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iOS Backgrounding - SLC Cocoaheads

Dave Stevenson
Dave Stevenson

The document discusses doing background tasks on iOS, which is limited to a few options. It can explain that apps can register to receive location updates, play audio, or perform VOIP tasks in the background by setting the appropriate value in the app's Info.plist file. The document provides code samples and demos for receiving location updates and playing audio in the background. Developers are warned that background tasks may drain the user's battery.

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Backgrounding Bursting Your Bubble on iOS
Sorry Doing what you want in the background is almost impossible
photo by protographer23
Get Your Notepads Ready Suspending vs. Resuming Local Notifications Doing Stuff in the Background
Exiting vs. Resume Since iOS 4, you can keep your app open on exit But its really just a freeze and resume - nothing happens while its in the background
Resume Me Set the UIApplicationExitsOnSuspend to NO in your Info.plist
App Delegate Events App Initial Load -> Exit: applicationDidBecomeActive applicationWillResignActive applicationDidEnterBackground On Relaunch: applicationWillEnterForeground
Sounds Promising applicationDidEnterBackground sounds promising, but you cant do anything inside it that is long-running. Docs say you have 5 seconds You cant get back to the UI
Terminate on Exit Set UIApplicationExitsOnSuspend to YES in your Info.plist
App Delegate Events App Launch -> Exit: applicationDidBecomeActive applicationDidEnterBackground applicationWillTerminate
Kill Me If the user does the jiggle and Red- Xes the app, no events are fired
DEMO!
Local Notifications You can schedule local notifications to prompt the user at a future time even if your app isnt running Useful - but remember the user isnt required to open the app, and your notification may never appear
DEMO!
Ok, Next So you can do things in the background, but its limited to 3 things: Get GPS updates Play Justin Bieber Do the VOIP
Set Your Plist Do do one of those 3 lovely things in the background, set the UIBackgroundModes in your Info.plist Values are: location, audio, voip
Location Get super duper real-time updates or major changes only Use CLLocationManager to do the magic
DEMO!
Playing Audio Its easy: start playing your tunes using AV* framework. If something else starts playing music, you lose
DEMO!
VOIP Sorry, no demo. But supposedly you can open a socket and keep it open.
Fighting the Man People have tried tricking the system by playing an empty sound file. This works until some other app plays sound. GPS Updates take up battery power, so your users may hate you.
Conclusion Read more at: http://developer.apple.com/library/ios/ #documentation/iphone/conceptual/ iphoneosprogrammingguide/ BackgroundExecution/ BackgroundExecution.html Sample Code: https://github.com/ dnstevenson/BackgroundTest Good Luck!
Thanks! Find me on Twitter @dnstevenson Buy one of my apps at http:// www.stevensonsoftware.com Leave me a 5-star review and Ill be your best friend

More Related Content

iOS Backgrounding - SLC Cocoaheads

  • 2. Sorry Doing what you want in the background is almost impossible
  • 4. Get Your Notepads Ready Suspending vs. Resuming Local Notifications Doing Stuff in the Background
  • 5. Exiting vs. Resume Since iOS 4, you can keep your app open on exit But its really just a freeze and resume - nothing happens while its in the background
  • 6. Resume Me Set the UIApplicationExitsOnSuspend to NO in your Info.plist
  • 7. App Delegate Events App Initial Load -> Exit: applicationDidBecomeActive applicationWillResignActive applicationDidEnterBackground On Relaunch: applicationWillEnterForeground
  • 8. Sounds Promising applicationDidEnterBackground sounds promising, but you cant do anything inside it that is long-running. Docs say you have 5 seconds You cant get back to the UI
  • 9. Terminate on Exit Set UIApplicationExitsOnSuspend to YES in your Info.plist
  • 10. App Delegate Events App Launch -> Exit: applicationDidBecomeActive applicationDidEnterBackground applicationWillTerminate
  • 11. Kill Me If the user does the jiggle and Red- Xes the app, no events are fired
  • 12. DEMO!
  • 13. Local Notifications You can schedule local notifications to prompt the user at a future time even if your app isnt running Useful - but remember the user isnt required to open the app, and your notification may never appear
  • 14. DEMO!
  • 15. Ok, Next So you can do things in the background, but its limited to 3 things: Get GPS updates Play Justin Bieber Do the VOIP
  • 16. Set Your Plist Do do one of those 3 lovely things in the background, set the UIBackgroundModes in your Info.plist Values are: location, audio, voip
  • 17. Location Get super duper real-time updates or major changes only Use CLLocationManager to do the magic
  • 18. DEMO!
  • 19. Playing Audio Its easy: start playing your tunes using AV* framework. If something else starts playing music, you lose
  • 20. DEMO!
  • 21. VOIP Sorry, no demo. But supposedly you can open a socket and keep it open.
  • 22. Fighting the Man People have tried tricking the system by playing an empty sound file. This works until some other app plays sound. GPS Updates take up battery power, so your users may hate you.
  • 23. Conclusion Read more at: http://developer.apple.com/library/ios/ #documentation/iphone/conceptual/ iphoneosprogrammingguide/ BackgroundExecution/ BackgroundExecution.html Sample Code: https://github.com/ dnstevenson/BackgroundTest Good Luck!
  • 24. Thanks! Find me on Twitter @dnstevenson Buy one of my apps at http:// www.stevensonsoftware.com Leave me a 5-star review and Ill be your best friend

Editor's Notes