We all know apple always look for privacy. So i think if turning off a iphone need passkey that is best. Cz if someone steal my iPhone he/she immediately turn off the phone first . But if there is passcode option he/she can't switch off the phone. So i have more time to find my phone or call my phone number for arguing. Same passcode facility also applicable for restarting process too. I request to ios developer add password option for turning off or restarting the iphone . Thank you . (Sorry for bad english)