Principles from WWDC 2014 Session 710 and 712 in iOS development. To save your battery life is major concern since user could check the battery usage in iOS8. Those battery master will be deleted forever, and you are no longer be able to blame the reason of draining on other apps (Map/Facebook).

1. Writing Energy
Efficient Code
2014 Session 710 & 712

2. What Uses Energy?

3. Concept
Coalesce work
Cut down wakes

6. “To sleep is the prepare for
the longer journey ahead”

7. Preview

8. Do It Never

9. Do it never
Respond to changes in active state
• Avoid unneeded work

10. Do it never Location
“Stop Location Updates”

11. Do it at better time
Let the system schedule work
• NSURLSession Background
Session
• Understand requirements
• Overhead cost

12. Do it at better time NSURLSession - Discretionary Tasks

13. Do It at Better Time

14. Do it at better time Networking
• Network conditions Throughput
• Reduce data sizes Quality, Compress
• Avoid redundant transfers Caching,
Resumable
• Handle errors Timeout, Retry

15. Do It More Efficiently

16. Do it more efficiently
Specify QoS classes on your work
Quality of Service NSOperation and NSOperationQueue

17. Do it more efficiently Quality of Service
• Specify the responsiveness and
energy requirements of work.
• Classify long-running or resource-intensive
operations in your existing
code.
• Aim for >90% of time at Utility or
below when the user is inactive.

18. Do It Less

19. Do it less
Optimize and improve your resource use
• Reduce CPU Use minimize timers
• Performance Unit Test (Prince)
• Limit Screen Updates
• Visual effects avoid placing over updates elements
• Minimize your I/O

20. Do it less
Notifications
• Device will wake for notifications
• Set Push notification priority

21. Summary
“Be a considerate
background app”

22. Related
2013 Session 712 Energy Best Practices