Swift3でStringをMD5に変換する

stringToMD5.swift

/* （メモ）
 * Bridging-Header.hに
 * #import <CommonCrypto/CommonDigest.h>
 * を書いておく。
 */
func md5(_ string: String) -> String {
    var md5String = ""
    let digestLength = Int(CC_MD5_DIGEST_LENGTH)
    let md5Buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: digestLength)

    if let data = string.data(using: .utf8) {
        data.withUnsafeBytes({ (bytes: UnsafePointer<CChar>) -> Void in
            CC_MD5(bytes, CC_LONG(data.count), md5Buffer)
            md5String = (0..<digestLength).reduce("") { $0 + String(format:"%02x", md5Buffer[$1]) }
        })
    }

    return md5String
}