diff --git a/AndroidCalculator.xcodeproj/project.pbxproj b/AndroidCalculator.xcodeproj/project.pbxproj
index 6703289..d208169 100644
--- a/AndroidCalculator.xcodeproj/project.pbxproj
+++ b/AndroidCalculator.xcodeproj/project.pbxproj
@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		2510194524607F2200110EA6 /* Calculator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2510194424607F2200110EA6 /* Calculator.swift */; };
 		25EDCE93245F3DFA00ECF5A2 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 25EDCE92245F3DFA00ECF5A2 /* AppDelegate.swift */; };
 		25EDCE95245F3DFA00ECF5A2 /* SceneDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 25EDCE94245F3DFA00ECF5A2 /* SceneDelegate.swift */; };
 		25EDCE97245F3DFA00ECF5A2 /* ViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 25EDCE96245F3DFA00ECF5A2 /* ViewController.swift */; };
@@ -16,6 +17,7 @@
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
+		2510194424607F2200110EA6 /* Calculator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Calculator.swift; sourceTree = "<group>"; };
 		25EDCE8F245F3DFA00ECF5A2 /* AndroidCalculator.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = AndroidCalculator.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		25EDCE92245F3DFA00ECF5A2 /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
 		25EDCE94245F3DFA00ECF5A2 /* SceneDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SceneDelegate.swift; sourceTree = "<group>"; };
@@ -63,6 +65,7 @@
 				25EDCE9B245F3DFC00ECF5A2 /* Assets.xcassets */,
 				25EDCE9D245F3DFC00ECF5A2 /* LaunchScreen.storyboard */,
 				25EDCEA0245F3DFC00ECF5A2 /* Info.plist */,
+				2510194424607F2200110EA6 /* Calculator.swift */,
 			);
 			path = AndroidCalculator;
 			sourceTree = "<group>";
@@ -139,6 +142,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				25EDCE97245F3DFA00ECF5A2 /* ViewController.swift in Sources */,
+				2510194524607F2200110EA6 /* Calculator.swift in Sources */,
 				25EDCE93245F3DFA00ECF5A2 /* AppDelegate.swift in Sources */,
 				25EDCE95245F3DFA00ECF5A2 /* SceneDelegate.swift in Sources */,
 			);
diff --git a/AndroidCalculator/Calculator.swift b/AndroidCalculator/Calculator.swift
new file mode 100644
index 0000000..e32e986
--- /dev/null
+++ b/AndroidCalculator/Calculator.swift
@@ -0,0 +1,15 @@
+//
+//  Calculator.swift
+//  AndroidCalculator
+//
+//  Created by Pin Lin on 2020/5/5.
+//  Copyright © 2020 Pin Lin. All rights reserved.
+//
+
+import Foundation
+
+class Calculator {
+  func clickNumber(_ number: Int) {
+    print(number)
+  }
+}
diff --git a/AndroidCalculator/ViewController.swift b/AndroidCalculator/ViewController.swift
index 741e6b5..0bb566a 100644
--- a/AndroidCalculator/ViewController.swift
+++ b/AndroidCalculator/ViewController.swift
@@ -15,8 +15,11 @@ class ViewController: UIViewController {
   @IBOutlet weak var resultLabel: UILabel!
   @IBOutlet var numberButtons: [UIButton]!
   
+  var calculator: Calculator = Calculator()
+  
   @IBAction func clickNumberButton(_ sender: UIButton) {
-    print(numberButtons.firstIndex(of: sender)!)
+    let number = numberButtons.firstIndex(of: sender)!
+    calculator.clickNumber(number)
   }
   
   override func viewDidLoad() {