I don't remember most of the questions. I do remember being asked about basic things regarding optionals, about how it handles exceptions (Swift 2 had been announced like a week before the interview and changed how it did exceptions entirely to try-catch blocks, and I answered that, but then they were like "okay, how about in Swift 1", and I blanked, even though I put them into the toy app I was doing).
Another was something like "In Swift, what are higher-order functions?", which I somehow only heard that term a couple of times before and didn't have fresh in my head, despite using higher-order functions in plenty of programming languages (C#, Python, Ruby, even in Objective-C). That one was a case of knowing the concept but not the term.
I believe those two questions were the main ones that lead to the rejection, because I stumbled and didn't come across as confident there, but was otherwise pretty calm and answered the other questions well. I was in and out of there in 45 minutes, talked to one person who quizzed me on the names of UI objects on a given screen, and then the pop-quiz-style interview with two other people.
I also stupidly didn't show them the app I had partially built in Swift, even though I brought an iPad with me. I think I even mentioned it, and they're like "You have it here?" and I said "It's not finished..." and they just started asking me more questions. It was a working puzzle game, but some of the logic for clearing matches was wonky at the time and was visibly broken so I was hesitant to show it.