I am just posting some information that was already spelled out in Daniel Amitay’s blog here.
I want to reiterate that just having a passcode lock your phone regardless if its an iphone or an android, is not enough if you use the following passcodes:
These are known as the most common lock codes and they will most certainly be the first codes someone will try to use if your phone ends up in the wrong hands. The reason why 10 is an important number is that some phone can be set to erase the personal data after 10 unsuccessful attempts.
Check out this graph: