Swift helper to convert a string or a file to a md5sum

MD5.swift

class MD5{

    static func stringSum(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
    }

    static func fileSum(path: String) -> String {
        var digest = [UInt8](count: Int(CC_MD5_DIGEST_LENGTH), repeatedValue: 0)
        let handle: NSFileHandle? = NSFileHandle(forReadingAtPath: path)

        let md5 = UnsafeMutablePointer<CC_MD5_CTX>.alloc(1)
        CC_MD5_Init(md5)

        while (true) {
            let fileData = handle!.readDataOfLength(4096)
            CC_MD5_Update(md5, fileData.bytes, CC_LONG(fileData.length));
            if fileData.length == 0 {
                break
            }
        }

        CC_MD5_Final(&digest, md5)
        md5.dealloc(1)

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

        return digestHex
    }
}

When i was trying to use your function in my Custom Swift Framework, i get these errors. Would you like to tell me how to get ride of them.
Use of unresolved identifier 'CC_LONG'
Use of unresolved identifier 'CC_MD5_DIGEST_LENGTH'
Use of unresolved identifier 'CC_MD5'