Swift wasn't initially open-source either. I remember this because I was like, nope fuck that shit until it's open source so I never touched Swift until Swift 2.0 when they open sourced it.

(Actually IIRC I started learning it when they promised to open source it later that same year. So the actual moment of open-sourcing might have been slightly later.)

Sure, it was a secret project at Apple and a surprise even to a lot of employees.

I meant when they actually opened the gates. My recollection is that they were overwhelmed by the feedback and community building.