diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..bd7480a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+.DS_Store
+xcuserdata/
\ No newline at end of file
diff --git a/.swift-version b/.swift-version
index 9f55b2c..5186d07 100644
--- a/.swift-version
+++ b/.swift-version
@@ -1 +1 @@
-3.0
+4.0
diff --git a/RandomUserSwift.xcodeproj/project.pbxproj b/RandomUserSwift.xcodeproj/project.pbxproj
index bec5f6d..7370c0b 100644
--- a/RandomUserSwift.xcodeproj/project.pbxproj
+++ b/RandomUserSwift.xcodeproj/project.pbxproj
@@ -149,18 +149,19 @@
 			isa = PBXProject;
 			attributes = {
 				LastSwiftUpdateCheck = 0800;
-				LastUpgradeCheck = 0810;
+				LastUpgradeCheck = 0920;
 				ORGANIZATIONNAME = "Wilson Ding";
 				TargetAttributes = {
 					C8A7AA241DAC2FE80054C75C = {
 						CreatedOnToolsVersion = 8.0;
 						DevelopmentTeam = 585SNYAD83;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0920;
 						ProvisioningStyle = Automatic;
 					};
 					C8A7AA2D1DAC2FE90054C75C = {
 						CreatedOnToolsVersion = 8.0;
 						DevelopmentTeam = 585SNYAD83;
+						LastSwiftMigration = 0920;
 						ProvisioningStyle = Automatic;
 					};
 				};
@@ -238,7 +239,9 @@
 				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_DOCUMENTATION_COMMENTS = YES;
@@ -246,7 +249,11 @@
 				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_SUSPICIOUS_MOVES = YES;
 				CLANG_WARN_UNREACHABLE_CODE = YES;
@@ -292,7 +299,9 @@
 				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_DOCUMENTATION_COMMENTS = YES;
@@ -300,7 +309,11 @@
 				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_SUSPICIOUS_MOVES = YES;
 				CLANG_WARN_UNREACHABLE_CODE = YES;
@@ -347,7 +360,8 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 3.0;
+				SWIFT_SWIFT3_OBJC_INFERENCE = On;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -367,7 +381,8 @@
 				PRODUCT_BUNDLE_IDENTIFIER = com.wilsonding.RandomUserSwift;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 3.0;
+				SWIFT_SWIFT3_OBJC_INFERENCE = On;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};
@@ -380,7 +395,8 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.wilsonding.RandomUserSwiftTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0;
+				SWIFT_SWIFT3_OBJC_INFERENCE = On;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -393,7 +409,8 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.wilsonding.RandomUserSwiftTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 3.0;
+				SWIFT_SWIFT3_OBJC_INFERENCE = On;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};
diff --git a/RandomUserSwift.xcodeproj/project.xcworkspace/xcuserdata/quanvo.xcuserdatad/UserInterfaceState.xcuserstate b/RandomUserSwift.xcodeproj/project.xcworkspace/xcuserdata/quanvo.xcuserdatad/UserInterfaceState.xcuserstate
deleted file mode 100644
index 69d8216..0000000
Binary files a/RandomUserSwift.xcodeproj/project.xcworkspace/xcuserdata/quanvo.xcuserdatad/UserInterfaceState.xcuserstate and /dev/null differ
diff --git a/RandomUserSwift.xcodeproj/project.xcworkspace/xcuserdata/wilson.xcuserdatad/UserInterfaceState.xcuserstate b/RandomUserSwift.xcodeproj/project.xcworkspace/xcuserdata/wilson.xcuserdatad/UserInterfaceState.xcuserstate
deleted file mode 100644
index c6e67ec..0000000
Binary files a/RandomUserSwift.xcodeproj/project.xcworkspace/xcuserdata/wilson.xcuserdatad/UserInterfaceState.xcuserstate and /dev/null differ
diff --git a/RandomUserSwift.xcodeproj/xcshareddata/xcschemes/RandomUserSwift.xcscheme b/RandomUserSwift.xcodeproj/xcshareddata/xcschemes/RandomUserSwift.xcscheme
index 4d036f1..db15d3a 100644
--- a/RandomUserSwift.xcodeproj/xcshareddata/xcschemes/RandomUserSwift.xcscheme
+++ b/RandomUserSwift.xcodeproj/xcshareddata/xcschemes/RandomUserSwift.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0810"
+   LastUpgradeVersion = "0920"
    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"