Resume app from where it was sent to background.

I have an iOS app in which user can rate and write review for the item. Suppose I write review and do not press submit button, then I send my app in background. When I open my app again after 10 - 20 minutes, it shows splash screen again and opens Home Screen like it was killed. How can I prevent this and resume my app from the review screen. Due to this the review is also lost.