Recently there was a brief scare for iOS users where Matthew Hickey, co-founder of security firm Hacker House claimed that iOS was susceptible to a brute force attacks. However thankfully it seems that might not be the case as in a statement made to AppleInsider, the company said, “The recent report about a passcode bypass on iPhone was in error, and a result of incorrect testing.”
Basically Hickey had initially suggested that there was an exploit that allowed the hacker to send passcodes over Lightning to a locked iPhone. This will be sent as one consecutive string without spaces and would contain all possible combinations from 0000 to 9999, or 000000 to 999999. This method was said to be able to bypass delays in between incorrect passcode attempts.
That being said, Hickey has since followed up with an update in which he admits that maybe the hack would not have functioned as he had initially thought, so for now iOS users can rest assured that that particular hacking method is not possible.