When I was living in Amsterdam, I participated in plenty of Appsterdam events. Things like the weekly Meeten en Drinken. I even helped lead a class in Swift. One of the events I liked the most was called Peer Lab, organized every Saturday morning by Samuel Goodwin.
The idea of Peer Lab is pretty simple, but also somewhat profound: developers gather in a physical space to work on things. If someone has a question, they ask the group. If you can help, you offer assistance. The goal is to foster a collaborative learning environment where everyone feels fulfilled.
Samuel held Peer Lab on Saturday mornings to dissuade recruiters from attending. The café where we met had wifi and good coffee, which is all you really need when you're trying to get something accomplished on a Saturday morning.