FWIW, it appears the device can crack at about 240ms per guess. That means a little over four guesses per second.
For a four-digit passcode (10,000 possibilities), that's only 40 minutes.
For a six-digit passcode (1,000,000 possibilities), it's close to three days.
Seven digits, as someone has suggested: almost 28 days.
For an eight-character password, assuming 95 possible characters*, it's over 50 million years.
The key point here being that it appears to be an online attack, so speed is limited by whatever the Secure Enclave allows (enforced 80ms delay) plus additional latency by its surroundings. Someone who still has an all-digit passcode should perhaps be slightly worried, though. (Leaving aside that I'm fairly confident Apple will fix this soon.)
*) 26 lower-case, 26 upper-case, digits, some special characters. In practice, I'm guessing iOS actually allows quite a few more than that, making it even harder to crack. But let's still assume these are the common characters to use in a password.
For a four-digit passcode (10,000 possibilities), that's only 40 minutes.
For a six-digit passcode (1,000,000 possibilities), it's close to three days.
Seven digits, as someone has suggested: almost 28 days.
For an eight-character password, assuming 95 possible characters*, it's over 50 million years.
The key point here being that it appears to be an online attack, so speed is limited by whatever the Secure Enclave allows (enforced 80ms delay) plus additional latency by its surroundings. Someone who still has an all-digit passcode should perhaps be slightly worried, though. (Leaving aside that I'm fairly confident Apple will fix this soon.)
*) 26 lower-case, 26 upper-case, digits, some special characters. In practice, I'm guessing iOS actually allows quite a few more than that, making it even harder to crack. But let's still assume these are the common characters to use in a password.