Swift 3 making sha1, sha256 and md5 functions

Question

In Swift 2, I used the following code to extend string variables and to be able to make sha1, sha256, and md5.

After moving to swift 3, the code is not working any more! I tried to convert it but run into continuous errors.

Any idea how can I solve this?

extension NSData {
    func hexString() -> String {
        var string = String()
        for i in UnsafeBufferPointer<UInt8>(start: UnsafeMutablePointer<UInt8>(bytes), count: length) {
            string += Int(i).hexString()
        }
        return string
    }

    func MD5() -> NSData {
        let result = NSMutableData(length: Int(CC_MD5_DIGEST_LENGTH))!
        CC_MD5(bytes, CC_LONG(length), UnsafeMutablePointer<UInt8>(result.mutableBytes))
        return NSData(data: result)
    }

    func SHA1() -> NSData {
        let result = NSMutableData(length: Int(CC_SHA1_DIGEST_LENGTH))!
        CC_SHA1(bytes, CC_LONG(length), UnsafeMutablePointer<UInt8>(result.mutableBytes))
        return NSData(data: result)
    }

    func SHA256() -> NSData {
        let result = NSMutableData(length: Int(CC_SHA256_DIGEST_LENGTH))
        CC_SHA256(bytes, CC_LONG(length), UnsafeMutablePointer(result!.mutableBytes))
        return NSData(data: result!)
    }
}

extension String {
    func hexString() -> String {
        return (self as NSString).dataUsingEncoding(NSUTF8StringEncoding)!.hexString()
    }

    func MD5() -> String {
        return (self as NSString).dataUsingEncoding(NSUTF8StringEncoding)!.MD5().hexString()
    }

    func SHA1() -> String {
        return (self as NSString).dataUsingEncoding(NSUTF8StringEncoding)!.SHA1().hexString()
    }

    func SHA256() -> String {
        return (self as NSString).dataUsingEncoding(NSUTF8StringEncoding)!.SHA256().hexString()
    }

}

Answer 1

You'd better use Swift Data in Swift 3.

Data

And when working with Data, you need to use withUnsafeBytes(_:) or withUnsafeMutableBytes(_:), where you were using bytes or mutableBytes respectively.

withUnsafeBytes(_:)

withUnsafeMutableBytes(_:)

extension Data {
    func hexString() -> String {
        let string = self.map{Int($0).hexString()}.joined()
        return string
    }

    func MD5() -> Data {
        var result = Data(count: Int(CC_MD5_DIGEST_LENGTH))
        _ = result.withUnsafeMutableBytes {resultPtr in
            self.withUnsafeBytes {(bytes: UnsafePointer<UInt8>) in
                CC_MD5(bytes, CC_LONG(count), resultPtr)
            }
        }
        return result
    }

    /*
    ... nearly the same for `SHA1` and `SHA256`.
     */
}

extension String {
    func hexString() -> String {
        return self.data(using: .utf8)!.hexString()
    }

    func MD5() -> String {
        return self.data(using: .utf8)!.MD5().hexString()
    }

    /*
    ... nearly the same for `SHA1` and `SHA256`.
     */
}

I prefer making computed properties than no-argument methods (for relatively light-tasks). You need to fix all parts using them, but you can write something like this:

extension Int {
    var hexString: String {
        return ...
    }
}
extension Data {
    var hexString: String {
        let string = self.map{Int($0).hexString}.joined()
        return string
    }

    var MD5: Data {
        var result = Data(count: Int(CC_MD5_DIGEST_LENGTH))
        _ = result.withUnsafeMutableBytes {resultPtr in
            self.withUnsafeBytes {(bytes: UnsafePointer<UInt8>) in
                CC_MD5(bytes, CC_LONG(count), resultPtr)
            }
        }
        return result
    }

    /*
    ... nearly the same for `SHA1` and `SHA256`.
     */
}

extension String {
    var hexString: String {
        return self.data(using: .utf8)!.hexString
    }

    var MD5: String {
        return self.data(using: .utf8)!.MD5.hexString
    }

    /*
    ... nearly the same for `SHA1` and `SHA256`.
     */
}

---

There may be a quicker fix for your code using NSData, but I recommend you to move to Data in Swift 3.