Mastering iOS Frameworks: Beyond the Basics, Second Edition

17. Working with Background Tasks

When iOS was first introduced in 2008, only one third-party app at a time could be active—the foreground app. This meant that any tasks that the app needed to complete had to finish while the app was in the foreground being actively used, or those tasks had to be paused and resumed the next time the app was started. With the introduction of iOS 4, background capabilities were added for third-party apps. Since iOS devices have limited system resources and battery preservation is a priority, background processing has some limitations to prevent interference with the foreground app and to prevent using too much power. An app can accomplish a lot with correct usage of backgrounding capabilities. This chapter explains ...