A little inspiration from the loss of my friend's phone in the street. It has been stolen by one thief actually. However, we failed to track it down by "Finding my phone" since the thief shut down the phone. Hence, to avoid this to always happen in our life, I think it would be interesting to develop one new system to complete the security guarding which indicates the Face ID might not only be required to turn on the phone, but also to power off the phone. Moreover, for instance, after three trials of wrong Face ID, we can demand the system to ring to remind the users that their phones get stolen. Hope it would useful for the new development of software in coming iPhones. I am looking forward to seeing the next generation of iPhone :)