iOS App background process

To run background service, need to declared in info.plist file.

Add UIBackgroundModes key and set its value to array containing one or more of the following:

• audio—The app plays audible content to the user while in the background. (This content includes streaming audio or video content using AirPlay.)
• location—The app keeps users informed of their location, even while it is running in the background.
• voip—The app provides the ability for the user to make phone calls using an Internet connection.
• newsstand-content—The app is a Newsstand app that downloads and processes magazine or newspaper content in the background.
• external-accessory—The app works with a hardware accessory that needs to deliver updates on a regular schedule through the External Accessory framework. bluetooth-central—The app works with a Bluetooth accessory that needs to deliver updates on a regular schedule through the CoreBluetooth framework.

Point to note:
https://developer.apple.com/library/ios/DOCUMENTATION/iPhone/Conceptual/iPhoneOSProgrammingGuide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html