Why the app would be restart after pause?


I find that after the app was paused by the user (move to the background) ,
sometimes it would be restart.
Say the last view state by the user is A and the initial state ($urlRouterProvider.otherwise(‘B’)) is B.
After some hours, the app would be bring to B in iOS.
Did the ios clean the memory due to idle in the background?or any other reason?


Sounds like iOS doing some memory management to me.