Time was, a fellow wouldn't even wear his watch on the subway. Nowadays, every Tom, Dick and Harry has an Apple device in his lap. As this ridiculously-scored PSA for the New York MTA makes clear, this is not a good idea.
The MTA's suggestion to avoid device theft is just not using them during your commute, which seems like a drain on productivity and fun. A developmental iPhone case, the Adappt XT, offers another course of action.
Currently seeking funding on Indiegogo, the Adappt XT includes a flip-out 1.5-inch blade and claims to be the world's first iPhone case multi-tool. The promotional video really couldn't be further from recalling an urban situation, but combining New York City's number-one subway theft target with a built-in knife seems like a volatile mix. Perhaps they could consider pepper spray instead?
Top image: Adappt XT.