[.gitignore] Update .gitignore.

.gitignore

@@ -1,6 +1,32 @@
-# Exclude OS X folder attributes
+# OS X
+#
 .DS_Store
-
-# Exclude user-specific XCode files
-*.xcworkspace
+
+# Xcode
+#
+build/
+*.pbxuser
+!default.pbxuser
+*.mode1v3
+!default.mode1v3
+*.mode2v3
+!default.mode2v3
+*.perspectivev3
+!default.perspectivev3
 xcuserdata
+*.xccheckout
+*.moved-aside
+DerivedData
+*.hmap
+*.ipa
+*.xcuserstate
+*.gcno
+*.gcda
+
+# CocoaPods
+#
+# We recommend against adding the Pods directory to your .gitignore. However
+# you should judge for yourself, the pros and cons are mentioned at:
+# http://guides.cocoapods.org/using/using-cocoapods.html#should-i-ignore-the-pods-directory-in-source-control
+#
+Pods/