iOS 9 uses new tricks to squeeze more battery life out of the phone you already own

Apple touted a number of flagship features of iOS 9 during its WWDC keynote, but the company is quietly focusing on squeezing more battery life out of the phone already in your pocket.

A session for developers titled “achieving all-day battery life” pushed that app builders need to be more conscious of how their code is draining the user’s battery and introduced new features to help catch battery thirsty apps.

One significant feature of iOS 9 that Apple hadn’t mentioned previously stops your iPhone’s screen from lighting up when it’s face down on a table. Until now, the iPhone would light up for every notification, regardless whether the screen was actually viewable or not.

In iOS 9, it’s much easier to keep track of what apps are draining your battery, how long you used individual apps and what they are doing in the background with the new battery menu.

Changes in iOS 9 also improve the way phone handles app activity in the background. The OS now intelligently saves some network activity for the next time you’re on Wi-Fi and defers heavier processing to when plugged in for charging.

A new warning indicator in XCode that details the energy impact of apps under development and what activities will cause the most battery drain, to make developers more aware of what impact they’re having.

Developers are being encouraged to move away from old methods of updating information in their apps, asking them to eliminate polling and timers when looking for new data. Apple instead recommends that work be performed in batches when the user is actually using the app.

When not in use, apps should now be at “absolute idle” in iOS 9, to reduce battery power as much as possible.

Overall, Apple says that iOS 9 already performs better on existing hardware with up to one extra hour of battery life. It’s spent a lot of time optimizing system apps for energy efficiency to squeeze as much as possible out of existing hardware.

With this release, it’s pushing developers to be more considerate of how much energy they’re actually using. It’s unclear if it’ll enforce new rules on the App Store that check app efficiency, but the push could mean major improvements for how long your phone makes it through the day.

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