diff --git a/.travis.yml b/.travis.yml
index 0952679..76bcd28 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,5 @@
 language: objective-c
-osx_image: xcode8
+osx_image: xcode10.1
 before_install:
   - gem install xcpretty -N
 script:
diff --git a/SwiftCSV.xcodeproj/project.pbxproj b/SwiftCSV.xcodeproj/project.pbxproj
index 2e3223f..3a8eadd 100644
--- a/SwiftCSV.xcodeproj/project.pbxproj
+++ b/SwiftCSV.xcodeproj/project.pbxproj
@@ -418,39 +418,39 @@
 			attributes = {
 				LastSwiftMigration = 0700;
 				LastSwiftUpdateCheck = 0730;
-				LastUpgradeCheck = 0800;
+				LastUpgradeCheck = 0940;
 				ORGANIZATIONNAME = "Naoto Kaneko";
 				TargetAttributes = {
 					3D1E59B31945FFAC001CF760 = {
 						CreatedOnToolsVersion = 6.0;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0940;
 						ProvisioningStyle = Manual;
 					};
 					3D1E59BE1945FFAD001CF760 = {
 						CreatedOnToolsVersion = 6.0;
 						DevelopmentTeam = 2X7R4W3Y3Q;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0940;
 						TestTargetID = 3D1E59B31945FFAC001CF760;
 					};
 					5FB74B901CCB9274009DDBF1 = {
 						CreatedOnToolsVersion = 7.3;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0940;
 					};
 					5FB74B991CCB9274009DDBF1 = {
 						CreatedOnToolsVersion = 7.3;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0940;
 					};
 					5FB74BAC1CCB929D009DDBF1 = {
 						CreatedOnToolsVersion = 7.3;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0940;
 					};
 					5FB74BB51CCB929D009DDBF1 = {
 						CreatedOnToolsVersion = 7.3;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0940;
 					};
 					5FB74BC81CCB92BA009DDBF1 = {
 						CreatedOnToolsVersion = 7.3;
-						LastSwiftMigration = 0800;
+						LastSwiftMigration = 0940;
 					};
 				};
 			};
@@ -672,14 +672,22 @@
 				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_DEPRECATED_OBJC_IMPLEMENTATIONS = 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_IMPLICIT_RETAIN_SELF = 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;
@@ -722,14 +730,22 @@
 				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_DEPRECATED_OBJC_IMPLEMENTATIONS = 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_IMPLICIT_RETAIN_SELF = 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;
@@ -773,7 +789,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -792,7 +808,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "naoty.${PRODUCT_NAME:rfc1034identifier}";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};
@@ -813,7 +829,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SDKROOT = iphoneos;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -829,7 +845,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "naoty.${PRODUCT_NAME:rfc1034identifier}";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SDKROOT = iphoneos;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};
@@ -855,7 +871,7 @@
 				PRODUCT_NAME = SwiftCSV;
 				SDKROOT = macosx;
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -882,7 +898,7 @@
 				PRODUCT_NAME = SwiftCSV;
 				SDKROOT = macosx;
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};
@@ -901,7 +917,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "naoty.SwiftCSV.SwiftCSV-OSXTests";
 				PRODUCT_NAME = SwiftCSVTests;
 				SDKROOT = macosx;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -921,7 +937,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "naoty.SwiftCSV.SwiftCSV-OSXTests";
 				PRODUCT_NAME = SwiftCSVTests;
 				SDKROOT = macosx;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};
@@ -944,7 +960,7 @@
 				PRODUCT_NAME = SwiftCSV;
 				SDKROOT = appletvos;
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 				TARGETED_DEVICE_FAMILY = 3;
 				TVOS_DEPLOYMENT_TARGET = 9.2;
 			};
@@ -970,7 +986,7 @@
 				PRODUCT_NAME = SwiftCSV;
 				SDKROOT = appletvos;
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 				TARGETED_DEVICE_FAMILY = 3;
 				TVOS_DEPLOYMENT_TARGET = 9.2;
 			};
@@ -988,7 +1004,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "naoty.SwiftCSV.SwiftCSV-tvOSTests";
 				PRODUCT_NAME = SwiftCSVTests;
 				SDKROOT = appletvos;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 				TVOS_DEPLOYMENT_TARGET = 9.2;
 			};
 			name = Debug;
@@ -1006,7 +1022,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "naoty.SwiftCSV.SwiftCSV-tvOSTests";
 				PRODUCT_NAME = SwiftCSVTests;
 				SDKROOT = appletvos;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 				TVOS_DEPLOYMENT_TARGET = 9.2;
 			};
 			name = Release;
@@ -1031,7 +1047,7 @@
 				PRODUCT_NAME = SwiftCSV;
 				SDKROOT = watchos;
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 				TARGETED_DEVICE_FAMILY = 4;
 				WATCHOS_DEPLOYMENT_TARGET = 2.2;
 			};
@@ -1058,7 +1074,7 @@
 				PRODUCT_NAME = SwiftCSV;
 				SDKROOT = watchos;
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 				TARGETED_DEVICE_FAMILY = 4;
 				WATCHOS_DEPLOYMENT_TARGET = 2.2;
 			};
diff --git a/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV OSX.xcscheme b/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV OSX.xcscheme
index 9a6d28b..24219c8 100644
--- a/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV OSX.xcscheme	
+++ b/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV OSX.xcscheme	
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0800"
+   LastUpgradeVersion = "0940"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV tvOS.xcscheme b/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV tvOS.xcscheme
index 96567d5..aa09e27 100644
--- a/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV tvOS.xcscheme	
+++ b/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV tvOS.xcscheme	
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0800"
+   LastUpgradeVersion = "0940"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV watchOS.xcscheme b/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV watchOS.xcscheme
index b1b388c..7573a1d 100644
--- a/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV watchOS.xcscheme	
+++ b/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV watchOS.xcscheme	
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0800"
+   LastUpgradeVersion = "0940"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV.xcscheme b/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV.xcscheme
index 76e49a2..7330415 100644
--- a/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV.xcscheme
+++ b/SwiftCSV.xcodeproj/xcshareddata/xcschemes/SwiftCSV.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0800"
+   LastUpgradeVersion = "0940"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/SwiftCSV/CSV.swift b/SwiftCSV/CSV.swift
index ae95ff7..c66b931 100644
--- a/SwiftCSV/CSV.swift
+++ b/SwiftCSV/CSV.swift
@@ -9,9 +9,9 @@
 import Foundation
 
 open class CSV {
-    static fileprivate let comma: Character = ","
+    static public let comma: Character = ","
     
-    open let header: [String]
+    public let header: [String]
 
     lazy var _namedView: NamedView = {
 
diff --git a/SwiftCSV/ParsingState.swift b/SwiftCSV/ParsingState.swift
index 298514c..a2bb6f8 100644
--- a/SwiftCSV/ParsingState.swift
+++ b/SwiftCSV/ParsingState.swift
@@ -6,12 +6,6 @@
 //  Copyright © 2016 Naoto Kaneko. All rights reserved.
 //
 
-fileprivate extension Character {
-    var isNewline: Bool {
-        return self == "\n" || self == "\r\n"
-    }
-}
-
 /// State machine of parsing CSV contents character by character.
 struct ParsingState {
 
diff --git a/SwiftCSV/String+Lines.swift b/SwiftCSV/String+Lines.swift
index 04604e3..d824d3f 100644
--- a/SwiftCSV/String+Lines.swift
+++ b/SwiftCSV/String+Lines.swift
@@ -7,12 +7,17 @@
 //
 
 extension String {
-    var firstLine: String {
+    internal var firstLine: String {
         var current = startIndex
-        let chars = characters
-        while current < endIndex && chars[current] != "\r\n" && chars[current] != "\n" && chars[current] != "\r" {
+        while current < endIndex && self[current].isNewline == false {
             current = self.index(after: current)
         }
-        return substring(to: current)
+        return String(self[..<current])
+    }
+}
+
+extension Character {
+    internal var isNewline: Bool {
+        return self == "\n" || self == "\r\n" || self == "\r"
     }
 }