change xcrun developer path
1 . sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer
2. Open terminal and copy paste the following URL.
svn checkout http://google-api-objectivec-client.googlecode.com/svn/trunk/ google-api-objectivec-client-read-only
For latest Library :
https://code.google.com/p/google-api-objectivec-client/source/checkout