我想将“ abc”之类的字符串转换为MD5哈希。我想在iOS和Swift中做到这一点。我尝试使用以下解决方案，但它们对我不起作用：

在Swift框架中导入CommonCrypto

如何以快速的语言使用CC_MD5方法。

http://iosdeveloperzone.com/2014/10/03/using-commoncrypto-in-swift/

更清楚地说，我想在Swift中实现类似于此PHP代码输出的输出：

$str = "Hello";

echo md5($str);

输出：8b1a9953c4611296a827abf8c47804d7

分两个步骤：
1.从字符串创建md5数据
2.将md5数据隐蔽为十六进制字符串

Swift 2.0：

func md5(string string: String) -> String {
    var digest = [UInt8](count: Int(CC_MD5_DIGEST_LENGTH), repeatedValue: 0)
    if let data = string.dataUsingEncoding(NSUTF8StringEncoding) {
        CC_MD5(data.bytes, CC_LONG(data.length), &digest)
    }

    var digestHex = ""
    for index in 0..<Int(CC_MD5_DIGEST_LENGTH) {
        digestHex += String(format: "%02x", digest[index])
    }

    return digestHex
}

//Test:
let digest = md5(string:"Hello")
print("digest: \(digest)")

输出：

摘要：8b1a9953c4611296a827abf8c47804d7

Swift 3.0：

func MD5(string: String) -> Data {
    let messageData = string.data(using:.utf8)!
    var digestData = Data(count: Int(CC_MD5_DIGEST_LENGTH))

    _ = digestData.withUnsafeMutableBytes {digestBytes in
        messageData.withUnsafeBytes {messageBytes in
            CC_MD5(messageBytes, CC_LONG(messageData.count), digestBytes)
        }
    }

    return digestData
}

//Test:
let md5Data = MD5(string:"Hello")

let md5Hex =  md5Data.map { String(format: "%02hhx", $0) }.joined()
print("md5Hex: \(md5Hex)")

let md5Base64 = md5Data.base64EncodedString()
print("md5Base64: \(md5Base64)")

输出：

md5Hex：8b1a9953c4611296a827abf8c47804d7
md5Base64：ixqZU8RhEpaoJ6v4xHgE1w ==

Swift 5.0：

import Foundation
import var CommonCrypto.CC_MD5_DIGEST_LENGTH
import func CommonCrypto.CC_MD5
import typealias CommonCrypto.CC_LONG

func MD5(string: String) -> Data {
        let length = Int(CC_MD5_DIGEST_LENGTH)
        let messageData = string.data(using:.utf8)!
        var digestData = Data(count: length)

        _ = digestData.withUnsafeMutableBytes { digestBytes -> UInt8 in
            messageData.withUnsafeBytes { messageBytes -> UInt8 in
                if let messageBytesBaseAddress = messageBytes.baseAddress, let digestBytesBlindMemory = digestBytes.bindMemory(to: UInt8.self).baseAddress {
                    let messageLength = CC_LONG(messageData.count)
                    CC_MD5(messageBytesBaseAddress, messageLength, digestBytesBlindMemory)
                }
                return 0
            }
        }
        return digestData
    }

//Test:
let md5Data = MD5(string:"Hello")

let md5Hex =  md5Data.map { String(format: "%02hhx", $0) }.joined()
print("md5Hex: \(md5Hex)")

let md5Base64 = md5Data.base64EncodedString()
print("md5Base64: \(md5Base64)")

输出：

md5Hex：8b1a9953c4611296a827abf8c47804d7
md5Base64：ixqZU8RhEpaoJ6v4xHgE1w ==

注意：
#import <CommonCrypto/CommonCrypto.h>必须添加到Bridging-Header文件中

有关如何创建Bridging-Header的信息，请参见SO答案。

通常，不应将MD​​5用于新工作，SHA256是当前的最佳实践。

不推荐使用的文档部分中的示例：

MD2，MD4，MD5，SHA1，SHA224，SHA256，SHA384，SHA512（Swift 3+）

这些函数将使用八种密码哈希算法之一来哈希String或Data输入。

名称参数指定的散列函数的字符串名
支持的功能是MD2，MD4，MD5，SHA1，SHA224，SHA256，SHA384和SHA512一个这个例子需要公共的密码
是需要有一个桥接头项目：
#import <CommonCrypto/CommonCrypto.h>
添加安全.framework到项目。

此函数采用哈希名称和要哈希的String并返回一个Data：

name：作为字符串的哈希函数的名称  
string：要散列的字符串  
返回：哈希结果为Data  

func hash(name:String, string:String) -> Data? {
    let data = string.data(using:.utf8)!
    return hash(name:name, data:data)
}

例子：

let clearString = "clearData0123456"
let clearData   = clearString.data(using:.utf8)!
print("clearString: \(clearString)")
print("clearData: \(clearData as NSData)")

let hashSHA256 = hash(name:"SHA256", string:clearString)
print("hashSHA256: \(hashSHA256! as NSData)")

let hashMD5 = hash(name:"MD5", data:clearData)
print("hashMD5: \(hashMD5! as NSData)")

输出：

clearString: clearData0123456
clearData: <636c6561 72446174 61303132 33343536>

hashSHA256: <aabc766b 6b357564 e41f4f91 2d494bcc bfa16924 b574abbd ba9e3e9d a0c8920a>
hashMD5: <4df665f7 b94aea69 695b0e7b baf9e9d6>

在阅读完此处的其他答案之后（并且还需要支持其他哈希类型），我编写了一个String扩展，可以处理多种哈希类型和输出类型。

注意：CommonCrypto包含在Xcode 10中，因此，import CommonCrypto如果您安装了最新的Xcode版本，则无需弄乱桥接头就可以了...否则，桥接头是必需的。

更新：Swift 4和5都使用下面相同的String + Crypto.swift文件。

Swift 5有一个单独的Data + Crypto.swift文件（请参见下文），作为“ withUnsafeMutableBytes”和“ withUnsafeBytes”的api在Swift 4和5之间进行了更改。

String + Crypto.swift-（适用于Swift 4和5）

import Foundation
import CommonCrypto

// Defines types of hash string outputs available
public enum HashOutputType {
    // standard hex string output
    case hex
    // base 64 encoded string output
    case base64
}

// Defines types of hash algorithms available
public enum HashType {
    case md5
    case sha1
    case sha224
    case sha256
    case sha384
    case sha512

    var length: Int32 {
        switch self {
        case .md5: return CC_MD5_DIGEST_LENGTH
        case .sha1: return CC_SHA1_DIGEST_LENGTH
        case .sha224: return CC_SHA224_DIGEST_LENGTH
        case .sha256: return CC_SHA256_DIGEST_LENGTH
        case .sha384: return CC_SHA384_DIGEST_LENGTH
        case .sha512: return CC_SHA512_DIGEST_LENGTH
        }
    }
}

public extension String {

    /// Hashing algorithm for hashing a string instance.
    ///
    /// - Parameters:
    ///   - type: The type of hash to use.
    ///   - output: The type of output desired, defaults to .hex.
    /// - Returns: The requested hash output or nil if failure.
    public func hashed(_ type: HashType, output: HashOutputType = .hex) -> String? {

        // convert string to utf8 encoded data
        guard let message = data(using: .utf8) else { return nil }
        return message.hashed(type, output: output)
    } 
}

SWIFT 5-数据+加密.swift

import Foundation
import CommonCrypto

extension Data {

    /// Hashing algorithm that prepends an RSA2048ASN1Header to the beginning of the data being hashed.
    ///
    /// - Parameters:
    ///   - type: The type of hash algorithm to use for the hashing operation.
    ///   - output: The type of output string desired.
    /// - Returns: A hash string using the specified hashing algorithm, or nil.
    public func hashWithRSA2048Asn1Header(_ type: HashType, output: HashOutputType = .hex) -> String? {

        let rsa2048Asn1Header:[UInt8] = [
            0x30, 0x82, 0x01, 0x22, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86,
            0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00, 0x03, 0x82, 0x01, 0x0f, 0x00
        ]

        var headerData = Data(rsa2048Asn1Header)
        headerData.append(self)

        return hashed(type, output: output)
    }

    /// Hashing algorithm for hashing a Data instance.
    ///
    /// - Parameters:
    ///   - type: The type of hash to use.
    ///   - output: The type of hash output desired, defaults to .hex.
    ///   - Returns: The requested hash output or nil if failure.
    public func hashed(_ type: HashType, output: HashOutputType = .hex) -> String? {

        // setup data variable to hold hashed value
        var digest = Data(count: Int(type.length))

        _ = digest.withUnsafeMutableBytes{ digestBytes -> UInt8 in
            self.withUnsafeBytes { messageBytes -> UInt8 in
                if let mb = messageBytes.baseAddress, let db = digestBytes.bindMemory(to: UInt8.self).baseAddress {
                    let length = CC_LONG(self.count)
                    switch type {
                    case .md5: CC_MD5(mb, length, db)
                    case .sha1: CC_SHA1(mb, length, db)
                    case .sha224: CC_SHA224(mb, length, db)
                    case .sha256: CC_SHA256(mb, length, db)
                    case .sha384: CC_SHA384(mb, length, db)
                    case .sha512: CC_SHA512(mb, length, db)
                    }
                }
                return 0
            }
        }

        // return the value based on the specified output type.
        switch output {
        case .hex: return digest.map { String(format: "%02hhx", $0) }.joined()
        case .base64: return digest.base64EncodedString()
        }
    }
}

SWIFT 4-数据+加密.swift

import Foundation
import CommonCrypto 

extension Data {

    /// Hashing algorithm that prepends an RSA2048ASN1Header to the beginning of the data being hashed.
    ///
    /// - Parameters:
    ///   - type: The type of hash algorithm to use for the hashing operation.
    ///   - output: The type of output string desired.
    /// - Returns: A hash string using the specified hashing algorithm, or nil.
    public func hashWithRSA2048Asn1Header(_ type: HashType, output: HashOutputType = .hex) -> String? {

        let rsa2048Asn1Header:[UInt8] = [
            0x30, 0x82, 0x01, 0x22, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86,
            0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00, 0x03, 0x82, 0x01, 0x0f, 0x00
        ]

        var headerData = Data(bytes: rsa2048Asn1Header)
        headerData.append(self)

        return hashed(type, output: output)
    }

    /// Hashing algorithm for hashing a Data instance.
    ///
    /// - Parameters:
    ///   - type: The type of hash to use.
    ///   - output: The type of hash output desired, defaults to .hex.
    ///   - Returns: The requested hash output or nil if failure.
    public func hashed(_ type: HashType, output: HashOutputType = .hex) -> String? {

        // setup data variable to hold hashed value
        var digest = Data(count: Int(type.length))

        // generate hash using specified hash type
        _ = digest.withUnsafeMutableBytes { (digestBytes: UnsafeMutablePointer<UInt8>) in
            self.withUnsafeBytes { (messageBytes: UnsafePointer<UInt8>) in
                let length = CC_LONG(self.count)
                switch type {
                case .md5: CC_MD5(messageBytes, length, digestBytes)
                case .sha1: CC_SHA1(messageBytes, length, digestBytes)
                case .sha224: CC_SHA224(messageBytes, length, digestBytes)
                case .sha256: CC_SHA256(messageBytes, length, digestBytes)
                case .sha384: CC_SHA384(messageBytes, length, digestBytes)
                case .sha512: CC_SHA512(messageBytes, length, digestBytes)
                }
            }
        }

        // return the value based on the specified output type.
        switch output {
        case .hex: return digest.map { String(format: "%02hhx", $0) }.joined()
        case .base64: return digest.base64EncodedString()
        }
    }
}

编辑：由于哈希实际上发生在数据上，所以我将哈希算法拆分为数据扩展。这也允许将相同的算法用于SSL证书固定哈希操作。

这是一个简短示例，说明如何将其用于SSL固定操作：

// Certificate pinning - get certificate as data
let data: Data = SecCertificateCopyData(serverCertificate) as Data

// compare hash of server certificate with local (expected) hash value
guard let serverHash = data.hashWithRSA2048Asn1Header(.sha256, output: .base64), serverHash == storedHash else {
    print("SSL PINNING: Server certificate hash does not match specified hash value.")
    return false
}

回到原始答案

我使用以下方法测试了哈希算法：

let value = "This is my string"

if let md5 = value.hashed(.md5) {
    print("md5: \(md5)")
}
if let sha1 = value.hashed(.sha1) {
    print("sha1: \(sha1)")
}
if let sha224 = value.hashed(.sha224) {
    print("sha224: \(sha224)")
}
if let sha256 = value.hashed(.sha256) {
    print("sha256: \(sha256)")
}
if let sha384 = value.hashed(.sha384) {
    print("sha384: \(sha384)")
}
if let sha512 = value.hashed(.sha512) {
    print("sha512: \(sha512)")
}

这是打印结果：

md5: c2a9ce57e8df081b4baad80d81868bbb
sha1: 37fb219bf98bee51d2fdc3ba6d866c97f06c8223
sha224: f88e2f20aa89fb4dffb6bdc62d7bd75e1ba02574fae4a437c3bf49c7
sha256: 9da6c02379110815278b615f015f0b254fd3d5a691c9d8abf8141655982c046b
sha384: d9d7fc8aefe7f8f0a969b132a59070836397147338e454acc6e65ca616099d03a61fcf9cc8c4d45a2623145ebd398450
sha512: 349cc35836ba85915ace9d7f895b712fe018452bb4b20ff257257e12adeb1e83ad780c6568a12d03f5b2cb1e3da23b8b7ced9012a188ef3855e0a8f3db211883

从iOS 13开始， Apple已添加CryptoKit框架，因此您不再需要导入CommonCrypto或处理其C API：

import Foundation
import CryptoKit

func MD5(string: String) -> String {
    let digest = Insecure.MD5.hash(data: string.data(using: .utf8) ?? Data())

    return digest.map {
        String(format: "%02hhx", $0)
    }.joined()
}

SWIFT 3版本md5 function：

func md5(_ string: String) -> String {

    let context = UnsafeMutablePointer<CC_MD5_CTX>.allocate(capacity: 1)
    var digest = Array<UInt8>(repeating:0, count:Int(CC_MD5_DIGEST_LENGTH))
    CC_MD5_Init(context)
    CC_MD5_Update(context, string, CC_LONG(string.lengthOfBytes(using: String.Encoding.utf8)))
    CC_MD5_Final(&digest, context)
    context.deallocate(capacity: 1)
    var hexString = ""
    for byte in digest {
        hexString += String(format:"%02x", byte)
    }

    return hexString
}

来自http://iosdeveloperzone.com的原始链接

Swift 4。*，Xcode 10更新：

在Xcode 10中，您不必再使用Bridging-Header，您可以直接使用导入

import CommonCrypto

然后编写类似下面的方法：

func MD5(_ string: String) -> String? {
        let length = Int(CC_MD5_DIGEST_LENGTH)
        var digest = [UInt8](repeating: 0, count: length)

        if let d = string.data(using: String.Encoding.utf8) {
            _ = d.withUnsafeBytes { (body: UnsafePointer<UInt8>) in
                CC_MD5(body, CC_LONG(d.count), &digest)
            }
        }

        return (0..<length).reduce("") {
            $0 + String(format: "%02x", digest[$1])
        }
    }

用法：

MD5("This is my string")

输出：

c2a9ce57e8df081b4baad80d81868bbb

我发布了一个不依赖CommonCrypto或其他任何东西的纯Swift实现。它已获得MIT许可。

该代码包含一个单独的swift文件，您可以将其放入项目中。如果愿意，还可以将包含的Xcode项目与框架和单元测试目标一起使用。

使用简单：

let input = "The quick brown fox jumps over the lazy dog"
let digest = input.utf8.md5
print("md5: \(digest)")

印刷品： md5: 9e107d9d372bb6826bd81d3542a419d6

swift文件包含文档和更多示例。

这里只有两个注释：

为此，使用Crypto会产生过多开销。

该接受的答案是完美的！不过，我只是想分享一个使用Swift 2.2的Swift ier代码方法。

请记住，您仍然必须#import <CommonCrypto/CommonCrypto.h>在Bridging-Header文件中

struct MD5Digester {
    // return MD5 digest of string provided
    static func digest(string: String) -> String? {

        guard let data = string.dataUsingEncoding(NSUTF8StringEncoding) else { return nil }

        var digest = [UInt8](count: Int(CC_MD5_DIGEST_LENGTH), repeatedValue: 0)

        CC_MD5(data.bytes, CC_LONG(data.length), &digest)

        return (0..<Int(CC_MD5_DIGEST_LENGTH)).reduce("") { $0 + String(format: "%02x", digest[$1]) }
    }
}

Swift 5答案作为String扩展（基于Invictus Cody的出色答案）：

import CommonCrypto

extension String {
    var md5Value: String {
        let length = Int(CC_MD5_DIGEST_LENGTH)
        var digest = [UInt8](repeating: 0, count: length)

        if let d = self.data(using: .utf8) {
            _ = d.withUnsafeBytes { body -> String in
                CC_MD5(body.baseAddress, CC_LONG(d.count), &digest)

                return ""
            }
        }

        return (0 ..< length).reduce("") {
            $0 + String(format: "%02x", digest[$1])
        }
    }
}

用法：

print("test".md5Value) /*098f6bcd4621d373cade4e832627b4f6*/

这是基于zaph答案的扩展

extension String{
    var MD5:String {
        get{
            let messageData = self.data(using:.utf8)!
            var digestData = Data(count: Int(CC_MD5_DIGEST_LENGTH))

            _ = digestData.withUnsafeMutableBytes {digestBytes in
                messageData.withUnsafeBytes {messageBytes in
                    CC_MD5(messageBytes, CC_LONG(messageData.count), digestBytes)
                }
            }

            return digestData.map { String(format: "%02hhx", $0) }.joined()
        }
    }
}

与swift 3.0完全兼容#import <CommonCrypto/CommonCrypto.h>。您仍然必须在Bridging-Header文件中

在快速编程中，最好使用字符串函数，因此使用起来很容易。在这里，我使用上述给定的解决方案之一进行String扩展。谢谢@wajih

import Foundation
import CommonCrypto

extension String {

func md5() -> String {

    let context = UnsafeMutablePointer<CC_MD5_CTX>.allocate(capacity: 1)
    var digest = Array<UInt8>(repeating:0, count:Int(CC_MD5_DIGEST_LENGTH))
    CC_MD5_Init(context)
    CC_MD5_Update(context, self, CC_LONG(self.lengthOfBytes(using: String.Encoding.utf8)))
    CC_MD5_Final(&digest, context)
    context.deallocate()
    var hexString = ""
    for byte in digest {
        hexString += String(format:"%02x", byte)
    }

    return hexString
}
}

用法

let md5String = "abc".md5()

我用迦太基和Cyrpto来做到这一点。

1. 如果尚未安装迦太基，请安装

2. 将Crypto安装到您的项目中

3. 执行“升级更新”

4. 如果您是从命令行运行的，请在swift文件的框架中添加

   #!/usr/bin/env xcrun swift -F Carthage/Build/Mac

5. 将import Crypto添加到您的swift文件。

6. 那么就可以了！

   print( "convert this".MD5 )

MD5是一种哈希算法，无需为此使用笨重的CommonCrypto库（并且被Apple评论拒绝），只需使用任何md5哈希库即可。

我使用的一个这样的库是SwiftHash，它是MD5的纯Swift实现（基于http://pajhome.org.uk/crypt/md5/md5.html）

基于Cody的解决方案，我有一个想法，我们应该弄清楚MD5的结果是什么，因为我们可以将结果用作十六进制字符串或Base64字符串。

func md5(_ string: String) -> [UInt8] {
    let length = Int(CC_MD5_DIGEST_LENGTH)
    var digest = [UInt8](repeating: 0, count: length)

    if let d = string.data(using: String.Encoding.utf8) {
        _ = d.withUnsafeBytes { (body: UnsafePointer<UInt8>) in
            CC_MD5(body, CC_LONG(d.count), &digest)
        }
    }
    return digest
}

上面的函数实际上返回一个[UInt8]，根据此结果，我们可以获取任何形式的字符串，例如hex，base64。

如果需要十六进制字符串作为最终结果（如问题所示），我们可以继续使用Cody解决方案的其余部分

extension String {
    var md5Hex: String {
        let length = Int(CC_MD5_DIGEST_LENGTH)
        return (0..<length).reduce("") {
            $0 + String(format: "%02x", digest[$1])
        }
    }
}

如果想要使用Base64字符串作为最终结果

extension String {
    var md5Base64: String {
        let md5edData = Data(bytes: md5(self))
        return md5edData.base64EncodedString()
    }
}

使用适当的内存管理并且方法内部没有类的Swift 5答案String：

typealias CBridgeCryptoMethodType = (UnsafeRawPointer?,
                                 UInt32,
                                 UnsafeMutablePointer<UInt8>?)
-> UnsafeMutablePointer<UInt8>?

private enum HashType {

    // MARK: - Cases

    case md5
    case sha1
    case sha224
    case sha256
    case sha384
    case sha512
}

extension Data {
    var hexString: String {
        let localHexString = reduce("", { previous, current in
            return previous + String(format: "%02X", current)
        })
        return localHexString
    }
    var md5: Data {
        return hashed(for: .md5)
    }
    var sha1: Data {
        return hashed(for: .sha1)
    }
    var sha224: Data {
        return hashed(for: .sha224)
    }
    var sha256: Data {
        return hashed(for: .sha256)
    }
    var sha384: Data {
        return hashed(for: .sha384)
    }
    var sha512: Data {
        return hashed(for: .sha512)
    }

    private func hashed(for hashType: HashType) -> Data {
        return withUnsafeBytes { (rawBytesPointer: UnsafeRawBufferPointer) -> Data in
            guard let bytes = rawBytesPointer.baseAddress?.assumingMemoryBound(to: Float.self) else {
                return Data()
            }
            let hashMethod: CBridgeCryptoMethodType
            let digestLength: Int
            switch hashType {
            case .md5:
                hashMethod = CC_MD5
                digestLength = Int(CC_MD5_DIGEST_LENGTH)
            case .sha1:
                hashMethod = CC_SHA1
                digestLength = Int(CC_SHA1_DIGEST_LENGTH)
            case .sha224:
                hashMethod = CC_SHA224
                digestLength = Int(CC_SHA224_DIGEST_LENGTH)
            case .sha256:
                hashMethod = CC_SHA256
                digestLength = Int(CC_SHA256_DIGEST_LENGTH)
            case .sha384:
                hashMethod = CC_SHA384
                digestLength = Int(CC_SHA384_DIGEST_LENGTH)
            case .sha512:
                hashMethod = CC_SHA512
                digestLength = Int(CC_SHA512_DIGEST_LENGTH)
            }
            let result = UnsafeMutablePointer<UInt8>.allocate(capacity: digestLength)
            _ = hashMethod(bytes, CC_LONG(count), result)
            let md5Data = Data(bytes: result, count: digestLength)
            result.deallocate()
            return md5Data
        }
    }
}

例

let str = "The most secure string ever"
print("md5", str.data(using: .utf8)?.md5.hexString)
print("sha1", str.data(using: .utf8)?.sha1.hexString)
print("sha224", str.data(using: .utf8)?.sha224.hexString)
print("sha256", str.data(using: .utf8)?.sha256.hexString)
print("sha384", str.data(using: .utf8)?.sha384.hexString)
print("sha512", str.data(using: .utf8)?.sha512.hexString)

结果：

md5可选（“ 671C121427F12FBBA66CEE71C44CB62C”）

sha1可选（“ A6A40B223AE634CFC8C191DDE024BF0ACA56D7FA”）

sha224可选（“ 334370E82F2F5ECF5B2CA0910C6176D94CBA12FD6F518A7AB8D12ADE”）

sha256可选（“ 8CF5ED971D6EE2579B1BDEFD4921415AC03DA45B49B89665B3DF197287EFC89D”）

sha384可选（“ 04BB3551CBD60035BA7E0BAA141AEACE1EF5E17317A8FD108DA12A7A8E98C245E14F92CC1A241C732209EAC9D600602E”）

sha512可选（“ 1D595EAFEB2162672830885D336F75FD481548AC463BE16A8D98DB33637213F1AEB36FA4977B9C23A82A4FAB8A70C06AFC64C610D3CB1FE77A609DC8EE86AA68”

我发现此库似乎运行良好。

https://github.com/onmyway133/SwiftHash

MD5("string")

我的两分钱（如果您需要快速使用md5来存储Data / NSData，例如您下载或读取了磁盘或netwkork的二进制文件）

（从“作为字符串扩展的Swift 5答案（基于Invictus Cody的出色答案”中得出的结论是无耻的））：

extension Data {
    var md5Value: String {
        let length = Int(CC_MD5_DIGEST_LENGTH)
        var digest = [UInt8](repeating: 0, count: length)

        _ = self.withUnsafeBytes { body -> String in
            CC_MD5(body.baseAddress, CC_LONG(self.count), &digest)
            return ""
        }


        return (0 ..< length).reduce("") {
            $0 + String(format: "%02x", digest[$1])
        }
    }
} 

测试：

print("test".data.md5Value) /*098f6bcd4621d373cade4e832627b4f6*/