You don't need to close apps on your iPhone (AAPL)

This myth that it does has persisted for years. Apple blogger and podcaster John Gruber said earlier this week it's the "single biggest misconception about iOS," the software that iPhones run on.

Apple has also busted the myth. Executives have said in emails that swiping apps off the screen doesn't help your iPhone's battery life.

Last year, Apple fan Caleb sent an email to CEO Tim Cook asking, "Do you quit your iOS multitasking apps frequently and is this necessary for battery life?"

Craig Federighi, the head of software development at Apple, replied: "No and No. :-)"

9to5Mac has a copy of the email.

The myth that closing unused apps can save battery life has been long-running and pernicious. It's widely believed, and it has even been suggested by reputable publications as a tip.

That has led to the popular habit of swiping to close the apps in the multitasking window until it's entirely empty.

The misconception has been debunked several times, but former Apple technician and MartianCraft CEO Kyle Richter wrote a great and detailed explanation earlier this month about why closing unused apps could actually hurt your phone's battery life.

Many people think that force-quitting these apps will at the very least do no harm since "they aren't running anyways." The logic of "…you might as well quit, just in case" comes into play ...

The very process of quitting an app will use up a measurable amount of battery life. There are times when the device may need those resources and it will quit the app on your behalf, which will drain the battery in the same fashion. However, modern smartphones have an abundance of memory and you would be surprised how often an app can just stay suspended forever. This is doubly true for any app that you are frequently launching and using, these apps in all likelihood will never need to be closed and the repetitive exiting and relaunching can have a very noticeable toll on your battery life.

Federighi obviously didn't go into the same level of detail as Richter, but he clearly has a great grasp of how iOS works, and his word should be considered the final one on closing unused apps.

So the next time you have an Apple rumor you want busted, you might try shooting an email to an Apple executive. They might just respond.