Ellipsis
Actually - I have a PIN on my iPhone, but I've opted to go for a six digit number, not the usual four digit.
...but I only have to use that when I reboot my phone. Normally I open it with the fingerprint scanner.
So the scrote would either have to be standing right behind me on the off chance that I reboot my phone (unlikely)...and remember my six figure passcode (very unlikely). Alternatively, he or she could cut off my thumb (seriously unlikely), but ultimately - all this is moot...because when I'm out and about, my iPhone stay in my pocket, because I have an Apple Watch. If I get an email, text message or Facebook/Twitter notification, I check it from my wrist, rather than getting my phone out.
...of course, I say this with a smug look on my face, whilst I'm concurrently being burgled at home because the security on our house is no where near as comprehensive as that on my iPhone.