Add gitignore file.

Author: Calvin

.gitignore

@@ -0,0 +1,52 @@
+# Xcode
+#
+build/
+Build/
+*.pbxuser
+!default.pbxuser
+*.mode1v3
+!default.mode1v3
+*.mode2v3
+!default.mode2v3
+*.perspectivev3
+!default.perspectivev3
+xcuserdata
+*.xccheckout
+*.moved-aside
+DerivedData
+*.hmap
+*.ipa
+*.xcuserstate
+
+timeline.xctimeline
+
+# 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/
+
+# Carthage
+#
+# Add this line if you want to avoid checking in source code from Carthage dependencies.
+# Carthage/Checkouts
+
+Carthage/Build
+
+
+# Various
+
+.DS_Store
+
+
+# Linux
+
+*.swp
+*.swo
+
+# Swift Package Manager
+
+.build/
+Packages/