Add additional file types for extensions

This adds a few Xcode file types for some extensions that were
previously not included. Before this change if you had a file reference
in a generated project with one of these extensions Xcode would insert
it into the project file after opening it the first time.

Author: keith

lib/xcodeproj/constants.rb

@@ -81,26 +81,32 @@ module Constants
     # @return [Hash] The known file types corresponding to each extension.
     #
     FILE_TYPES_BY_EXTENSION = {
-      'a'           => 'archive.ar',
-      'app'         => 'wrapper.application',
-      'bundle'      => 'wrapper.plug-in',
-      'dylib'       => 'compiled.mach-o.dylib',
-      'framework'   => 'wrapper.framework',
-      'h'           => 'sourcecode.c.h',
-      'm'           => 'sourcecode.c.objc',
-      'markdown'    => 'text',
-      'mdimporter'  => 'wrapper.cfbundle',
-      'octest'      => 'wrapper.cfbundle',
-      'pch'         => 'sourcecode.c.h',
-      'plist'       => 'text.plist.xml',
-      'sh'          => 'text.script.sh',
-      'swift'       => 'sourcecode.swift',
-      'xcassets'    => 'folder.assetcatalog',
-      'xcconfig'    => 'text.xcconfig',
-      'xcdatamodel' => 'wrapper.xcdatamodel',
-      'xcodeproj'   => 'wrapper.pb-project',
-      'xctest'      => 'wrapper.cfbundle',
-      'xib'         => 'file.xib',
+      'a'            => 'archive.ar',
+      'apns'         => 'text',
+      'app'          => 'wrapper.application',
+      'appex'        => 'wrapper.app-extension',
+      'bundle'       => 'wrapper.plug-in',
+      'dylib'        => 'compiled.mach-o.dylib',
+      'entitlements' => 'text.plist.entitlements',
+      'framework'    => 'wrapper.framework',
+      'h'            => 'sourcecode.c.h',
+      'm'            => 'sourcecode.c.objc',
+      'markdown'     => 'text',
+      'mdimporter'   => 'wrapper.cfbundle',
+      'octest'       => 'wrapper.cfbundle',
+      'pch'          => 'sourcecode.c.h',
+      'plist'        => 'text.plist.xml',
+      'sh'           => 'text.script.sh',
+      'sks'          => 'file.sks',
+      'storyboard'   => 'file.storyboard',
+      'strings'      => 'text.plist.strings',
+      'swift'        => 'sourcecode.swift',
+      'xcassets'     => 'folder.assetcatalog',
+      'xcconfig'     => 'text.xcconfig',
+      'xcdatamodel'  => 'wrapper.xcdatamodel',
+      'xcodeproj'    => 'wrapper.pb-project',
+      'xctest'       => 'wrapper.cfbundle',
+      'xib'          => 'file.xib',
     }.freeze
 
     # @return [Hash] The uniform type identifier of various product types.