You've got a couple options...
1) On your host file set up a privilege set and account that has only permission to run a single "Re-Login" script. The file should be set to open to that account by default. On opening your iOS file, run a script that displays a custom dialog to capture the username and password the user wants to use in the host file. From that script call the "Re-login" script in the host file passing the username and password as a parameter.
2) You could also allow users to "authorize" their devices. One downside would be all authorized devices would be using a single account. But as long as a user's iPad has been verified, they won't have to log in again (or only after a day or week). You'd need a table to hold the Persistent ID of a device, and some scripts for the login, authorization, and de-authorization of devices, but users love it.
Also, make sure your iOS opening script closes itself after opening the host file and then you shouldn't be asked to log in to the iOS file again after it opens the host.
Thank you David, that sounds like a great solution to my problem. I'll give option 1 a go this morning.
Have you used this method yourself?
Sounds like you've used option 2 before, but it is more complex and will take me more time to set up, so....
I'm not sure what the protocol is, but I don't wish to be rude.
I've not responded further only because I've not yet had a chance to try it out.
Thankyou David, option 1 has worked out very well!!