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

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

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!

Available from iOS 8.0

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.

Test your Swift today

Think you know Swift? My book Swift Coding Challenges will put your Swift skills to the test – it's perfect for job interviews and more!

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!

Click here to visit the Hacking with Swift store >>