diff --git a/Polyglot/Polyglot.swift b/Polyglot/Polyglot.swift
index 159f1a1..828d3c5 100644
--- a/Polyglot/Polyglot.swift
+++ b/Polyglot/Polyglot.swift
@@ -117,15 +117,15 @@ public enum Language: String {
 /**
     Responsible for translating text.
 */
-public class Polyglot {
+open class Polyglot {
 
     let session: Session
 
     /// The language to be translated from. It will automatically detect the language if you do not set this.
-    public var fromLanguage: Language?
+    open var fromLanguage: Language?
 
     /// The language to translate to.
-    public var toLanguage: Language
+    open var toLanguage: Language
 
 
     /**
@@ -143,7 +143,7 @@ public class Polyglot {
         - parameter text: The text to translate.
         - parameter callback: The code to be executed once the translation has completed.
     */
-    public func translate(text: String, callback: ((translation: String) -> (Void))) {
+    open func translate(_ text: String, callback: @escaping ((_ translation: String) -> (Void))) {
         session.getAccessToken { token in
             if self.fromLanguage == nil {
                 self.fromLanguage = text.language
@@ -152,15 +152,15 @@ public class Polyglot {
             let fromLanguageComponent = (self.fromLanguage != nil) ? "&from=\(self.fromLanguage!.rawValue.urlEncoded!)" : ""
             let urlString = "http://api.microsofttranslator.com/v2/Http.svc/Translate?text=\(text.urlEncoded!)\(toLanguageComponent)\(fromLanguageComponent)"
 
-            let request = NSMutableURLRequest(URL: NSURL(string: urlString)!)
-            request.HTTPMethod = "GET"
+            var request = URLRequest(url: URL(string: urlString)!)
+            request.httpMethod = "GET"
             request.setValue("Bearer " + token, forHTTPHeaderField: "Authorization")
 
-            let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {(data, response, error) in
+            let task = URLSession.shared.dataTask(with: request, completionHandler: {(data, response, error) in
                 let translation: String
                 guard
                     let data = data,
-                    let xmlString = NSString(data: data, encoding: NSUTF8StringEncoding) as? String
+                    let xmlString = NSString(data: data, encoding: String.Encoding.utf8.rawValue) as? String
                 else {
                     translation = ""
                     return
@@ -169,17 +169,17 @@ public class Polyglot {
                 translation = self.translationFromXML(xmlString)
 
                 defer {
-                    dispatch_async(dispatch_get_main_queue()) {
-                        callback(translation: translation)
+                    DispatchQueue.main.async {
+                        callback(translation)
                     }
                 }
-            }
+            }) 
             task.resume()
         }
     }
 
-    private func translationFromXML(XML: String) -> String {
-        let translation = XML.stringByReplacingOccurrencesOfString("<string xmlns=\"http://schemas.microsoft.com/2003/10/Serialization/\">", withString: "")
-        return translation.stringByReplacingOccurrencesOfString("</string>", withString: "")
+    fileprivate func translationFromXML(_ XML: String) -> String {
+        let translation = XML.replacingOccurrences(of: "<string xmlns=\"http://schemas.microsoft.com/2003/10/Serialization/\">", with: "")
+        return translation.replacingOccurrences(of: "</string>", with: "")
     }
 }
diff --git a/Polyglot/Session.swift b/Polyglot/Session.swift
index d54b45a..01a1fd6 100644
--- a/Polyglot/Session.swift
+++ b/Polyglot/Session.swift
@@ -28,47 +28,47 @@ class Session {
     let clientSecret: String
 
     var accessToken: String?
-    var expirationTime: NSDate?
+    var expirationTime: Date?
 
     init(clientId: String, clientSecret: String) {
         self.clientId = clientId
         self.clientSecret = clientSecret
     }
 
-    func getAccessToken(callback: ((token: String) -> (Void))) {
+    func getAccessToken(_ callback: @escaping ((_ token: String) -> (Void))) {
         if (accessToken == nil || isExpired) {
-            let url = NSURL(string: "https://datamarket.accesscontrol.windows.net/v2/OAuth2-13")
+            let url = URL(string: "https://datamarket.accesscontrol.windows.net/v2/OAuth2-13")
 
-            let request = NSMutableURLRequest(URL: url!)
-            request.HTTPMethod = "POST"
+            var request = URLRequest(url: url!)
+            request.httpMethod = "POST"
 
             let bodyString = "client_id=\(clientId.urlEncoded!)&client_secret=\(clientSecret.urlEncoded!)&scope=http://api.microsofttranslator.com&grant_type=client_credentials"
-            request.HTTPBody = bodyString.dataUsingEncoding(NSUTF8StringEncoding)
+            request.httpBody = bodyString.data(using: String.Encoding.utf8)
 
-            let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {(data, response, error) in
+            let task = URLSession.shared.dataTask(with: request, completionHandler: {(data, response, error) in
                 guard
                     let data = data,
-                    let resultsDict = try? NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers),
-                    let expiresIn = resultsDict["expires_in"] as? NSString
+                let resultsDict = try? JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions.mutableContainers) as? [String: Any],
+                    let expiresIn = resultsDict?["expires_in"] as? NSString
                 else {
-                    callback(token: "")
+                    callback("")
                     return
                 }
-                self.expirationTime = NSDate(timeIntervalSinceNow: expiresIn.doubleValue)
+                self.expirationTime = Date(timeIntervalSinceNow: expiresIn.doubleValue)
 
-                let token = resultsDict["access_token"] as! String
+                let token = resultsDict?["access_token"] as! String
                 self.accessToken = token
 
-                callback(token: token)
-            }
+                callback(token)
+            }) 
 
             task.resume()
         } else {
-            callback(token: accessToken!)
+            callback(accessToken!)
         }
     }
 
-    private var isExpired: Bool {
-        return expirationTime?.earlierDate(NSDate()) == self.expirationTime
+    fileprivate var isExpired: Bool {
+        return (expirationTime as NSDate?)?.earlierDate(Date()) == self.expirationTime
     }
 }
diff --git a/Polyglot/StringExtension.swift b/Polyglot/StringExtension.swift
index bfe1830..fbd6424 100644
--- a/Polyglot/StringExtension.swift
+++ b/Polyglot/StringExtension.swift
@@ -25,16 +25,16 @@ import Foundation
 extension String {
 
     public var urlEncoded: String? {
-        let urlQueryAllowedCharacterSet: NSMutableCharacterSet = NSCharacterSet.URLQueryAllowedCharacterSet().mutableCopy() as! NSMutableCharacterSet
-        urlQueryAllowedCharacterSet.removeCharactersInString("&=?+")
-        return self.stringByAddingPercentEncodingWithAllowedCharacters(urlQueryAllowedCharacterSet)
+        let urlQueryAllowedCharacterSet: NSMutableCharacterSet = (CharacterSet.urlQueryAllowed as NSCharacterSet).mutableCopy() as! NSMutableCharacterSet
+        urlQueryAllowedCharacterSet.removeCharacters(in: "&=?+")
+        return self.addingPercentEncoding(withAllowedCharacters: urlQueryAllowedCharacterSet as CharacterSet)
     }
     
     public var language: Language? {
         if characters.count > 0 { // Prevent Index Out of Bounds in NSLinguisticTagger
             let tagger = NSLinguisticTagger(tagSchemes: [NSLinguisticTagSchemeLanguage], options: 0)
             tagger.string = self
-            if let result = tagger.tagAtIndex(0, scheme: NSLinguisticTagSchemeLanguage, tokenRange: nil, sentenceRange: nil) {
+            if let result = tagger.tag(at: 0, scheme: NSLinguisticTagSchemeLanguage, tokenRange: nil, sentenceRange: nil) {
                 return Language(rawValue: result)
             }
         }
diff --git a/PolyglotTests/StringExtensionTests.swift b/PolyglotTests/StringExtensionTests.swift
index 3616a46..a77892e 100644
--- a/PolyglotTests/StringExtensionTests.swift
+++ b/PolyglotTests/StringExtensionTests.swift
@@ -39,7 +39,7 @@ class StringExtensionTests: XCTestCase {
         XCTAssertNil("".language?.rawValue, "Empty strings should return nil.")
     }
 
-    func AssertEqualOptional<T : Equatable>(@autoclosure optional:  () -> T?, @autoclosure _ expected:  () -> T, file: String = __FILE__, line: UInt = __LINE__) {
+    func AssertEqualOptional<T : Equatable>(@autoclosure optional:  () -> T?, @autoclosure _ expected:  () -> T, file: String = #file, line: UInt = #line) {
         if let nonOptional = optional() {
             if nonOptional != expected() {
                 self.recordFailureWithDescription("Optional (\(nonOptional)) is not equal to (\(expected()))", inFile: file, atLine: line, expected: true)