I'm working on an iOS Cocoa app that has a fallback - if the user doesn't enter a certain piece of data, the device's UDID is used instead, as a default. I need to add a check in our server code (written in Ruby) to recognize whether the value being sent up is a UDID (the user's default) or a custom string that they've set.
It seems that the right solution to my problem is a regular expression. I'm comfortable writing regex'es, but I need to be certain that this regex is 100% guaranteed to recognize a UDID.
I retrieve the UDID in code using:
[[UIDevice currentDevice] uniqueIdentifier]
And in the simulator, I get back this value:
6938CA7D-ECE2-53A4-B293-961A8D07AFB1
From this I might infer that I can just search for a string of hex characters that matches the pattern 8-4-4-4-12. But I want to be certain this works for every UDID.
I can't find anything about this in Apple's documentation and was wondering if anyone could give me a definitive answer to this question... thanks!
Why not send another bit of data indicating that it is a UDID? Or just use a different parameter name (UDID=6938...).
Then, in your server, you can test it like so if you really want to:
# somewhere outside the controller action, maybe the top of the file
UDID_PATTERN = /\A[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}\Z/
# inside the controller action you're sending info to
udid = params[:UDID]
if udid && (udid =~ UDID_PATTERN)
# do something with the UDID in place of the other
# bit of info they could have provided
end