Swift 5 version syntax correction for https://stackoverflow.com/a/63682544

extractSubchunks.swift

func extractSubchunks(data:Data) -> RiffFile? {
    var data = data
    var chunks = [SubChunk]()
    let position = data.subdata(in: 8..<12)
    let filelengthBytes = data.subdata(in: 4..<8).map { UInt32($0) }
    let filelength: UInt32 = filelengthBytes[0] << 24 + filelengthBytes[1] << 16 + filelengthBytes[2] << 8 + filelengthBytes[3]
    let wave = String(bytes: position, encoding: .utf8) ?? "NoName"
    guard wave == "WAVE" else {
        print("File is \(wave) not WAVE")
        return nil
    }
    data.removeSubrange(0..<12)
    print("Found chunks")
    while data.count != 0{
        let position = data.subdata(in: 0..<4)
        let lengthBytes = data.subdata(in: 4..<8).map { UInt32($0) }
        let length: UInt32 = lengthBytes[0] << 24 + lengthBytes[1] << 16 + lengthBytes[2] << 8 + lengthBytes[3]
        guard let current = String(bytes: position, encoding: .utf8) else{
            return nil
        }
        data.removeSubrange(0..<8)
        let chunkData = data.subdata(in: 0..<Int(length))
        data.removeSubrange(0..<Int(length))
        let subchunk = SubChunk(name: current, size: Int(length), data: chunkData)
        chunks.append(subchunk)
        print(subchunk.debugDescription)
    }
    let riff = RiffFile(size: Int(filelength), subChunks: chunks)
    return riff
}