Apple has released the ninth beta of watchOS 6 to the developers

Networking
New Features
To enhance security, URLSession no longer sniffs the MIME type when the server sends Content-Type: application/octet-stream. (7820658)

NSURLRequest.CachePolicy.reloadRevalidatingCacheData and NSURLRequest.CachePolicy.reloadIgnoringLocalAndRemoteCacheData APIs are now available. (49660334)

URLSessionWebSocketTask and URLSessionStreamTask are now available for use in watchOS apps. (49779789)

Known Issues
The urlSession(_:taskIsWaitingForConnectivity:) delegate callback might not function as expected. (54309264)

Release notes
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