An iPhone would explode trying to force a password...
Most password crackers try every single digit combination.
So first it tries a-z, 1-9. Then it does two digits, trying every single possible combination that thoese two could make, and so on with more digits. Which is exactly why long passwords, and capitalized passwords are near impossible to crack. It'd just take too long for a computer to try every combo.
Though people who use big, common words get cracked easy too, since there are password crackers that just use a gigantic list of common words.