# PHAssetVideoProgressHandler The signature for a block that Photos calls while downloading asset data from iCloud. Used by the [`progressHandler`](/documentation/Photos/PHVideoRequestOptions/progressHandler) property. ``` typealias PHAssetVideoProgressHandler = (Double, (any Error)?, UnsafeMutablePointer, [AnyHashable : Any]?) -> Void ``` ## Discussion If you request a video asset whose data is not on the local device, and you have enabled downloading with the [`isNetworkAccessAllowed`](/documentation/Photos/PHVideoRequestOptions/isNetworkAccessAllowed) property, Photos calls your block periodically to report progress and allow canceling the download. > Note: > Because Photos calls this block in an arbitrary serial queue, it may not execute on the main thread. The block takes the following parameters: - progress: A floating-point value indicating the progress of the download. A value of `0.0` indicates the download has just started, and a value of `1.0` indicates the download is complete. - error: An `NSError` object describing an error that occurred when attempting to download the video, or `nil` if no errors have occurred. - stop: A pointer to a Boolean value. To cancel the download, set `*stop` to `true` inside the block. - info: A dictionary providing additional information about the status of the video request. See Image Result Info Keys for possible keys and values. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)