for waiting for iOS to decide which apps to transition from "suspended" to "not running" when I've pulled my hands out of their warm gloves. I want it to work instantly, not after iOS has leisurely decided which apps it deems no longer worthy of RAM allocation.A better way to summerize the article may be that while you may not NEED to close backgrounded apps, you very well may WANT to.
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Excellent article, real good info. to know. Question? If by hitting the home button the running app. quits, then the recent tweak Zephyr by Chpwn is a fail?Thank you Iphonehacks for all the latest news!
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The main question is - how to determine how is a particular app behaving.You can run an easiest test: on a device with SBS check available memory and wright it down Run a program (a game, let's say) that does not use GPS, 3g, WiFi or anything else. Go to home screen, run another similar app or 2. Check your memory - it will go down (usually significantly, depending on the size of the app). So most of the apps are Suspended. It is my understanding that if the app is in the memory - the CPU has to work with allocating and re-allocating the memory, the suspended apps do consume battery. Would love to be wring though =)
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i have a question...if the apps are not running then what is the use of the close button that appears on the apps when u press and hold an app ?? o.O
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Sorry. A quick search of forums relating to battery issues on the iPhone will show significant stats that indicate this article has some holes. This is the second article like this I've read in a week and both tell a story of a perfect world where everything the hardware and software does exactly as its supposed too. Nope. Apples implementation of "task Switching" isn't as eloquent as is stated. And even then nobody's going to keep track of which apps are going to be using background resources, etc to know which ones to close. I'll stick with my jailbreak and "remove background" tweak thanks. As well as "automatic location". Apples all or nothing philosophy on functionality needs to back te truck up and steal some more good ideas from the jailbreak community. IMHO.
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Ok, so I'm at the Genious Bar about a year ago with my iPhone whose battery suddenly, overnight, started dying in a few hours of standby time, and they start closing Apps from the Multitasking Bar and inform me that was my problem. I told them, no, there's a real problem here, those Apps are not using power, and they said, I'm not making this up, "How do you think they exist if they're not using energy?" Then, they stood there with a bunch of other customers they had been chatting with, holds their Starbucks cups, literally laughing at, pointing, and overtly mocking me. I told them Steve pulls that attitude off because he is successful, and gave them the old line about their goofy opinions qualifying them for a refund of their tuition, then went to the manager who offered to replace my iPhone. I don't think he believed it was broke, he just realized his staff let a bit too much of their true opinions known.But no, I was suspicious. Why had the phone suddenly started acting like this. Clearly those idiots weren't capable of figuring it out. So I started messing with it.This is where we get to the most important line in this article, the one about what Apps are 'supposed' to do and how the App Review process catches errors and offenders. Actually, App Review seems to be the staffing pool for the Genious Bar.The reason the myth about Multitasking draining battery power is the quantity of truly crappy Apps which not only mess up battery life in the background but also play havoc with memory and mess up the performance of other Apps.Want to test this, get the App "ninjaSteve" which is intended to be a joke. Not only is it a literal joke, but hidden one as well; it's a demonstration of how bad code can whack things and how bad Apps can get through.Give it a try. Then Force Quit!!!
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Anyone with [a jailbroken phone] SBSettings (and a compulsion to go in to Processes and kill apps you no longer need, like me) knows the Multitasking Bar is really just a Recently Used collection. I was hoping Apple would improve the background handing of apps with iOS5, or add more memory to iPhone 4S to handle them better, but I was wrong.
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Yes anyone with a jabroke. iPhone cango into sbsettings and see that those apps aren't necessarily open. However you can also see the list of running process and see that a lot of them are still running in the background. And maybe it's supposed to free memory of previously used apps but anyone with a 3GS knows you often have to kill background apps in order to free memory so the app your trying to use works.
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Total BS. If your iOS device is jailbroken, use SBsettings to check your free memory. You will note that when apps are running in the background or "suspended" they take up the same amount of memory. I just tested with flipboard, it uses the same amount of memory after 20 minutes of inactivity. The moral of the story: Just because you think you know how it works, doesn't mean that you know anything. Shut down apps in the multitasking tray for more memory, and shut off your iOS device. These things will clear the memory properly.
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Josh,Do you work at the Genius Bar? It's about Battery life, he said the memory stayed until iOS takes it back.(by the way, I didn't deserve the pass for that typo!)
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To stop the app from running if it is running and the remove it from the recently used list.
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So I'm not an expert or anything but if it's not a true multitasking then isn't apple doing a false advertising?!!!
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this article does not cover my experience.On everyday use of my iPhone 4 I have about 60-80 MB RAm free (SBSettings shows this). If I launch a memory-intensive App (line PerfectlyClear) it tells me I have to little free memory and closes.... I quit all "multitasking" sh*t with RemoveBackground, have 300 MB RAM and can use the mentioned app without problems.I don't beleive this article, or at least state, that the whole concept doas not work as intended.
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meh. ill still remove the apps from the background bar when ive finished with them, just more organised.
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its still multitasking. you can use multiple apps at once, e.g listen to radio app and surf the web, facebook, game etcbut if the app is minimised/closed and isnt doing anything then the OS will stop it running and using power.
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I was helping someone with his iPad last month, it was lagging and taking forever to load web pages and apps. I opened the "multitasking" bar and he had 5 rows of apps in there. After removing them from the multitasking bar low and behold the iPad went back to its snappy self. Same thing happens with my iPhone (which isn't jailbroken by the way). If they're really not supposed to be running AT ALL after the home button is pressed then apple screwed up big time because all signs point to the opposite being true.
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Totally agree, just tried it.
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I think the developers need to install SBSettings to see how their software works.
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Something sounds off... I have my available memory showing in my status bar and why is that when I kill apps from that list I free up memory?
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I have been told by the Genius Bar folk some conflicting answers on many things, so I'm not sure I would trust them to do anything except get me a new piece of hardware from the store room.But I would have thought that any extra processing required to manage memory because of a suspended app will use power - probably very little. But if you NEVER close apps from the 'Multitasking' bar then I would expect that iOS is spending extra processing time to reallocate memory every single time you use an app. There's no way that wouldn't affect power consumption in some way... Perhaps its not that it uses power while simply sitting there locked, but maybe that it uses more power than it should switching or opening apps while using the device. Just a thought...However I think Josh's problem was definitely hardware and the Genius employees at his local apple store are a bunch of douchebags.
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Alex, you're taking far too seriously apple stores staff members. most of them are sales attendants with a nice t shirt ON & some knowledge base skills to pull out & quickly sort a question out. (it also depends on the country where you meet them tho still, a bunch of lucky bastards who got on board into a company of many parasites eating from the same cup & sharing it with the mind behind innovation, Steve jobs. until it lasts = until banks, customers, share-holders, financial institutions are going to realize that an unsatisfied customer is representing quite a bit of the market share & driving clients elsewhere. since it's a large cup at the moment they can afford to take on board mostly useless individuals, (time wasters) & waste their time in the same way they waste time of others.ideally refer to jailbreak community on the internet to understand what the backgrounding iOS feature is like & maybe try backgrounder too, a real BG tweak for iOS available in cydia allowing to unable & disable BG manually & allowing customization of BG behavior or recently used apps list. CONCLUSION:do not waste time and energy by getting angry at or frustrated about apple store's members of staff, we are already working on that by making pressure on Apple board members to change education & training policy also consider, in a difficult moment (the so called recession) employees have to be the crappy ones to save on HR costs. what they do in apple store is a sale, they gather whether there is someone still interested in buying something then , they sell a crap version arguing it's out of stock or unavailable at that time & , reserve in fact the good one for some good friends. lack of TRUST in themselves all across EU right now.marcello
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uh duhhh....apple already explained this when they 1st released ios 4, and have gotten tired of correcting misinformed people on this site.
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because the apps are cached in the memory....they arent "running" (using cpu). its saves the state of the app in the memory to keep track of where u left off, like a saved file from a game.
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zephyr is more of a smart-switching mechanism, not a task manager. And you would definitely switch between apps a lot
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Anyway , we all know that iphone apps are full of memory leak , that they do consume battery in suspended state and that's why such a tweak can be interesting but is even not enough , cause for the tweak to be perfect , it should kill all background apps task etc... and just after Free Memory as you can do it in SBSettings . I'm bored about seeing my memory going down and down over the day having to push the Free Memory button + task cleaner . There are indeed a lot of holes in the system and this can be afforded to developpers but mostly to Apple itself . I find this article a lil bit Apple Propaganda don't you ?Jacques Dupont(d)
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If someone tells you that all the apps in the multitasking bar are running, ** using up memory ** or sucking power, they are wrong.**If memory is becoming scarce, iOS will automatically move Suspended apps into the Not Running state and reclaim their memory.**So are the apps using memory when they are in the multitasking bar or not?I can tell you that when i open games and apps then close them, i loose alot of memory and it slows my iPhone down! Is this artical true or only half true?
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That's why I use springtomize 2 and go app switcher > app handling > hide inactive apps from switcher
