uniqueidentifier

I use iphone UUID for checking user's device is unique. I already know UUID will be changed when reinstall app. But, I have a question. Then, when app updated, UUID for my app will be changed? If UUID changed when app updated, where can I save UUID in iphone permanently(or same effect)? Save out your created UUID into user preferences for the app, which should be backed up - if they restore the app from a backup you'll get back the UUID. If you want to be even more sure you can get back the same UUID, save the generated UUID into the keychain - the keychain is kept intact even after you delete

I'm relatively new to Backbone and Underscore and have one of those questions that's not really an issue - just bugging me out of curiosity. I built a very simple app that allows you to add and remove models within a collection and renders them in the browser. It also has the ability to console.log the collection (so I can see my collection). Here's the weird thing: the ID's being generated are 1,3,5... and so on. Is there a reason specific to my code, or something to do with BB/US? Here's a working Fiddle: http://jsfiddle.net/ptagp/ And the code: App = (function(){ var AppModel = Backbone

I receive bytes from an RFID reader when presenting a card, but I'm unable to figure out how to derive the card ID from these bytes. For example, I have a card that has these numbers printed on it: 0007625328 116,23152 . I would expect that this is the ID of that card, right? For this card, I get the following bytes from the reader (in hexadecimal representation): <42><09><01><74><00><74><5A><70> . The decimal number 0007625328 translates to 0x00745A70 in hexadecimal representation. The number 116,23152 is actually a different representation of that same value (0007625328): 116 in decimal is

I want to generate 64 bits long int to serve as unique ID's for documents. One idea is to combine the user's ID, which is a 32 bit int, with the Unix timestamp, which is another 32 bits int, to form an unique 64 bits long integer. A scaled-down example would be: Combine two 4-bit numbers 0010 and 0101 to form the 8-bit number 00100101 . Does this scheme make sense? If it does, how do I do the "concatenation" of numbers in Python? sykora Left shift the first number by the number of bits in the second number, then add (or bitwise OR - replace + with | in the following examples) the second number

I need to generate unique ids for my application and I am looking for suitable algorithms. I would prefer something like this -- YYYY + MM + DD + HH + MM + SS + <random salt> + <something derived from the preceding values> F.ex. - 20100128184544ewbhk4h3b45fdg544 I was thinking about using SHA-256 or something but the resultant string should not be too long. I could use UUID but again, they are too long and they are guaranteed to be unique on only one machine. I would welcome suggestions, ideas. My programming language is Java. Edit: The ids need not be cryptographically secure. I am looking at

The problem is as follows - there's a university campus wide wifi connection with a single SSID, say "campus-wifi". The user freely roams around campus, and the usual hand-off between access points occurs. My question is, is there any information at any layer of the network stack that allows the client to identify (any unique identifier is fine) the specific access point they're connected to, rather than simply the fact that they are connected to "campus-wifi"? If it's relevant, I'd like to be able to do this from mobile devices (android/iOS primarily). You can get the BSSID of the access