I am using google+ sign in my app using the Google Plus SDK. When the user taps on the sign in button the user gets redirected to safari. (Standard Process).
However
To resolve this problem you can use Google libs. It's has a G+ SDK inside and has GTMAuth2ControllerTouch, which provides you sign into all Google service. Look here how to get this library and here is an example how to use it. It's very easy. Also you can find some videos on YouTube, which describes how to install this library.
You can use this library with Google+ SDK, but you need to do some work to merge this 2 APIs.