App crashes every after few scan with image/screen capturing

Vuforia SDK Version: 4.0 - Description with steps to reproduce: Hello, I am developing one iPad app with Vuforia 4.0 SDK where I am capturing/screenshot AR screen and saving that image into iPad Library. I have successfully implemented this feature but app crashes every after few screen capture. App Flow: When app opens it directly loads AR screen. Where you can see capture (red circle) button at bottom. By pressing on that you can take snapshot of current AR screen. It will save it in your iPad Library. And redirect you on another screen, From where you can come back to AR screen and can another snapshot. Problem: It is working only up to 20/25 times. After that when we press back button it will redirect us to AR screen and crash immediately. Again on new start app will work 20/25 times.  In memory spike it shows memory consumption increases and app crash after few successful iteration. Let me know if you need any more details. Can you please check why app crash on AR screen? Thanks in advance for your help. - Development OS (Mac OS X, Windows, Linux): Mac OS X - Mobile OS and Version: iOS 8.1.1 - Mobile Device Manufacturer and Model name: iPad Air 1 - Do the Vuforia Sample Applications show the same behavior?: I have added image capturing code in the Vuforia Sample Application and faces the same behavior.