---
title: adImpressionIdentifier
framework: storekit
role: symbol
role_heading: Instance Property
path: storekit/skadimpression/adimpressionidentifier
---

# adImpressionIdentifier

A random value to use for added security.

## Declaration

```swift
var adImpressionIdentifier: String { get set }
```

## Mentioned in

Generating the signature to validate view-through ads

## Discussion

Discussion Ad networks set the value of this property to a random value (nonce) at the time of the ad impression. important: When you generate signature, which is the signature value, you must sign the adImpressionIdentifier as an all-lowercase UUID string representation.

## 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)
- [sourceIdentifier](storekit/skadimpression/sourceidentifier.md)
- [adCampaignIdentifier](storekit/skadimpression/adcampaignidentifier.md)
- [advertisedAppStoreItemIdentifier](storekit/skadimpression/advertisedappstoreitemidentifier.md)
- [sourceAppStoreItemIdentifier](storekit/skadimpression/sourceappstoreitemidentifier.md)
- [timestamp](storekit/skadimpression/timestamp.md)