---
title: sourceIdentifier
framework: storekit
role: symbol
role_heading: Instance Property
path: storekit/skadimpression/sourceidentifier
---

# sourceIdentifier

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

## Declaration

```swift
var sourceIdentifier: NSNumber { get set }
```

## Mentioned in

Generating the signature to validate view-through ads Identifying the parameters in install-validation postbacks SKAdNetwork 4 release notes

## Discussion

Discussion The sourceIdentifier key is available for ad impressions that use SKAdNetwork 4 and later. The sourceIdentifier, also known as the hierarchical source identifier, replaces and extends the campaign identifier value, adCampaignIdentifier. Ad networks and developers define the meaning of the hierarchical source identifier. This integer can have up to four digits. You can encode information about your advertisement in each set of digits; you may receive two, three, or all four digits of the sourceIdentifier in the first winning postback, depending on the ad impression’s postback data tier. For more information about the value you may get in the postback, see Receiving postbacks in multiple conversion windows. note: An install-validation postback represents this integer as a string in its source-identifier parameter. For more details about the parameters of an install-validation postback, see Identifying the parameters in install-validation postbacks.

## See Also

### Creating a signature

- [init(sourceAppStoreItemIdentifier:advertisedAppStoreItemIdentifier:adNetworkIdentifier:adCampaignIdentifier:adImpressionIdentifier:timestamp:signature:version:)](storekit/skadimpression/init(sourceappstoreitemidentifier:advertisedappstoreitemidentifier:adnetworkidentifier:adcampaignidentifier:adimpressionidentifier:timestamp:signature:version:).md)
- [version](storekit/skadimpression/version.md)
- [adNetworkIdentifier](storekit/skadimpression/adnetworkidentifier.md)
- [adCampaignIdentifier](storekit/skadimpression/adcampaignidentifier.md)
- [advertisedAppStoreItemIdentifier](storekit/skadimpression/advertisedappstoreitemidentifier.md)
- [adImpressionIdentifier](storekit/skadimpression/adimpressionidentifier.md)
- [sourceAppStoreItemIdentifier](storekit/skadimpression/sourceappstoreitemidentifier.md)
- [timestamp](storekit/skadimpression/timestamp.md)