Unfortunately, that is a system feature of the iPhone and not something I can fix.
iPhones fully kills the game by refreshing the browser whenever the RAM usage increases or there's a lag spike in the game.
There is no fix for this, and the older the iPhone, the more often it happens.
So, iPhone is not a platform that can be supported at the moment.
The next update will have a low-quality setting for weaker devices that **might** help, but I can't guarantee.