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

How to detect when the system is under pressure and you should reduce your work

Swift version: 5.2

Paul Hudson    @twostraws   

You can – and should – read the thermal state of your device before doing any intensive work, because if the system is already under pressure you might find your app becomes unresponsive, even with basic things like animations.

You can read the current thermal state using ProcessInfo.processInfo.thermalState, which has four values:

  • When it’s .nominal you can proceed as normal and do all the work you want.
  • When it’s .fair you should consider delaying any work that isn’t visible to users.
  • When it’s .serious the system is working at high capacity and you should scale back the CPU, GPU, and I/O work you do.
  • When it’s .critical the system is unable to keep up with all the work that is being done, so your user interface is likely to stutter – now is a bad time to do any sort of animation.

The latter two of those are important to monitor, because users will notice – at .critical level you can expect their device to be hot to the touch, so hopefully your app isn’t the cause of that!

Hacking with Swift is sponsored by NSSpain

SPONSORED Announcing NSSpain 2020: Remote Edition! An online, continuous conference for iOS developers. We’ll start on Thursday and finish on Friday, with talks, activities, and lots of fun for 36 hours, non-stop. Sound good? Join us!

Find out more

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

Available from iOS 8.0

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!

Link copied to your pasteboard.