How to convert from DispatchData to Data without copying the bytes

convert.swift

import Dispatch
import Foundation

var x = 7
let dd = withUnsafeBytes(of: &x, { DispatchData.init(bytes: $0) })
print(dd as? Data)                      // Case 1: nil
print(dd as? NSData)                    // Case 2: nil
print(dd as Any as? Data)               // Case 3: nil
print(dd as Any as? NSData)             // Case 4: .some
print(dd as Any as? NSData as Data?)    // Case 5: .some

let d = dd as Any as! NSData as Data
print(dd.withUnsafeBytes(body: { Int(bitPattern: $0) }) == d.withUnsafeBytes({ Int(bitPattern: $0) }))
// true

UPDATE! It turns out this is the most efficient way to convert a DispatchData to a Data, both in source code size and in memory and CPU time:

let d = dd as AnyObject as! Data

That did the trick!

let decompressedData = try (data as NSData).decompressed(using: compressionAlgorithm)
let payload = Data(compressedData)

Compiles fine, but crashes when it tries to access compressedData. But if cast it - following Mayoff's recommendation - we are in business.

guard let decompressedData = try (data as NSData).decompressed(using: compressionAlgorithm) as AnyObject as? Data else { }
let output = try JSONDecoder().decode(outputDataType, from: decompressedData)