Use 'Mac developer' CodeSign identity

Swifter.xcodeproj/project.pbxproj

@@ -527,7 +527,7 @@
 		7AE894011C0512C400A29F63 /* Debug */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
-				CODE_SIGN_IDENTITY = "-";
+				CODE_SIGN_IDENTITY = "Mac Developer";
 				COMBINE_HIDPI_IMAGES = YES;
 				CURRENT_PROJECT_VERSION = 1;
 				DEBUG_INFORMATION_FORMAT = dwarf;
@@ -554,7 +554,7 @@
 		7AE894021C0512C400A29F63 /* Release */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
-				CODE_SIGN_IDENTITY = "-";
+				CODE_SIGN_IDENTITY = "Mac Developer";
 				COMBINE_HIDPI_IMAGES = YES;
 				COPY_PHASE_STRIP = NO;
 				CURRENT_PROJECT_VERSION = 1;