There are plenty of co-working places, but some are also incubator centers. I can sort them with most related with mobile apps to least. From my point of view. (I'm an ios developer in ist for more than 3 years)
They are dedicated to startups and also games. Many mobile games were born there you can take a look their portfolio. And yes great event center they organize game jams, hackathons etc.
I love ambience of kolektif house and the event's are fertile for entrepreneurs.
KWorks was founded by Koc University with aim to improve and connect startup habitat in Istanbul.
I've been there for 2 days and I think their ambience is more like a expensive restaurant. Lovely, but little expensive can be used for important meetings though.
You can take look at other coworking places. But in my experience starters hub is the best place to meet mobile app developers and entrepreneurs even VC's in istanbul.