Here are a couple of tips for securing your iPhone. They're very easy and should be pretty obvious, but most people don't do them.
Yesterday, Alex lost her iPhone on the street in Toronto. She dropped it on the sidewalk outside of the optometrist's office. It took her about half an hour to realize that it was missing. She phoned me to let me know as soon as she realized. I immediately pulled up Find My iPhone on my iPad and started looking for it. Unfortunately, it was offline already. Either, it was broken, or someone found it, and took it offline on purpose, using airplane mode or simply turning it off. I immediately turned on Lost Mode. This allowed me to set a passcode on the device and display a message on the screen asking whomever finds it to call me. Unfortunately, in order for these actions to work, the phone has to be connected to the internet or reconnect at some point before the finder (thief) manages to do a full reset and wipe everything, including iCloud off the phone. These features work through iCloud, and someone can reset your iPhone to factory settings if you haven't set a passcode (which Alex hadn't). If you have a passcode, the phone can't be reset without entering the code.
Tip 1: Turn on Find My iPhone
Tip 2: Use a passcode or Touch ID
So, for the next hour, I watched my iPad to see if the phone would come back online, and it didn't. I was convinced that someone had reset the phone and Alex would never see it again. It was an iPhone 5 in pretty much mint condition, so it could easily fetch $400 on Kijiji. However, about 90 minutes later my phone rang. It was a lady in Toronto, who went on to tell the story of how she had bought the iPhone off some guy on a street corner for $100. Really? Who randomly buys an iPhone on a street corner while you're just walking around? Obviously, the price is too good to be true. And weren't the girly case and pictures of young children in the camera roll a sign that maybe this phone didn't belong to the man who was selling it?
I didn't grill the lady for all the details, but from what I could piece together, she bought the phone about 20 minutes after Alex lost it, and then turned if off and went home. When she turned it on later, the phone locked up on her (because of Lost Mode) and she couldn't do anything except phone me to tell me she'd accidentally bought Alex's stolen phone.
In the end, Alex got pretty lucky. She got her phone back without too much hassle, but it could have been much worse. Find My iPhone and Lost Mode are awesome features, but they are rendered almost useless if you don't have a passcode on your phone to begin with. It might seem like a hassle to have to enter a passcode every time you wake your iPhone, but it isn't just a phone. It's a computer in your pocket. And it probably has most of the details of your life (email, contacts, passwords, etc.) on it. If it fell into the hands of someone who knew what they were doing, you could be in big trouble. Or, at the very least, they could wipe your phone and you'd never see it again.