Can somebody explain the iOS attack?
It doesn't make sense. A long string of all possible PINs is supposed to be "cut up" by the "passcode check" function.
For example let's have this:
"1234567890 ..... 0980934720754055 ...."
This string is supposed to be cut up into:
1234 5678 9012 ....0980 9347 2075 4055 ..."
when it is fed into the iPhone because each four characters represent a passcode that should be checked and, consequently, attempt counter increased.