How to set a stronger iPhone passcode
Your four-digit iPhone passcode might be easier to guess than you might think. Thankfully, it's easy to set a longer and stronger passcode.
If your iPhone passcode is 1234, you might as well disable it. In fact, if it's in the top 10 of the most common iPhone passcodes, it's not really doing you a whole lot of good. To keep your iPhone secure should it fall into the wrong hands, you might want to think about choosing another four-digit code. Better yet, you can create a custom passcode that will make your iPhone much more secure. It's a snap. Here's how:
In Settings > General, choose Passcode Lock. On the next screen, you can choose to turn passcode on and select a four-digit number. Before you tap to Turn Passcode On at the top of the screen, look a few lines below and flip the slider next to Simple Passcode to OFF. Now, when you turn the passcode on, you'll be able to enter a code of any length that can include numbers, letters, and symbols.
As for the enterprising third-party app, Big Brother Camera Security, which collected data from 204,508 passcodes, , claiming it was "surreptitiously harvesting user passwords."