NEW: Subscribe to Hacking with Swift+ and accelerate your learning! >>

How to read the battery level of an iPhone or iPad

Swift version: 5.2

Paul Hudson    @twostraws   

iOS lets you track the battery level and status of the device you’re running on, which is helpful if you’re overlaying some sort of battery indicator over your user interface. You could even write a trivial app to detect power outages just by plugging in a spare phone then waiting for the charge state to change.

To get started, first enable the isBatteryMonitoringEnabled property of the current device, like this:

UIDevice.current.isBatteryMonitoringEnabled = true

You can now read the current battery level as a value between 0.0 (flat) and 1.0 (fully charged) using this:

let level = UIDevice.current.batteryLevel

If you want to be notified every time the battery level changes you can register for the UIDeviceBatteryLevelDidChange notification (sent up to once a minute), and you can also register for UIDeviceBatteryStateDidChange notification to see when the charge state changes. Both of those require isBatteryMonitoringEnabled to be enabled.

Hacking with Swift is sponsored by Fernando Olivares

SPONSORED Ever ask for help and your reviewer immediately notices issues you missed? Fernando Olivares is a 10-year veteran from Big Nerd Ranch and Lambda School who can help hone your app building skills, and he's just launched a new book that does just that – use the code "hacking" to save $5!

Buy the book

Sponsor Hacking with Swift and reach the world's largest Swift community!

Available from iOS

Similar solutions…

About the Swift Knowledge Base

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

BUY OUR BOOKS
Buy Pro Swift Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift (Vapor Edition) Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Server-Side Swift (Kitura Edition) Buy Beyond Code

Was this page useful? Let us know!

Average rating: 3.7/5

Link copied to your pasteboard.