juliengdt/lowpower_mode.md

## lowpower_mode.md

      
    Raw
  

              lowpower_mode.md
            
          
    Low Power Mode - LPM

With iOS 9 Apple added a Low Power Mode to the iPhone. It extends battery life by stopping some battery heavy features such as email fetch, Hey Siri and background app refresh until you can recharge the device.
It is important to understand that it is the user who decides to enter low power mode. You need to go into the battery settings to turn it on.
Detection

To detect LPM you have to be in the couple iOS 9.X / iPhone:

For iOS 8.X, you need test availablity before use it
LPM is a iPhone-only feature. If you call it on an iPad, it will return you always false

What to do

Reading Apple doc, there are some effects you might do on LPM, such as:

Stop location updates
Limit the use of animations
Stop background activities such as networking
Disable motion effects

More Reading


Energy Efficiency Guide for iOS Apps
WWDC 2015 Session 707 Achieving All-day Battery Life

Apple Guidelines

Your Obligation as a Developer
Even small inefficiencies in apps add up, significantly affecting battery life, performance, and responsiveness. As an app developer, you have an obligation to make sure your app runs as efficiently as possible. Use recommended APIs so the system can make smart decisions about how best to manage your app and the resources it uses. Whenever possible, batch and reduce network operations, and avoid unnecessary updates to the user interface. Power-intensive operations should be under the user’s control. If a user is playing a graphics-heavy game, for example, the user should not be surprised if the activity consumes power. Strive to make your app absolutely idle when it is not responding to user input.
By adhering to recommended guidelines, you can make big contributions to the overall energy efficiency of the platform and the satisfaction of your users.

  
## lowpower_mode.swift

// One-Shot Detection
if NSProcessInfo.processInfo().lowPowerModeEnabled {
  // stop battery intensive actions
}


// Better Detection, ie in the viewDidLoad of your viewController or in the AppDelegate

// Observer
NSNotificationCenter.defaultCenter().addObserver(self,
  selector: #selector(didChangePowerMode(_:)),
  name: NSProcessInfoPowerStateDidChangeNotification,
  object: nil)

// Associated function
func didChangePowerMode(notification: NSNotification) {
    if NSProcessInfo.processInfo().lowPowerModeEnabled {
      // low power mode on
    } else {
      // low power mode off
    }
}

	// One-Shot Detection
	if NSProcessInfo.processInfo().lowPowerModeEnabled {
	// stop battery intensive actions
	}


	// Better Detection, ie in the viewDidLoad of your viewController or in the AppDelegate

	// Observer
	NSNotificationCenter.defaultCenter().addObserver(self,
	selector: #selector(didChangePowerMode(_:)),
	name: NSProcessInfoPowerStateDidChangeNotification,
	object: nil)

	// Associated function
	func didChangePowerMode(notification: NSNotification) {
	if NSProcessInfo.processInfo().lowPowerModeEnabled {
	// low power mode on
	} else {
	// low power mode off
	}
	}