How to prevent being pick pocketed?

I know it sound like its my fault and it kinda is, but i got my iphone stolen from me at a modestep gig in London it totally ruined the otherwise awesome night and i'm still pissed off by it. It got pick pocketed from me whilst in the crowd of raving people so i was already being touched from like every angle haha.
Obviously i should not put it on show which i did to take pictures and i shouldn't even bring it in seeming as the phone stealing rate in London is insane. How can i prevent from this happening again?

Keep it in a zipped front pocket, or leave it at home.