I am working on the next version of an existing iPad app which has a pincode to lock admin functions. The current version has no means to override the pincode. We followed similar patterns and use cases as the iOS passcode lock feature to set the pincode and like iOS have no means to override the lock.

Is it bad that the lock cannot be overriden? What is best practise for a forgotten pincode in native apps where an email cannot necessarily be sent?

We are currently considering giving an option to remove the lock at the expense of deleting all the data. Users we have spoken generally agree this is a good compromise, but it seems to me to be a little harsh.

  • I guess I would tend to rather leave the definition of ‘harsh’ to my users :-) But anyway – maybe taking a step back might provide some further clues on how to deal with this best: why do you actually need to lock the admin features in the first place? What kind of irreversibly destructive effects might be unleashed by using them and who would be affected? Apr 21, 2011 at 2:23

2 Answers 2


I would definitely not go for the deletion of the data, it could result in a DoS by some malicious user which will perform the recovery on the purpose of deleting the data.

The solution proposed be kaarel is very similar to the windows way to recover the password. The secret question is a pretty common pattern to recover a password or pincode. But if you leave to the user the choice of the question/answer, it will end is some trivial guessing (many users chose the date of birth or the car plate, very easily recoverable informations). It all depends on how valuable are the information you are protecting with that pincode.

I would suggest to propose to the user a sequence of images/icons to remember to change the pincode. The sequence is recorded when the pincode is set. Usually the images are remembered better than numbers.

  • alor--curious about "images are remembered better than numbers". Can you refer an article?
    – nielsbot
    May 2, 2011 at 19:25
  • I don't have a specific article, but if you search for memory enhancements methods you will find a lot of article explaining how to memorize more data associating them to images and why an image is the base of memory. This is the same reason the car plates are made up of letters and numbers and not just numbers, letters like images are easier to remember than numbers. Try remembering '19283764' and 'brasegkf', which is easier?
    – ALoR
    May 2, 2011 at 19:46
  • well i'd argue that license plate numbers are just as hard to remember as numbers UNLESS in your mind you can combine some of the letters into symbols. In your example, for instance, I can remember 'brase' as a single (phonetic) symbol, so i'm only required to remember 4 symbols total: 'brase', 'g', 'k', 'f'. (guess this is tangential to your original point)
    – nielsbot
    May 2, 2011 at 21:45

How about registering a secret question-answer pair during the code selection process? Considering that compared to similar e-mail scenarios user is missing one tier of protection, the question should either be more difficult to guess (maybe choosable by user), or you could also use several questions to cancel the lock.

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