We are creating an iOS SDK which will be used by multiple apps, we want to capture users with their unique device id. So if a user is using multiple apps on his device where our SDK is used we want to track that.
Can we use IDFA for that instead of creating a new uuid in each partner app? Also, we are not serving any adds or planning to serve in the near future.
No, that is not a valid use of the IDFA. This is covered in your Developer Program License Agreement:
3.3.12 You and Your Applications (and any third party with whom You have contracted to serve advertising) may use the Advertising Identifier, and any information obtained through the use of the Advertising Identifier, only for the purpose of serving advertising.
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In addition, You may request to use the Ad Network APIs to track application advertising conversion events. If You are granted permission to use the Ad Network APIs, You agree not to use such APIs, or any information obtained through the use of the Ad Network APIs, for any purpose other than verifying ad validation information as part of an advertising conversion event.
If you were to use the IDFA then there would be a risk of rejection for any apps using your SDK.