Playground Swift5

StreamTest.swift

import UIKit

extension OutputStream {
    func write(data: Data) -> Int {
        return data.withUnsafeBytes {
          write($0.bindMemory(to: UInt8.self).baseAddress!, maxLength: data.count)
        }
    }
    
    var data: Data? {
        guard let nsData = property(forKey: .dataWrittenToMemoryStreamKey) as? NSData else {
            return nil
        }
        return Data(referencing: nsData)
    }
}

extension InputStream {
  func read(data: inout Data) -> Int {
    let count = data.count
    return data.withUnsafeMutableBytes {
      read($0.bindMemory(to: UInt8.self).baseAddress!, maxLength: count)
    }
  }
}

func byteArray<T>(from value: T) -> [UInt8] where T: FixedWidthInteger {
    return withUnsafeBytes(of: value.bigEndian) { Array($0) }
}

extension Data {
    var uint32:UInt32 {
        return UInt32(bigEndian: self.withUnsafeBytes { bytes in
            bytes.load(as: UInt32.self)
        })
    }
}

struct Bone : Codable {
    var name: String
}

let stream = OutputStream(toMemory: ())
stream.open()

let b = Bone(name: "hoge")
let data = try! JSONEncoder().encode(b)
let bytes = Data(byteArray(from: Int32(data.count)))
stream.write(data: bytes)
stream.write(data: data)

let b2 = Bone(name: "fugafuga")
let data2 = try! JSONEncoder().encode(b2)
let bytes2 = Data(byteArray(from: Int32(data2.count)))
stream.write(data: bytes2)
stream.write(data: data2)

stream.close()

let inputBytes : Data = stream.data!
let input = InputStream(data: inputBytes)

input.open()
while(input.hasBytesAvailable){
    var d = Data(count: 4)
    input.read(data: &d)
    
    let len = d.uint32
    d = Data(count: Int(len))
    input.read(data: &d)
    
    let json = try! JSONDecoder().decode(Bone.self, from: d)
    print(json)
}