The expected length of the response’s content.
- iOS 2.0+
- macOS 10.2+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
This property’s value is
NSURLResponse if the length can’t be determined.
Some protocol implementations report the content length as part of the response, but not all protocols guarantee to deliver that amount of data. Your app should be prepared to deal with more or less data.