Update swift.gitignore

Added explanation for most settings.

Swift.gitignore

@@ -1,26 +1,47 @@
-# Xcode
-#
-build/
-*.pbxuser
-!default.pbxuser
-*.mode1v3
-!default.mode1v3
-*.mode2v3
-!default.mode2v3
-*.perspectivev3
-!default.perspectivev3
-xcuserdata
-*.xccheckout
-*.moved-aside
-DerivedData
-*.hmap
-*.ipa
-*.xcuserstate
+## OS X temporary files that should never be committed
+.DS_Store
+*.swp
+*.lock
+profile
 
-# 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/
+## Private project folders
+#Graphics/
+#Ideas/
+
+### Defaults for Xcode 6
+
+## Folders
+build/
+DerivedData/
+
+## Xcode private settings (window sizes, bookmarks, breakpoints, custom executables, smart groups)
+*.pbxuser
+*.mode1v3
+*.mode2v3
+*.perspectivev3
+!default.pbxuser
+!default.mode1v3
+!default.mode2v3
+!default.perspectivev3
+
+### Options (NB: hierarhically dependent)
+## 1- throw away ALL personal settings (including custom schemes!
+xcuserdata
+## 2- get rid of ALL personal settings, but KEEP SOME OF THEM
+#xcuserdata/**/*
+## 3- keep personal schemes
+#!xcuserdata/**/xcschemes/*
+
+## Allegedly, if you manually "deprecate" your classes, they get moved here.
+*.moved-aside
+
+## Binary file
+*.ipa
+
+# Playground states
+*.xctimeline
+
+## Unknown settings... Please define
+*.hmap
+*.xccheckout
+*.xcuserstate