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# PHAssetResourceProgressHandler

The signature for a block that Photos calls while downloading asset resource data from iCloud. Used by the [`progressHandler`](/documentation/Photos/PHAssetResourceRequestOptions/progressHandler) property.

```
typealias PHAssetResourceProgressHandler = (Double) -> Void
```

## Discussion

If you request an asset resource whose data is not on the local device, and you have enabled downloading with the [`isNetworkAccessAllowed`](/documentation/Photos/PHAssetResourceRequestOptions/isNetworkAccessAllowed) property, Photos calls your block periodically to report progress.

The block takes a single parameter:

- progress: A floating-point value indicating the progress of the download. A value of `0.0` indicates that the download has just started, and a value of `1.0` indicates the download is complete.

---

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