And the default ssh port is 22 as well. Though I don't think the iOS app should be prompting you to enter details if all 3 of these items are on their defaults. It's still worth a shot though.
If that doesn't do it, you should confirm whether SSH is actually running on your pi -- I think in one of the recent OS updates they started disabling it if you leave the password of 'raspberry' since its a security risk. You can enable SSH if it's currently disabled by running the command:
then going to Advanced Options > SSH on the menus that appear. It will then display a menu where you can toggle the SSH server state and save settings.