NEW! Master Swift design patterns with my latest book! >>

How to detect low power mode is enabled

Paul Hudson       @twostraws

When a user has enabled low-power mode you probably want to avoid doing CPU-intensive work: not only is the system less able to give you resources, but you always want to respect the user's wishes and help their battery last as long as possible.

There are two ways of checking for low-power mode: you can read a property whenever you need it, or register for a notification. First, here's an example with the property:

func doComplicatedWork() {
    guard ProcessInfo.processInfo.isLowPowerModeEnabled == false else { return }

    // continue doing complicated work here
}

You can also register to be notified when the lower power mode state changes, like this:

NotificationCenter.default.addObserver(self, selector: #selector(powerStateChanged), name: Notification.Name.NSProcessInfoPowerStateDidChange, object: nil)

When that method is triggered, you can check the new value of isLowPowerModeEnabled to see what state the device is in:

@objc func powerStateChanged(_ notification: Notification) {
    let lowerPowerEnabled = ProcessInfo.processInfo.isLowPowerModeEnabled
    // take appropriate action
}

Available from iOS 9.0

Did this solution work for you? Please pass it on!

Other people are reading…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

Build for watchOS

Take your existing Swift skills to Apple's tiniest platform – check out Hacking with watchOS!

MASTER SWIFT NOW
Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Practical iOS 11 Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Average rating: 5.0/5

Click here to visit the Hacking with Swift store >>