TStepProject is one solution that allows you to easily find your friends based on your geolocation. It is powered by Telegram Messenger using its API https://core.telegram.org/api
Beware of bugs and problems when using this source files, since it is in development.
First of all, take a look at src/main/java/org/telegram/messenger/BuildVars.java and fill it with correct values. Import the root folder into your IDE (tested on Android Studio), then run project.
TStepProject uses Telegram as its source base, and you can see their official open source project here.
For informations about their API, Protocol and documentation, please visit:
Telegram API manuals: http://core.telegram.org/api
MTproto protocol manuals: http://core.telegram.org/mtproto
Translations: https://www.transifex.com/projects/p/telegram/
##Creating your Telegram Application
Please visit https://core.telegram.org/api/obtaining_api_id
Lastly, but not least, TStepProject extends Telegram in its license using the GNU GPL v. 2 or later, so please be aware of that, regarding copying, modifying and (re)destributing the application.