---
title: PHAssetImageProgressHandler
framework: photos
role: symbol
role_heading: Type Alias
path: photos/phassetimageprogresshandler
---

# PHAssetImageProgressHandler

The signature for a block that Photos calls while downloading asset data from iCloud. Used by the progressHandler property.

## Declaration

```swift
typealias PHAssetImageProgressHandler = (Double, (any Error)?, UnsafeMutablePointer<ObjCBool>, [AnyHashable : Any]?) -> Void
```

## Discussion

Discussion If you request an image whose data is not on the local device, and you have enabled downloading with the isNetworkAccessAllowed property, Photos calls your block periodically to report progress and to allow you to cancel the download. note: Photos calls this block in an arbitrary serial queue. Dispatch to the main thread if your handler needs to update the user interface. The block takes the following parameters:

## See Also

### Fetching Image Data from iCloud

- [isNetworkAccessAllowed](photos/phimagerequestoptions/isnetworkaccessallowed.md)
- [progressHandler](photos/phimagerequestoptions/progresshandler.md)