The referee was the same guy that got panned for not giving Barca penalties against Milan last year,so of course he gave them one today to make up for it. Also, all Swedes love Barcelona, so he was probably a Barca fan. City would have won this game if it was not for the referee.
On the pitch yeah, after replays, not. People see the replay rewinded a million times in slow-mo, and then blame the ref if it's not correct by a millimeter, especially when favoring Barca.