| Aliases have been superseded by Named Users. Please visit The Named User section of our Mobile Data Bridge Primer for more information. |
How Aliases work
Aliases are meant to track a single end user on the same mobile app across a small number of devices.
For instance, a user may have the same app on their Android phone, iPad and iPod touch. You want to send them the same notification easily on all three devices.
When the user signs in to your app, you may register an Alias with Urban Airship as a cryptographic hash of their email address or username. This would allow all places the user is signed in to be messaged with a single request.
| Do not send Personally Identifiable Information (PII) to Urban Airship for the purpose of setting Aliases or for any other reason. |
Be careful not to overwrite Aliases
There is no need to track sign ins or installations on your end for this purpose. When a new Alias is set by the mobile app, it will overwrite and remove any previous aliases. This makes targeting users quite easy if users are likely to sign in to and out of the mobile app. In addition, each registration call made from the mobile app to Urban Airship must include the Alias value or the Alias will be removed from the device.
Avoid registering more than 10 devices to an Alias
Aliases work best when they have 10 or fewer devices registered to them. Adding more devices will introduce undesired latency to the push request and in cases where there are hundreds or thousands of devices registered to an Alias, will prevent the notification from being delivered. If your use case requires something like this, you will need to use tags rather than Aliases.
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