Creates a string from the given bytes in the UTF16 encoding.

string_decode_utf16_bytes.swift

extension String {

    /// Creates a string from the given bytes in the specified encoding.
    init<C>(decoding bytes: C, as sourceEncoding: UTF16.Type) where C : Collection, C.Element == UInt8, C.Index == Int {
        let codeUnits = stride(from: bytes.startIndex, to: bytes.endIndex, by: MemoryLayout<UTF16.CodeUnit>.stride).map { index -> UTF16.CodeUnit in
            UTF16.CodeUnit(bytes[index]) | (UTF16.CodeUnit(bytes[index.advanced(by: 1)]) &<< 8)
        }

        self.init(decoding: codeUnits, as: sourceEncoding)
    }

}

// let bytes: [UInt8] = [97, 0, 98, 0, 99, 0, 100, 0, 5, 1]
// let string = String(decoding: bytes, as: UTF16.self)
// string == "abcdą"

UTF16_to_bytes.swift

extension Array where Element == UInt16 {
    
    /// Little-Endian UTF16 bytes
    var bytes: [UInt8] {
        flatMap {
            [
                UInt8($0.littleEndian & 0xFF),
                UInt8(($0.littleEndian &>> 8) & 0xFF)
            ]
        }
    }
}

extension String.UTF16View {
    /// Little-Endian UTF16 bytes
    var bytes: [UInt8] {
        Array(self).bytes
    }
    
}