UDID and other device identifiers for iOS

When identifying a device for sending notifications, best practice is to use Channels over device tokens, so that you can reference an app installation, regardless of whether a push address is available.

See below for more information about the differences between the UDID, device token, and Channel ID.

UDID - (iOS Unique Device ID): 

The UDID is a number in each iPhone that is used by developers to distribute new apps directly into the phone for testing purposes before they are available in the App Store. UDIDs are used to create an Apple-certified provisioning file that is dragged with the app into iTunes.

The UDID is not visible on the phone. It has to be revealed in iTunes, and it cannot be highlighted and copied like normal text. To retrieve the UDID you would need to do the following:

  1. Connect the device to the computer, and run iTunes. 
  2. Select the device in the Device list. On the right side the device information will be visible.
  3. Click the Serial Number. It will switch to displaying the UDID. 
  4. Press Cmd-C to copy the UDID to the clipboard.
Urban Airship does not use the UDID for push notifications and cannot map a UDID to a Channel ID or Device Token for troubleshooting purposes.

Device Token:

A device token is an identifier for the Apple Push Notification System for iOS devices. Apple assigns a Device Token on a per-app basis (iOS 7 and later) which is used as a unique identifier for sending push notifications. Each device has two device tokens per app: one for development, and one for production (ad hoc or app store builds). The tokens are 64 hexadecimal characters.

 

Channel ID:

A Channel is an identifier generated by the Urban Airship SDK and provides a mapping to a given installation of your app on iOS, Android, and Amazon devices. With iOS 7, Apple drastically changed the way device tokens are issued, and to prevent a similar change from affecting our customers in the future, we create a Channel identifier for each installation which will map to an iOS device token if one is available. The Urban Airship Channel will remain the same even if the push address changes, and thus is a reliable abstraction for identifying installations. 

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