Add Xcode support.

Objective-C.gitignore

@@ -1,21 +1,3 @@
-# Xcode
-build/
-*.pbxuser
-!default.pbxuser
-*.mode1v3
-!default.mode1v3
-*.mode2v3
-!default.mode2v3
-*.perspectivev3
-!default.perspectivev3
-xcuserdata
-*.xccheckout
-profile
-*.moved-aside
-DerivedData
-*.hmap
-*.ipa
-
 # CocoaPods
 #
 # We recommend against adding the Pods directory to your .gitignore. However