iOS App Crashes due to insufficient memory

Hi there, I am currently developing a mobile app with realistic graphics (something similar to the zen garden app). I am pretty new to UE4 and have been trying to learn on mobile development.

However, I am currently facing memory management problems. The application seems to be crashing after I open and stream 4-6 different levels depending on the size of the levels. Individually, the levels worked fine, but upon loading 1 after another the app crashes.

Below are a few things I have done to help relief in memory management:

  1. I have unload/unstream my levels before I open a new level
  2. I have removed all my UMG at the start of each new level
  3. I have garbage collect at the beginning of each new level

The performance seemed to improve. But crashing issue still happened. The diagnostics have shown to be a jetsam event which I read was a memory management issue.

I am asking if there are any good practices and helpful methods for mobile app optimization?

Thanks in advance.