This service is invalid - iPhone

This error that I was presented by Xcode while trying to run my App in iPhone, led me wildly think that my developer certificate has been either revoked or has past its life.
          But after googling found a result which asked me to restart my iPhone and after this I successfully got rid of the "This service is invalid " error message but was faced with another error message "an unknown error occurred". Then I tried by disconnecting the phone from Mac and restarted the phone. 


And this worked and my  app was installed in the phone.