diff --git a/SwiftValidator/Core/Validator.swift b/SwiftValidator/Core/Validator.swift
index a7a1262..2553e47 100644
--- a/SwiftValidator/Core/Validator.swift
+++ b/SwiftValidator/Core/Validator.swift
@@ -20,9 +20,9 @@ public class Validator {
     /// Dictionary to hold fields by their object identifiers
     private var fields = ValidatorDictionary<Validatable>()
     /// Variable that holds success closure to display positive status of field.
-    private var successStyleTransform:((validationRule:ValidationRule)->Void)?
+    private var successStyleTransform:((_ validationRule:ValidationRule)->Void)?
     /// Variable that holds error closure to display negative status of field.
-    private var errorStyleTransform:((validationError:ValidationError)->Void)?
+    private var errorStyleTransform:((_ validationError:ValidationError)->Void)?
     /// - returns: An initialized object, or nil if an object could not be created for some reason that would not result in an exception.
     public init(){}
     
@@ -44,13 +44,13 @@ public class Validator {
                 
                 // let the user transform the field if they want
                 if let transform = self.errorStyleTransform {
-                    transform(validationError: error)
+                    transform(error)
                 }
             } else {
                 // No error
                 // let the user transform the field if they want
                 if let transform = self.successStyleTransform {
-                    transform(validationRule: rule)
+                    transform(rule)
                 }
             }
         }
@@ -65,22 +65,22 @@ public class Validator {
     - parameter field: Holds validator field data.
     - returns: No return value.
     */
-    public func validateField(_ field: ValidatableField, callback: (error:ValidationError?) -> Void){
+    public func validateField(_ field: ValidatableField, callback: (_ error:ValidationError?) -> Void){
         if let fieldRule = validations[field] {
             if let error = fieldRule.validateField() {
                 errors[field] = error
                 if let transform = self.errorStyleTransform {
-                    transform(validationError: error)
+                    transform(error)
                 }
-                callback(error: error)
+                callback(error)
             } else {
                 if let transform = self.successStyleTransform {
-                    transform(validationRule: fieldRule)
+                    transform(fieldRule)
                 }
-                callback(error: nil)
+                callback(nil)
             }
         } else {
-            callback(error: nil)
+            callback(nil)
         }
     }
     
@@ -93,7 +93,7 @@ public class Validator {
     - parameter error: A closure which is called with validationError, an object that holds validation error data
     - returns: No return value
     */
-    public func styleTransformers(success:((validationRule:ValidationRule)->Void)?, error:((validationError:ValidationError)->Void)?) {
+    public func styleTransformers(success:((_ validationRule:ValidationRule)->Void)?, error:((_ validationError:ValidationError)->Void)?) {
         self.successStyleTransform = success
         self.errorStyleTransform = error
     }
@@ -145,10 +145,10 @@ public class Validator {
      - parameter callback: A closure which is called with errors, a dictionary of type Validatable:ValidationError.
      - returns: No return value.
      */
-    public func validate(_ callback:(errors:[(Validatable, ValidationError)])->Void) -> Void {
+    public func validate(_ callback:(_ errors:[(Validatable, ValidationError)])->Void) -> Void {
         
         self.validateAllFields()
         
-        callback(errors: errors.map { (fields[$1.field]!, $1) } )
+        callback(errors.map { (fields[$1.field]!, $1) } )
     }
 }
diff --git a/SwiftValidator/Rules/CharacterSetRule.swift b/SwiftValidator/Rules/CharacterSetRule.swift
index 01ec8b0..d897132 100644
--- a/SwiftValidator/Rules/CharacterSetRule.swift
+++ b/SwiftValidator/Rules/CharacterSetRule.swift
@@ -37,7 +37,7 @@ public class CharacterSetRule: Rule {
      */
     public func validate(_ value: String) -> Bool {
         for uni in value.unicodeScalars {
-            if !characterSet.contains(UnicodeScalar(uni.value)) {
+            guard let uniVal = UnicodeScalar(uni.value), characterSet.contains(uniVal) else {
                 return false
             }
         }
diff --git a/SwiftValidator/Rules/ExactLengthRule.swift b/SwiftValidator/Rules/ExactLengthRule.swift
index d5b2b33..c9aae6d 100644
--- a/SwiftValidator/Rules/ExactLengthRule.swift
+++ b/SwiftValidator/Rules/ExactLengthRule.swift
@@ -26,7 +26,7 @@ public class ExactLengthRule : Rule {
      */
     public init(length: Int, message : String = "Must be exactly %ld characters long"){
         self.length = length
-        self.message = NSString(format: message, self.length) as String
+        self.message = String(format: message, self.length)
     }
     
     /**
diff --git a/SwiftValidator/Rules/ISBNRule.swift b/SwiftValidator/Rules/ISBNRule.swift
index f715cdf..6f8654f 100644
--- a/SwiftValidator/Rules/ISBNRule.swift
+++ b/SwiftValidator/Rules/ISBNRule.swift
@@ -136,7 +136,7 @@ private struct ISBN10Validator: ISBNValidator {
      - parameter input: String that is checked for ISBN10 validation.
      - returns: `true` if string is a valid ISBN10 and `false` if it is not.
     */
-    private func verifyChecksum(_ input: String) -> Bool {
+    fileprivate func verifyChecksum(_ input: String) -> Bool {
         var checksum = 0
         
         for i in 0..<9 {
@@ -171,7 +171,7 @@ private struct ISBN13Validator: ISBNValidator {
      - parameter input: String that is checked for ISBN13 validation.
      - returns: `true` if string is a valid ISBN13 and `false` if it is not.
      */
-    private func verifyChecksum(_ input: String) -> Bool {
+    fileprivate func verifyChecksum(_ input: String) -> Bool {
         let factor = [1, 3]
         var checksum = 0
         
diff --git a/SwiftValidator/Rules/MaxLengthRule.swift b/SwiftValidator/Rules/MaxLengthRule.swift
index 43aa535..57d9b7b 100644
--- a/SwiftValidator/Rules/MaxLengthRule.swift
+++ b/SwiftValidator/Rules/MaxLengthRule.swift
@@ -27,7 +27,7 @@ public class MaxLengthRule: Rule {
      */
     public init(length: Int, message : String = "Must be at most %ld characters long"){
         self.DEFAULT_LENGTH = length
-        self.message = NSString(format: message, self.DEFAULT_LENGTH) as String
+        self.message = String(format: message, self.DEFAULT_LENGTH)
     }
     
     /**
diff --git a/SwiftValidator/Rules/MinLengthRule.swift b/SwiftValidator/Rules/MinLengthRule.swift
index e13a330..d9e161c 100644
--- a/SwiftValidator/Rules/MinLengthRule.swift
+++ b/SwiftValidator/Rules/MinLengthRule.swift
@@ -29,7 +29,7 @@ public class MinLengthRule: Rule {
      */
     public init(length: Int, message : String = "Must be at least %ld characters long"){
         self.DEFAULT_LENGTH = length
-        self.message = NSString(format: message, self.DEFAULT_LENGTH) as String
+        self.message = String(format: message, self.DEFAULT_LENGTH)
     }
     
     /**
diff --git a/SwiftValidator/Rules/ValidationRule.swift b/SwiftValidator/Rules/ValidationRule.swift
index 9bf2655..ef8d306 100644
--- a/SwiftValidator/Rules/ValidationRule.swift
+++ b/SwiftValidator/Rules/ValidationRule.swift
@@ -39,7 +39,7 @@ public class ValidationRule {
      */
     public func validateField() -> ValidationError? {
         return rules.filter{
-            return !$0.validate(field.validationText ?? "")
+            return !$0.validate(field.validationText)
             }.map{ rule -> ValidationError in return ValidationError(field: self.field, errorLabel:self.errorLabel, error: rule.errorMessage()) }.first
     }
-}
\ No newline at end of file
+}
diff --git a/SwiftValidatorTests/SwiftValidatorTests.swift b/SwiftValidatorTests/SwiftValidatorTests.swift
index 1b063e9..fab19bc 100644
--- a/SwiftValidatorTests/SwiftValidatorTests.swift
+++ b/SwiftValidatorTests/SwiftValidatorTests.swift
@@ -366,7 +366,7 @@ class SwiftValidatorTests: XCTestCase {
         }
         REGISTER_TXT_FIELD.text = INVALID_EMAIL
         REGISTER_VALIDATOR.validateField(REGISTER_TXT_FIELD) { error in
-            XCTAssert(error?.errorMessage.characters.count > 0, "Should state 'invalid email'")
+            XCTAssert(error?.errorMessage.characters.count ?? 0 > 0, "Should state 'invalid email'")
         }
     }
     
diff --git a/Validator/AppDelegate.swift b/Validator/AppDelegate.swift
index 46a16ba..a68462f 100644
--- a/Validator/AppDelegate.swift
+++ b/Validator/AppDelegate.swift
@@ -14,7 +14,7 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
     var window: UIWindow?
 
 
-    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
+    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
         // Override point for customization after application launch.
         return true
     }