In the US, the police cannot compel you to unlock your phone with a passcode or a PIN. However, the police can compel you to unlock your phone with your fingerprint. I have an iPhone 6 Plus with iOS 8.4, and I normally use TouchID such that my fingerprint unlocks the phone. I want to disable the fingerprint and force the use of a passcode/PIN, and I want to do this quickly. Just in case. As far as I know, the only way to do this is to turn off the iPhone. After it powers off and on again, it requires the passcode. This is not very fast. Ideas?