Most Smart phones can be set to delete all data if an incorrect password is entered 10 times.
You can also backup all of your info to your PC or online with an Android phone so you can easily recover the deleted data, contacts, pics, apps, etc...
I believe same with iPhones but I no longer own those overpriced Apple phones and have owned Android OS based smart phones for the past few years.
Schedule the app to automatically backup your phone every day, week, month or how often you want and put a password on it.
If the cops demand you show them what’s on your phone, tell them to get a warrant or to go pound sand.
BTW, Metro PCS is a pay as you go provider and has great prices on current phones, unlike some of the outdated phones other carriers have.
Some smart phones with the current Android OS, 4.4, are free after rebate like the LG Optimus L70: