UIDevice uniqueIdentifier deprecated - What to do now?

Question

It has just come to light that the UIDevice uniqueIdentifier property is deprecated in iOS 5 and unavailable in iOS 7 and above. No alternative method or pr

Answer 1

A working way to get UDID:

1. Launch a web server inside the app with two pages: one should return specially crafted MobileConfiguration profile and another should collect UDID. More info here, here and here.
2. You open the first page in Mobile Safari from inside the app and it redirects you to Settings.app asking to install configuration profile. After you install the profile, UDID is sent to the second web page and you can access it from inside the app. (Settings.app has all necessary entitlements and different sandbox rules).

An example using RoutingHTTPServer:

import UIKit
import RoutingHTTPServer

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var bgTask = UIBackgroundTaskInvalid
    let server = HTTPServer()

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        application.openURL(NSURL(string: "http://localhost:55555")!)
        return true
    }

    func applicationDidEnterBackground(application: UIApplication) {
        bgTask = application.beginBackgroundTaskWithExpirationHandler() {
            dispatch_async(dispatch_get_main_queue()) {[unowned self] in
                application.endBackgroundTask(self.bgTask)
                self.bgTask = UIBackgroundTaskInvalid
            }
        }
    }
}

class HTTPServer: RoutingHTTPServer {
    override init() {
        super.init()
        setPort(55555)
        handleMethod("GET", withPath: "/") {
            $1.setHeader("Content-Type", value: "application/x-apple-aspen-config")
            $1.respondWithData(NSData(contentsOfFile: NSBundle.mainBundle().pathForResource("udid", ofType: "mobileconfig")!)!)
        }
        handleMethod("POST", withPath: "/") {
            let raw = NSString(data:$0.body(), encoding:NSISOLatin1StringEncoding) as! String
            let plistString = raw.substringWithRange(Range(start: raw.rangeOfString("")!.endIndex))
            let plist = NSPropertyListSerialization.propertyListWithData(plistString.dataUsingEncoding(NSISOLatin1StringEncoding)!, options: .allZeros, format: nil, error: nil) as! [String:String]

            let udid = plist["UDID"]! 
            println(udid) // Here is your UDID!

            $1.statusCode = 200
            $1.respondWithString("see https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/iPhoneOTAConfiguration/ConfigurationProfileExamples/ConfigurationProfileExamples.html")
        }
        start(nil)
    }
}

Here are the contents of udid.mobileconfig:

    
        PayloadContent
        
            URL
            http://localhost:55555
            DeviceAttributes
            
                IMEI
                UDID
                PRODUCT
                VERSION
                SERIAL
            
        
        PayloadOrganization
        udid
        PayloadDisplayName
        Get Your UDID
        PayloadVersion
        1
        PayloadUUID
        9CF421B3-9853-9999-BC8A-982CBD3C907C
        PayloadIdentifier
        udid
        PayloadDescription
        Install this temporary profile to find and display your current device's UDID. It is automatically removed from device right after you get your UDID.
        PayloadType
        Profile Service
    

The profile installation will fail (I didn't bother to implement an expected response, see documentation), but the app will get a correct UDID. And you should also sign the mobileconfig.