An application that I am creating needs to start with the unlocking of the cell phone, is this possible?
How will you start the app, if the cell phone is locked ?
What do you want exactly? A security check system when user start the app in order to use the app?
If that is so you can do these steps
When user starts the app for the first time, you direct the user to define a pass code (save it to a tiny database) and then for the next time she/he starts the app he/she must enter that pass code in order to use the app. This is the basic logic.
you can use fingerprint sensor, and tinydb with text box for password or pin
no, what you are really looking for is that when you start the application or when you want to log in, the user asks me to verify the unlock pattern of the phone, or if you are using the fingerprint, etc…