Fix warning and update project setting

Demo/Kingfisher-Demo.xcodeproj/project.pbxproj

@@ -600,7 +600,7 @@
 					D1ED2D0A1AD2CFA600CFC3EB = {
 						CreatedOnToolsVersion = 6.2;
 						DevelopmentTeam = A4YJ9MRZ66;
-						LastSwiftMigration = 0900;
+						LastSwiftMigration = 1200;
 					};
 					D1F7609423098F62000C5269 = {
 						CreatedOnToolsVersion = 11.0;
@@ -1038,7 +1038,7 @@
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				TVOS_DEPLOYMENT_TARGET = 10.0;
 				WATCHOS_DEPLOYMENT_TARGET = 3.0;
@@ -1090,7 +1090,7 @@
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				TVOS_DEPLOYMENT_TARGET = 10.0;
 				VALIDATE_PRODUCT = YES;
@@ -1155,7 +1155,6 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "com.onevcat.Kingfisher-SwiftUI-Demo";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
-				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Debug;
@@ -1182,7 +1181,6 @@
 				MTL_FAST_MATH = YES;
 				PRODUCT_BUNDLE_IDENTIFIER = "com.onevcat.Kingfisher-SwiftUI-Demo";
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Release;

Kingfisher.xcodeproj/project.pbxproj

@@ -749,7 +749,7 @@
 			isa = PBXProject;
 			attributes = {
 				LastSwiftUpdateCheck = 0720;
-				LastUpgradeCheck = 1100;
+				LastUpgradeCheck = 1200;
 				ORGANIZATIONNAME = "Wei Wang";
 				TargetAttributes = {
 					D1ED2D341AD2D09F00CFC3EB = {
@@ -950,6 +950,7 @@
 				CLANG_WARN_OBJC_IMPLICIT_RETAIN_SELF = YES;
 				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_QUOTED_INCLUDE_IN_FRAMEWORK_HEADER = YES;
 				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
 				CLANG_WARN_STRICT_PROTOTYPES = YES;
 				CLANG_WARN_SUSPICIOUS_MOVE = YES;
@@ -984,7 +985,7 @@
 				SUPPORTED_PLATFORMS = "watchsimulator iphonesimulator appletvsimulator watchos appletvos iphoneos macosx";
 				SWIFT_INSTALL_OBJC_HEADER = NO;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2,3,4";
 				TVOS_DEPLOYMENT_TARGET = 10.0;
 				WATCHOS_DEPLOYMENT_TARGET = 3.0;
@@ -1014,6 +1015,7 @@
 				CLANG_WARN_OBJC_IMPLICIT_RETAIN_SELF = YES;
 				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_QUOTED_INCLUDE_IN_FRAMEWORK_HEADER = YES;
 				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
 				CLANG_WARN_STRICT_PROTOTYPES = YES;
 				CLANG_WARN_SUSPICIOUS_MOVE = YES;
@@ -1040,7 +1042,7 @@
 				SUPPORTED_PLATFORMS = "watchsimulator iphonesimulator appletvsimulator watchos appletvos iphoneos macosx";
 				SWIFT_INSTALL_OBJC_HEADER = NO;
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2,3,4";
 				TVOS_DEPLOYMENT_TARGET = 10.0;
 				WATCHOS_DEPLOYMENT_TARGET = 3.0;

Kingfisher.xcodeproj/xcshareddata/xcschemes/Kingfisher.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1110"
+   LastUpgradeVersion = "1200"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
@@ -28,15 +28,6 @@
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
       shouldUseLaunchSchemeArgsEnv = "YES"
       codeCoverageEnabled = "YES">
-      <MacroExpansion>
-         <BuildableReference
-            BuildableIdentifier = "primary"
-            BlueprintIdentifier = "D1ED2D341AD2D09F00CFC3EB"
-            BuildableName = "Kingfisher.framework"
-            BlueprintName = "Kingfisher"
-            ReferencedContainer = "container:Kingfisher.xcodeproj">
-         </BuildableReference>
-      </MacroExpansion>
       <Testables>
          <TestableReference
             skipped = "NO"

Kingfisher.xcodeproj/xcshareddata/xcschemes/KingfisherSwiftUI.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1110"
+   LastUpgradeVersion = "1200"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

Sources/General/KingfisherManager.swift

@@ -206,7 +206,7 @@ public class KingfisherManager {
         downloadTaskUpdated: DownloadTaskUpdatedBlock? = nil,
         completionHandler: ((Result<RetrieveImageResult, KingfisherError>) -> Void)?) -> DownloadTask?
     {
-        var retrievingContext = RetrievingContext(options: options, originalSource: source)
+        let retrievingContext = RetrievingContext(options: options, originalSource: source)
         var retryContext: RetryContext?
 
         func startNewRetrieveTask(