This app was mentioned in 1 comment, with an average of 1.00 upvote
Tire pressure depends on your weight plus the bikes total weight plus whatever you want to load unto the bike. For example me at 61kg with my bike at 10kg needs a rear tire pressure of 85psi wih 25Cx700C tires. The front tire can do wih less like 60psi unless you load the front with a handlebar bag or like me letting my freehub pawls scream as I descend slopes. In this case keeping the front tire at thr same pressure as the rear is pretty good.
I use his app to determine tire pressures based on rider weight, bicycle weight and load.
https://play.google.com/store/apps/details?id=com.edisongauss.bertotirepressure.demo&hl=en
I don't know if here is an iOS equivalent for this app.