diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..a1a118c
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "CarthageScripts"]
+	path = CarthageScripts
+	url = https://github.com/flinto/CarthageScripts.git
diff --git a/.travis.yml b/.travis.yml
index b134812..9431cf9 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,7 +11,7 @@ before_install:
 script: xcodebuild test -scheme RK4Spring_iOS -sdk iphonesimulator -destination 'platform=iOS
   Simulator,name=iPhone 7,OS=11.0'
 before_deploy:
-- ./script/build.sh --no-skip-current
+- ./CarthageScripts/build-static-framework.sh
 - carthage archive $FRAMEWORK_NAME
 deploy:
   provider: releases
diff --git a/CarthageScripts b/CarthageScripts
new file mode 160000
index 0000000..5eddecb
--- /dev/null
+++ b/CarthageScripts
@@ -0,0 +1 @@
+Subproject commit 5eddecb42cbe14da3c41030b1bdee562e64f6e2f
diff --git a/RK4SpringDemo.xcodeproj/project.pbxproj b/RK4SpringDemo.xcodeproj/project.pbxproj
index c1a06f5..3064b77 100644
--- a/RK4SpringDemo.xcodeproj/project.pbxproj
+++ b/RK4SpringDemo.xcodeproj/project.pbxproj
@@ -199,6 +199,7 @@
 				6E3BBB531F1E757800894AF1 /* Frameworks */,
 				6E3BBB541F1E757800894AF1 /* Headers */,
 				6E3BBB551F1E757800894AF1 /* Resources */,
+				6EDE4D551F1EA742007374E1 /* Copy framework to Carthage folder */,
 			);
 			buildRules = (
 			);
@@ -217,6 +218,7 @@
 				6E3BBB651F1E759800894AF1 /* Frameworks */,
 				6E3BBB661F1E759800894AF1 /* Headers */,
 				6E3BBB671F1E759800894AF1 /* Resources */,
+				6EE360371F1EB3E80055A1DB /* Copy framework to Carthage folder */,
 			);
 			buildRules = (
 			);
@@ -276,6 +278,7 @@
 				TargetAttributes = {
 					6E3BBB561F1E757800894AF1 = {
 						CreatedOnToolsVersion = 9.0;
+						LastSwiftMigration = 0900;
 					};
 					6E3BBB681F1E759800894AF1 = {
 						CreatedOnToolsVersion = 9.0;
@@ -287,7 +290,7 @@
 					};
 					6E3C28B51C20A02200CAD137 = {
 						CreatedOnToolsVersion = 7.2;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0900;
 					};
 				};
 			};
@@ -345,6 +348,37 @@
 		};
 /* End PBXResourcesBuildPhase section */
 
+/* Begin PBXShellScriptBuildPhase section */
+		6EDE4D551F1EA742007374E1 /* Copy framework to Carthage folder */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputPaths = (
+			);
+			name = "Copy framework to Carthage folder";
+			outputPaths = (
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "$SRCROOT/CarthageScripts/copy_framework.sh\n        ";
+		};
+		6EE360371F1EB3E80055A1DB /* Copy framework to Carthage folder */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputPaths = (
+			);
+			name = "Copy framework to Carthage folder";
+			outputPaths = (
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "$SRCROOT/CarthageScripts/copy_framework.sh\n";
+		};
+/* End PBXShellScriptBuildPhase section */
+
 /* Begin PBXSourcesBuildPhase section */
 		6E3BBB521F1E757800894AF1 /* Sources */ = {
 			isa = PBXSourcesBuildPhase;
@@ -728,7 +762,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/../Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.flinto.RK4SpringDemo;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -742,7 +776,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/../Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.flinto.RK4SpringDemo;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};
diff --git a/RK4SpringDemo/ViewController.swift b/RK4SpringDemo/ViewController.swift
index e4726c7..8fe972f 100644
--- a/RK4SpringDemo/ViewController.swift
+++ b/RK4SpringDemo/ViewController.swift
@@ -7,6 +7,7 @@
 //
 
 import Cocoa
+import RK4Spring
 
 class CustomView : NSView {
 
@@ -16,9 +17,9 @@ class CustomView : NSView {
 
 class ViewController: NSViewController {
 
-  dynamic var tension:Double  = 950
-  dynamic var friction:Double = 60
-  dynamic var velocity:Double = 0
+  @objc dynamic var tension:Double  = 950
+  @objc dynamic var friction:Double = 60
+  @objc dynamic var velocity:Double = 0
 
   @IBOutlet weak var customView:CustomView!
   var shape:CAShapeLayer!
diff --git a/script/build.sh b/script/build.sh
deleted file mode 100755
index 3b551f0..0000000
--- a/script/build.sh
+++ /dev/null
@@ -1,11 +0,0 @@
-#!/bin/sh -e
-
-xcconfig=$(mktemp /tmp/static.xcconfig.XXXXXX)
-trap 'rm -f "$xcconfig"' INT TERM HUP EXIT
-
-echo "LD = $PWD/script/ld.py" >> $xcconfig
-echo "DEBUG_INFORMATION_FORMAT = dwarf" >> $xcconfig
-
-export XCODE_XCCONFIG_FILE="$xcconfig"
-
-carthage build "$@"
\ No newline at end of file
diff --git a/script/ld.py b/script/ld.py
deleted file mode 100755
index c86bc48..0000000
--- a/script/ld.py
+++ /dev/null
@@ -1,32 +0,0 @@
-#!/usr/bin/env python
-
-import argparse
-import subprocess
-
-
-def ld_command(arch, isysroot, filelist, output):
-    return [
-        "libtool",
-        "-static",
-        "-arch_only", arch,
-        "-syslibroot", isysroot,
-        "-filelist", filelist,
-        "-o", output,
-    ]
-
-
-def build_parser():
-    parser = argparse.ArgumentParser()
-    parser.add_argument("-arch", required=True)
-    parser.add_argument("-isysroot", required=True)
-    parser.add_argument("-filelist", required=True)
-    parser.add_argument("-o", dest="output", required=True)
-    return parser
-
-if __name__ == "__main__":
-    arguments, _ = build_parser().parse_known_args()
-    command = ld_command(arguments.arch, arguments.isysroot,
-                         arguments.filelist, arguments.output)
-    print("-------------------------------------------------------------")
-    print(" ".join(command))
-    print(subprocess.check_output(command))
\ No newline at end of file