Apple resolved this issue with the introduction of multitasking operating system iOS 4.With Multitasking, you can use more than one app at a time on your iOS device.
If you switch to another App by pressing the App icon, the previous app moves to background state.
The system handles those background Apps easily and sends them into suspended state after few minutes of inactivity.
In case of suspended state , User has nothing to do with that App. But,if the user wants to open the same application again,it will start from the same stage,where he left it.
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In this case,user can't resume the whole process again.But from developer's side,it can be accomplished by using Apple's background execution of tasks for finite-lengthy time.
iOS system can terminate the App in background anytime,if it gets low memory issue.