Can I prevent an iOS user from changing the date and time?

Question

I want to deploy managed iOS devices to employees of the company, and the app they will use will timestamp data that will be recorded locally, then forwarded. I need those t

Answer 1

You cannot prevent the user from changing time.
Even the time of an Location is adjusted by Apple, and not a real GPS time. You could look at mach kernel time, which is a relative time.
Compare that to the time when having last network connection.

But this all sounds not reliable.