'It creates an instance of one of the supported mobile platforms (i.e. iOS, Android) by regex comparison
of user-agent.
Parameters:
user_agent: user_agent of mobile app
Returns:
instance of one of the supported mobile platforms (i.e. iOS, Android)'

@classmethod
def get_instance(cls, user_agent):

    for subclass in PLATFORM_CLASSES.values():
        instance = subclass.get_user_app_platform(user_agent, subclass.USER_AGENT_REGEX)
        if instance:
            return instance
