diff --git a/DOAlertController-DEMO/DOAlertController-DEMO.xcodeproj/project.pbxproj b/DOAlertController-DEMO/DOAlertController-DEMO.xcodeproj/project.pbxproj
index 7fae7d2..e9df7b6 100644
--- a/DOAlertController-DEMO/DOAlertController-DEMO.xcodeproj/project.pbxproj
+++ b/DOAlertController-DEMO/DOAlertController-DEMO.xcodeproj/project.pbxproj
@@ -169,7 +169,7 @@
 			attributes = {
 				LastSwiftMigration = 0710;
 				LastSwiftUpdateCheck = 0710;
-				LastUpgradeCheck = 0800;
+				LastUpgradeCheck = 0920;
 				ORGANIZATIONNAME = "Daiki Okumura";
 				TargetAttributes = {
 					4F47CAAA1AE26BD100BF71E4 = {
@@ -178,6 +178,7 @@
 					};
 					4F47CABF1AE26BD100BF71E4 = {
 						CreatedOnToolsVersion = 6.2;
+						LastSwiftMigration = 0920;
 						TestTargetID = 4F47CAAA1AE26BD100BF71E4;
 					};
 				};
@@ -278,14 +279,20 @@
 				CLANG_CXX_LIBRARY = "libc++";
 				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_ARC = YES;
+				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
 				CLANG_WARN_BOOL_CONVERSION = YES;
+				CLANG_WARN_COMMA = YES;
 				CLANG_WARN_CONSTANT_CONVERSION = YES;
 				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
 				CLANG_WARN_EMPTY_BODY = YES;
 				CLANG_WARN_ENUM_CONVERSION = YES;
 				CLANG_WARN_INFINITE_RECURSION = YES;
 				CLANG_WARN_INT_CONVERSION = YES;
+				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
+				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
+				CLANG_WARN_STRICT_PROTOTYPES = YES;
 				CLANG_WARN_SUSPICIOUS_MOVE = YES;
 				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
@@ -325,14 +332,20 @@
 				CLANG_CXX_LIBRARY = "libc++";
 				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_ARC = YES;
+				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
 				CLANG_WARN_BOOL_CONVERSION = YES;
+				CLANG_WARN_COMMA = YES;
 				CLANG_WARN_CONSTANT_CONVERSION = YES;
 				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
 				CLANG_WARN_EMPTY_BODY = YES;
 				CLANG_WARN_ENUM_CONVERSION = YES;
 				CLANG_WARN_INFINITE_RECURSION = YES;
 				CLANG_WARN_INT_CONVERSION = YES;
+				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
+				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
+				CLANG_WARN_STRICT_PROTOTYPES = YES;
 				CLANG_WARN_SUSPICIOUS_MOVE = YES;
 				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
@@ -367,7 +380,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "co.devlog.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Debug;
@@ -382,7 +395,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "co.devlog.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Release;
@@ -403,6 +416,8 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "co.devlog.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_SWIFT3_OBJC_INFERENCE = On;
+				SWIFT_VERSION = 4.0;
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/DOAlertController-DEMO.app/DOAlertController-DEMO";
 			};
 			name = Debug;
@@ -419,6 +434,8 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "co.devlog.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_SWIFT3_OBJC_INFERENCE = On;
+				SWIFT_VERSION = 4.0;
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/DOAlertController-DEMO.app/DOAlertController-DEMO";
 			};
 			name = Release;
diff --git a/DOAlertController-DEMO/DOAlertController-DEMO/DOAlertController.swift b/DOAlertController-DEMO/DOAlertController-DEMO/DOAlertController.swift
index e078ead..e9d7a26 100644
--- a/DOAlertController-DEMO/DOAlertController-DEMO/DOAlertController.swift
+++ b/DOAlertController-DEMO/DOAlertController-DEMO/DOAlertController.swift
@@ -627,23 +627,25 @@ open class DOAlertController : UIViewController, UITextFieldDelegate, UIViewCont
     }
     
     // Button Tapped Action
-    func buttonTapped(_ sender: UIButton) {
+    @objc func buttonTapped(_ sender: UIButton) {
         sender.isSelected = true
         let action = actions[sender.tag - 1] as! DOAlertAction
-        if (action.handler != nil) {
-            action.handler(action)
-        }
-        self.dismiss(animated: true, completion: nil)
+        self.dismiss(animated: true, completion:{
+            if (action.handler != nil) {
+                action.handler(action)
+            }
+        })
     }
     
     // Handle ContainerView tap gesture
-    func handleContainerViewTapGesture(_ sender: AnyObject) {
+    @objc func handleContainerViewTapGesture(_ sender: AnyObject) {
         // cancel action
         let action = actions[cancelButtonTag - 1] as! DOAlertAction
-        if (action.handler != nil) {
-            action.handler(action)
-        }
-        self.dismiss(animated: true, completion: nil)
+        self.dismiss(animated: true, completion:{
+            if (action.handler != nil) {
+                action.handler(action)
+            }
+        })
     }
     
     // UIColor -> UIImage
@@ -662,11 +664,11 @@ open class DOAlertController : UIViewController, UITextFieldDelegate, UIViewCont
     
     @objc func handleAlertActionEnabledDidChangeNotification(_ notification: Notification) {
         for i in 0..<buttons.count {
-            buttons[i].isEnabled = actions[i].enabled
+            buttons[i].isEnabled = (actions[i] as! DOAlertAction).enabled
         }
     }
     
-    func handleKeyboardWillShowNotification(_ notification: Notification) {
+    @objc func handleKeyboardWillShowNotification(_ notification: Notification) {
         if let userInfo = notification.userInfo as? [String: NSValue],
             let keyboardSize = userInfo[UIKeyboardFrameEndUserInfoKey]?.cgRectValue.size {
             var _keyboardSize = keyboardSize
@@ -684,7 +686,7 @@ open class DOAlertController : UIViewController, UITextFieldDelegate, UIViewCont
         }
     }
     
-    func handleKeyboardWillHideNotification(_ notification: Notification) {
+    @objc func handleKeyboardWillHideNotification(_ notification: Notification) {
         keyboardHeight = 0.0
         reloadAlertViewHeight()
         containerViewBottomSpaceConstraint?.constant = keyboardHeight
diff --git a/DOAlertController-DEMO/DOAlertController-DEMO/ViewController.swift b/DOAlertController-DEMO/DOAlertController-DEMO/ViewController.swift
index 7f4b17a..53156f1 100644
--- a/DOAlertController-DEMO/DOAlertController-DEMO/ViewController.swift
+++ b/DOAlertController-DEMO/DOAlertController-DEMO/ViewController.swift
@@ -52,6 +52,9 @@ class ViewController : UITableViewController, UITextFieldDelegate {
         // Create the action.
         let cancelAction = DOAlertAction(title: cancelButtonTitle, style: .cancel) { action in
             NSLog("The simple alert's cancel action occured.")
+            let systemAlertController = UIAlertController(title: "Test present after completion", message: nil, preferredStyle: .alert)
+            systemAlertController.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
+            self.present(systemAlertController, animated: true, completion: nil)
         }
         
         // Add the action.
@@ -172,7 +175,7 @@ class ViewController : UITableViewController, UITextFieldDelegate {
         }
         
         // Stop listening for text change notifications on the text field. This closure will be called in the two action handlers.
-        let removeTextFieldObserver: (Void) -> Void = {
+        let removeTextFieldObserver: () -> Void = {
             NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UITextFieldTextDidChange, object: alertController.textFields!.first)
         }
         
@@ -391,11 +394,11 @@ class ViewController : UITableViewController, UITextFieldDelegate {
     
     // MARK: UITextFieldTextDidChangeNotification
     
-    func handleTextFieldTextDidChangeNotification(_ notification: Notification) {
+    @objc func handleTextFieldTextDidChangeNotification(_ notification: Notification) {
         let textField = notification.object as! UITextField
         
         // Enforce a minimum length of >= 5 characters for secure text alerts.
-        secureTextAlertAction!.enabled = textField.text!.characters.count >= 5
+        secureTextAlertAction!.enabled = textField.text!.count >= 5
     }
     
     // MARK: UITextFieldDelegate Methods
diff --git a/DOAlertController-DEMO/DOAlertController-DEMOTests/DOAlertController_DEMOTests.swift b/DOAlertController-DEMO/DOAlertController-DEMOTests/DOAlertController_DEMOTests.swift
index 2d2eabe..5b3035a 100644
--- a/DOAlertController-DEMO/DOAlertController-DEMOTests/DOAlertController_DEMOTests.swift
+++ b/DOAlertController-DEMO/DOAlertController-DEMOTests/DOAlertController_DEMOTests.swift
@@ -28,7 +28,7 @@ class DOAlertController_DEMOTests: XCTestCase {
     
     func testPerformanceExample() {
         // This is an example of a performance test case.
-        self.measureBlock() {
+        self.measure() {
             // Put the code you want to measure the time of here.
         }
     }