Well, i guess that is the best solution for any game on a mobile phone, in case it doesn't work, just go on and reinstall it. However, there must be a real issue why the game crashes. I got the same issue with a lot of games, i thouht it is a problem that is only face by the iphones. However it is not like that. i remember, i been also playing minecraft on my iphone x, and as soon as i was entering my server, the game was crashing everysingle time. As soon as i got a proper server hosting in https://ggservers.com the issue was solved. So, in case you playing online, the issue might also be with the servers.