<!--
{
  "availability" : [
    "iOS: 17.4.0 -",
    "iPadOS: 17.4.0 -",
    "macCatalyst: -"
  ],
  "documentType" : "symbol",
  "framework" : "AdAttributionKit",
  "identifier" : "/documentation/AdAttributionKit/AppImpression/sourceID",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Property",
  "symbol" : {
    "kind" : "Instance Property",
    "modules" : [
      "AdAttributionKit"
    ],
    "preciseIdentifier" : "s:16AdAttributionKit13AppImpressionV8sourceIDSivp"
  },
  "title" : "sourceID"
}
-->

# sourceID

A four-digit integer that ad networks define to represent the ad campaign.

```
var sourceID: Int { get }
```

## Discussion

The `sourceID` is also known as the *hierarchical source identifier*. Ad networks and developers define its meaning.
This integer can have up to four digits. You might receive two, three, or all four digits of the `sourceID` in the first winning
postback, based on the data tier of the postback. You can use the different digits of the source identifier to represent different
aspects of your ad, such as campaign information, placement, locale, and so on. For more information about the
values you might get in the postback, see [Identifying the parameters in a postback](/documentation/AdAttributionKit/identifying-the-parameters-in-a-postback).

> Note: A postback report represents this integer as a string in the `source-identifier` parameter in the payload of the
> JSON Web Signature (JWS). For more details about the parameters of a postback, see
> <doc://com.apple.AdAttributionKit/documentation/AdAttributionKit/identifying-the-parameters-in-a-postback>.

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)