[objc] use Autolayout

http://www.raywenderlich.com/ko/21139/ios-6%EC%97%90%EC%84%9C-%EC%98%A4%ED%86%A0-%EB%A0%88%EC%9D%B4%EC%95%84%EC%9B%83-%EC%8B%9C%EC%9E%91%ED%95%98%EA%B8%B0-%ED%8C%8C%ED%8A%B8-1-1