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# annotation

A key indicating that the URL passed to your app contained custom annotation data from the source app.

```
static let annotation: UIApplication.LaunchOptionsKey
```

## Discussion

The presence of this key indicates that custom data was provided by the app that requested the opening of the URL. The value of this key is a property-list object containing the custom data. The same object is also passed to the annotation parameter of the  [`application(_:open:sourceApplication:annotation:)`](/documentation/UIKit/UIApplicationDelegate/application(_:open:sourceApplication:annotation:)) method. The contents of this property-list object are specific to the app that made the request.

---

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