A value that indicates how much of the file has been downloaded.
- iOS 6.0+
- macOS 10.8+
- Mac Catalyst 13.0+
- tvOS 9.0+
The value of this property is a floating point number between
1, inclusive, where
0 means no data has been download and
1 means all the data has been downloaded. Typically, your app uses the value of this property to update a user interface element, such as a progress bar, that displays how much of the file has been downloaded.
Do not use the value of this property to determine whether the download has completed. Instead, use the