diff --git a/.travis.yml b/.travis.yml
index 99858c0..78a2911 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,5 @@
 language: objective-c
-osx_image: xcode8.1
+osx_image: xcode9.1
 env:
   global:
   - LC_CTYPE=en_US.UTF-8
@@ -10,7 +10,7 @@ env:
   #- WATCHOS_FRAMEWORK_SCHEME="QRCode-watchOS"
   matrix:
     #- DESTINATION="OS=9.3,name=iPhone 6S"           SCHEME="$IOS_FRAMEWORK_SCHEME"      SDK="iphonesimulator9.3"
-    - DESTINATION="OS=10.1,name=iPhone 6S"          SCHEME="$IOS_FRAMEWORK_SCHEME"      SDK="iphonesimulator10.1"
+    - DESTINATION="OS=11.1,name=iPhone 8"          SCHEME="$IOS_FRAMEWORK_SCHEME"      SDK="iphonesimulator11.1"
     #- DESTINATION="OS=9.2,name=Apple TV 1080p"      SCHEME="$TVOS_FRAMEWORK_SCHEME"     SDK="appletvsimulator9.2"
     #- DESTINATION="OS=2.2,name=Apple Watch - 42mm"  SCHEME="$WATCHOS_FRAMEWORK_SCHEME"  SDK="watchsimulator2.2"
     #- DESTINATION="OS=10.0,name=Apple TV 1080p"     SCHEME="$TVOS_FRAMEWORK_SCHEME"     SDK="appletvsimulator10.0"
diff --git a/Example.xcodeproj/project.pbxproj b/Example.xcodeproj/project.pbxproj
index 042dddb..17dfa54 100644
--- a/Example.xcodeproj/project.pbxproj
+++ b/Example.xcodeproj/project.pbxproj
@@ -265,20 +265,20 @@
 			attributes = {
 				LastSwiftMigration = 0700;
 				LastSwiftUpdateCheck = 0700;
-				LastUpgradeCheck = 0800;
+				LastUpgradeCheck = 0910;
 				ORGANIZATIONNAME = "Alexander Schuch";
 				TargetAttributes = {
 					4D248F061A751C3700E44E6B = {
 						CreatedOnToolsVersion = 6.2;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0910;
 					};
 					4D248F301A751C7800E44E6B = {
 						CreatedOnToolsVersion = 6.2;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0910;
 					};
 					4D248F3A1A751C7800E44E6B = {
 						CreatedOnToolsVersion = 6.2;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0910;
 						TestTargetID = 4D248F061A751C3700E44E6B;
 					};
 				};
@@ -407,14 +407,20 @@
 				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;
@@ -454,14 +460,20 @@
 				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;
@@ -495,7 +507,8 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "com.aschuch.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0.1;
+				SWIFT_SWIFT3_OBJC_INFERENCE = Off;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -508,7 +521,8 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "com.aschuch.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0.1;
+				SWIFT_SWIFT3_OBJC_INFERENCE = Off;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};
@@ -534,7 +548,8 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 3.0.1;
+				SWIFT_SWIFT3_OBJC_INFERENCE = Off;
+				SWIFT_VERSION = 4.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
@@ -558,7 +573,8 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "com.aschuch.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 3.0.1;
+				SWIFT_SWIFT3_OBJC_INFERENCE = Off;
+				SWIFT_VERSION = 4.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
@@ -577,7 +593,8 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "com.aschuch.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0.1;
+				SWIFT_SWIFT3_OBJC_INFERENCE = Off;
+				SWIFT_VERSION = 4.0;
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/Example.app/Example";
 			};
 			name = Debug;
@@ -590,7 +607,8 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "com.aschuch.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0.1;
+				SWIFT_SWIFT3_OBJC_INFERENCE = Off;
+				SWIFT_VERSION = 4.0;
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/Example.app/Example";
 			};
 			name = Release;
diff --git a/Example.xcodeproj/xcshareddata/xcschemes/QRCode.xcscheme b/Example.xcodeproj/xcshareddata/xcschemes/QRCode.xcscheme
index 820d857..ab86177 100644
--- a/Example.xcodeproj/xcshareddata/xcschemes/QRCode.xcscheme
+++ b/Example.xcodeproj/xcshareddata/xcschemes/QRCode.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0800"
+   LastUpgradeVersion = "0910"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
@@ -26,6 +26,7 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      language = ""
       shouldUseLaunchSchemeArgsEnv = "YES"
       codeCoverageEnabled = "YES">
       <Testables>
@@ -56,6 +57,7 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      language = ""
       launchStyle = "0"
       useCustomWorkingDirectory = "NO"
       ignoresPersistentStateOnLaunch = "NO"
diff --git a/Example.xcodeproj/xcshareddata/xcschemes/QRCodeTests.xcscheme b/Example.xcodeproj/xcshareddata/xcschemes/QRCodeTests.xcscheme
index 44264cb..ad61162 100644
--- a/Example.xcodeproj/xcshareddata/xcschemes/QRCodeTests.xcscheme
+++ b/Example.xcodeproj/xcshareddata/xcschemes/QRCodeTests.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0800"
+   LastUpgradeVersion = "0910"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
@@ -26,6 +26,7 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      language = ""
       shouldUseLaunchSchemeArgsEnv = "YES">
       <Testables>
          <TestableReference
@@ -55,6 +56,7 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      language = ""
       launchStyle = "0"
       useCustomWorkingDirectory = "NO"
       ignoresPersistentStateOnLaunch = "NO"
diff --git a/QRCode/CIColorExtension.swift b/QRCode/CIColorExtension.swift
index 40b4435..44dd23b 100644
--- a/QRCode/CIColorExtension.swift
+++ b/QRCode/CIColorExtension.swift
@@ -29,7 +29,7 @@ public extension CIColor {
         var hexValue: CUnsignedLongLong = 0
         
         if scanner.scanHexInt64(&hexValue) {
-            let length = rgba.characters.count
+            let length = rgba.count
             
             switch (length) {
             case 3: