Data

Data16Sequence.swift

import Foundation

struct Data16: Sequence, IteratorProtocol {
    let data8: Data
    init(_ data8: Data) {
        self.data8 = data8
        self.currentIndex = 0
    }

    var currentIndex: Int

    mutating func next() -> UInt16? {
        return data8.withUnsafeBytes { (utf16Pointer: UnsafePointer<UInt16>) -> (UInt16?) in 
            guard self.currentIndex < (self.data8.count) / 2
                else { return nil }

            defer { self.currentIndex += 1 }
            return utf16Pointer[self.currentIndex]
        }
    }
}

let str = "あ"
let data16 = Data16(str.data(using: .utf16)!)
for d in data16 {
    print("type(of: d) = \(type(of: d))")
    print(d)
}