Engineers at Apple are smart so never let run anything in the background and allow to drain battery easily. Unfortunately, their good intentions are contradicting with marketing policies where people love to have multitasking devices where many things running in background.
In due course, they have introduced APNS (Apple Push Notification Services) that allows apps to be notified when something attention seeking going on and notify for that even immediately without considering whether that particular relevant app is running or not.
Background Fetch—A New FeatureHowever, this arrangement was not sufficient in social media age where Facebook like apps receiving constant updates and would like to appear with them when they are bringing at front-end/on the screen. Therefore, Apple has to introduce another features that can fulfill such regular updates demand in background and it has introduced a new feature named Background Fetch.
Background Fetch—At the Mercy of System, not by iPhone App Development Team
Technically we all are familiar with word Fetch very well so in simple words these real-time fetching of data take place at predetermined intervals in background. Unfortunately, we don't have direct control over background fetching through coding by iPhone app development team. No doubt, with efficient coding and smart parameter setting, we can show that we are good citizens to have background fetch for our applications so let's see how we can do it.
Factors Determine Background Fetch Frequency
As background fetch frequency is decided by system and it depending on some obvious factors, if we control them we can grab opportunities easily. For instance, network connectivity is one of the factors and system records that whether connectivity is available at particular time when it seeks to take place background fetch.
The second factor is to know about awakening of device status, if device is in sleeping mode so why system has to take background fetch at that time? Finally, system determines your previous history of background fetching and see how much data downloaded and how much time consumed by your particular application. As system hardly allows more than 30 seconds for background fetching so calculating data and time is natural for efficient background fetch candidate apps.
If you want to test the background fetch implementation, you have to create an application in Xcode and after selecting its name click of Capabilities Tab. Now, turn on the Background Modes capability and expand it further to check the button against the Background Fetch item. After saving this project simulate the background fetch for this application.
You will receive an Output window after pressing Cmd+Shift+C shortcut keys in your iPhone app development project. In printout you will find two statements, one for starting of background fetch time and another for ending time.