react-native-flat-button | Flat button component | iOS library

I have a signup form working great, fine ! But I want to make a boolean field : "terms" and I want that when it's clicked, it allows you to validate the form. But when not clicked, you can't sign up. I don't know how I can manage to do that.

My idea was to make a condition "if terms are accepted then => the form is validated and you can go to your account". It seems to me that it's the right way to do it but I don't know how I can do that. Maybe in creating a const terms as I did for Email, phone and password, but how to write that it must be validate to signup ? maybe with something like "accepted false" in the state but I don't know how to passe the "accepted" options in the field "terms"...

Thanks for any help.