diff --git a/NSAttributedStringFormat.xcodeproj/project.pbxproj b/NSAttributedStringFormat.xcodeproj/project.pbxproj
index db476d2..b921cf5 100644
--- a/NSAttributedStringFormat.xcodeproj/project.pbxproj
+++ b/NSAttributedStringFormat.xcodeproj/project.pbxproj
@@ -8,9 +8,9 @@
 
 /* Begin PBXBuildFile section */
 		279E6DC21BB8855B0043DDC9 /* NSAttributedStringFormat.h in Headers */ = {isa = PBXBuildFile; fileRef = 279E6DC11BB8855B0043DDC9 /* NSAttributedStringFormat.h */; settings = {ATTRIBUTES = (Public, ); }; };
-		279E6DC91BB8855B0043DDC9 /* NSAttributedStringFormat.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 279E6DBE1BB8855B0043DDC9 /* NSAttributedStringFormat.framework */; settings = {ASSET_TAGS = (); }; };
-		279E6DD91BB8857A0043DDC9 /* NSAttributedString+CCLFormatTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 279E6DD81BB8857A0043DDC9 /* NSAttributedString+CCLFormatTests.m */; settings = {ASSET_TAGS = (); }; };
-		279E6DDB1BB885AF0043DDC9 /* NSAttributedString+CCLFormat.m in Sources */ = {isa = PBXBuildFile; fileRef = 279E6DDA1BB885AF0043DDC9 /* NSAttributedString+CCLFormat.m */; settings = {ASSET_TAGS = (); }; };
+		279E6DC91BB8855B0043DDC9 /* NSAttributedStringFormat.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 279E6DBE1BB8855B0043DDC9 /* NSAttributedStringFormat.framework */; };
+		279E6DD91BB8857A0043DDC9 /* NSAttributedString+CCLFormatTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 279E6DD81BB8857A0043DDC9 /* NSAttributedString+CCLFormatTests.m */; };
+		279E6DDB1BB885AF0043DDC9 /* NSAttributedString+CCLFormat.m in Sources */ = {isa = PBXBuildFile; fileRef = 279E6DDA1BB885AF0043DDC9 /* NSAttributedString+CCLFormat.m */; };
 		279E6DDD1BB885BF0043DDC9 /* NSAttributedString+CCLFormat.h in Headers */ = {isa = PBXBuildFile; fileRef = 279E6DDC1BB885BF0043DDC9 /* NSAttributedString+CCLFormat.h */; settings = {ATTRIBUTES = (Public, ); }; };
 /* End PBXBuildFile section */
 
@@ -165,11 +165,12 @@
 		279E6DB51BB8855B0043DDC9 /* Project object */ = {
 			isa = PBXProject;
 			attributes = {
-				LastUpgradeCheck = 0700;
+				LastUpgradeCheck = 0900;
 				ORGANIZATIONNAME = Cocode;
 				TargetAttributes = {
 					279E6DBD1BB8855B0043DDC9 = {
 						CreatedOnToolsVersion = 7.0;
+						LastSwiftMigration = 0830;
 					};
 					279E6DC71BB8855B0043DDC9 = {
 						CreatedOnToolsVersion = 7.0;
@@ -247,13 +248,21 @@
 				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;
 				COPY_PHASE_STRIP = NO;
@@ -275,10 +284,9 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
+				IPHONEOS_DEPLOYMENT_TARGET = 10.3;
 				MACOSX_DEPLOYMENT_TARGET = 10.10;
 				MTL_ENABLE_DEBUG_INFO = YES;
-				ONLY_ACTIVE_ARCH = YES;
-				SDKROOT = macosx;
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
 			};
@@ -292,13 +300,21 @@
 				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;
 				COPY_PHASE_STRIP = NO;
@@ -314,9 +330,9 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
+				IPHONEOS_DEPLOYMENT_TARGET = 10.3;
 				MACOSX_DEPLOYMENT_TARGET = 10.10;
 				MTL_ENABLE_DEBUG_INFO = NO;
-				SDKROOT = macosx;
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
 			};
@@ -326,6 +342,8 @@
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 279E6DE21BB8A4CB0043DDC9 /* UniversalFramework_Framework.xcconfig */;
 			buildSettings = {
+				ARCHS = "$(ARCHS_STANDARD_32_64_BIT)";
+				CLANG_ENABLE_MODULES = YES;
 				COMBINE_HIDPI_IMAGES = YES;
 				DEFINES_MODULE = YES;
 				DYLIB_COMPATIBILITY_VERSION = 1;
@@ -338,6 +356,8 @@
 				PRODUCT_BUNDLE_IDENTIFIER = org.cocode.NSAttributedStringFormat;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
+				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_VERSION = 3.0;
 			};
 			name = Debug;
 		};
@@ -345,6 +365,8 @@
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 279E6DE21BB8A4CB0043DDC9 /* UniversalFramework_Framework.xcconfig */;
 			buildSettings = {
+				ARCHS = "$(ARCHS_STANDARD_32_64_BIT)";
+				CLANG_ENABLE_MODULES = YES;
 				COMBINE_HIDPI_IMAGES = YES;
 				DEFINES_MODULE = YES;
 				DYLIB_COMPATIBILITY_VERSION = 1;
@@ -357,6 +379,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = org.cocode.NSAttributedStringFormat;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
+				SWIFT_VERSION = 3.0;
 			};
 			name = Release;
 		};
diff --git a/NSAttributedStringFormat.xcodeproj/xcshareddata/xcschemes/NSAttributedStringFormat.xcscheme b/NSAttributedStringFormat.xcodeproj/xcshareddata/xcschemes/NSAttributedStringFormat.xcscheme
index f9363f1..a18dcec 100644
--- a/NSAttributedStringFormat.xcodeproj/xcshareddata/xcschemes/NSAttributedStringFormat.xcscheme
+++ b/NSAttributedStringFormat.xcodeproj/xcshareddata/xcschemes/NSAttributedStringFormat.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0700"
+   LastUpgradeVersion = "0900"
    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/NSAttributedStringFormat/NSAttributedString+CCLFormat.h b/NSAttributedStringFormat/NSAttributedString+CCLFormat.h
index 71779f6..5341b05 100644
--- a/NSAttributedStringFormat/NSAttributedString+CCLFormat.h
+++ b/NSAttributedStringFormat/NSAttributedString+CCLFormat.h
@@ -1,5 +1,7 @@
 #import <Foundation/Foundation.h>
 
+NS_ASSUME_NONNULL_BEGIN
+
 /** Attributed string extension for creating attributed strings from a format string. */
 @interface NSAttributedString (CCLFormat)
 
@@ -16,7 +18,7 @@
  @param arguments list of arguments to substitute into format.
  @return An attributed string created by using format as a template into which the remaining argument values are substituted.
  */
-+ (instancetype)attributedStringWithAttributes:(NSDictionary *)attributes format:(NSString *)format, ... NS_FORMAT_FUNCTION(2,3);
++ (instancetype)attributedStringWithAttributes:(nullable id)attributes format:(NSString *)format, ... NS_FORMAT_FUNCTION(2,3);
 
 /** Returns an attributed string created by using a given format string as a template into which the remaining argument values are substituted.
  @param format A format string. This value must not be nil.
@@ -31,7 +33,7 @@
  @param arguments list of arguments to substitute into format.
  @return An attributed string created by using format as a template into which the remaining argument values are substituted.
  */
-+ (instancetype)attributedStringWithAttributes:(NSDictionary *)attributes format:(NSString *)format arguments:(va_list)arguments NS_FORMAT_FUNCTION(2,0);
++ (instancetype)attributedStringWithAttributes:(nullable id)attributes format:(NSString *)format arguments:(va_list)arguments NS_FORMAT_FUNCTION(2,0);
 
 /** Returns an attributed string created by using a given format string as a template into which the remaining argument values are substituted.
  @param format A format string. This value must not be nil.
@@ -46,7 +48,7 @@
  @param ... A comma-separated list of arguments to substitute into format.
  @return An attributed string created by using format as a template into which the remaining argument values are substituted.
  */
-- (instancetype)initWithAttributes:(NSDictionary *)attributes format:(NSString *)format, ... NS_FORMAT_FUNCTION(2,3);
+- (instancetype)initWithAttributes:(nullable id)attributes format:(NSString *)format, ... NS_FORMAT_FUNCTION(2,3);
 
 /** Returns an attributed string created by using a given format string as a template into which the remaining argument values are substituted.
  @param format A format string. This value must not be nil.
@@ -61,7 +63,9 @@
  @param arguments list of arguments to substitute into format.
  @return An attributed string created by using format as a template into which the remaining argument values are substituted.
  */
-- (instancetype)initWithAttributes:(NSDictionary *)attributes format:(NSString *)format arguments:(va_list)arguments NS_FORMAT_FUNCTION(2,0);
+- (instancetype)initWithAttributes:(nullable id)attributes format:(NSString *)format arguments:(va_list)arguments NS_FORMAT_FUNCTION(2,0);
 
 
 @end
+
+NS_ASSUME_NONNULL_END