Brotli compression is documented as available in iOS 13+. But my experience is that if I try to use Brotli compression prior to iOS 16 that my app will suffer a dload failure trying to dynamically link against the Compression library. I have solved this, sort of, by weak linking against libCompression, and check that the IOS version >= 16 prior to using .brotli Here's how I'm using brotli: let outputFilter = try OutputFilter(.compress, using: .brotli) { (data: Data?) -> Void in if let data { compressedData.append(data) } } (The above will cause a dload error on iOS 15) Questions: Is this a known issue? Is there any better way to test weather .brotli is available than checking the iOS version? I have somewhat anecdotal evidence that the OS version may no be the full story.