Its not necessary because the system is designed to free up resources as and when it needs to. Many apps are often in a suspended state and not using any memory anyway.
because contrary to what most people believe closing all apps is bad for your battery life. when you close an app the phone uses more battery and resources next time you launch it, whereas if you leave it in the app switcher it's in a dormant state and when you launch it your phone won't work as hard to bring it up. So its ok to swipe up and close an app you wont be using for a while but if you have something that you keep going back to throughout the day its better to just keep it open.
How do you know they are using up your battery life?
source?Why would you want to close them all and make your battery life worse?
I did not know this. That's why edited my post.How do you know they are using up your battery life?
If they are suspended and not using any background services then battery impact will be minimal to none. All you are doing is removing them from memory and increasing the battery usage required to relaunch the app - if you are regularly killing apps you use on a regular basis this will be affecting your battery life even more.
The system will remove suspended apps from memory as and when it needs to - it will prioritise more popular apps over less used apps when purging. Trying to do a better job of memory management than the OS is pointless.
Useful if a buggy app stops working properly and you want to kill it and force a restart, or if you simply want to remove apps from the recently used list, but thats about it. It can occasionally be useful if you want to kill an app that is using a background service but if its causing you regular problems you would have better success in disabling background services for that app in Settings.
There is so much written about this, just google. Here is a few articles on the subject. First one is from an Apple ex-employee.source?
http://lifehacker.com/quitting-apps-in-ios-actually-worsens-battery-life-15600868343. Stop quitting your apps in multitasking
Most people tell you that closing your apps will save your battery life because it keeps the apps from running in the background. However, this can actually make your battery life worse if you do it on a regular basis.
By closing the app, you take the app out of the phone's RAM, so when you open it again your device has to load it back into memory all over again. All of that loading and unloading puts more stress on your device than just leaving it alone.
The truth is, apps in your multitasking menu are not running in the background at all: iOS freezes them where you last left the app. Unless you have enabled Background App Refresh, most of your apps are not allowed to run in the background.
No, the ability to close an app from the tray is to fix an app that has become unresponsive.