I have moved this over to the Tech Interview Cheat Sheet Repo and has been expanded and even has code challenges you can run and practice against!
The below is just for some preservation for those who stumble across here, but is no longer kept up to date.
This list is meant to be both a quick guide and reference for further research into these topics. It's basically a summary of that comp sci course you never took or forgot about, so there's no way it can cover everything in depth.
General iOS, CS questions and interview prep resources.
iOS Interview Questions for Senior Developers (useful even if you're not senior yet)
Modern Cocoa development involves a lot of asynchronous programming using blocks and NSOperations. A lot of APIs are exposing blocks and they are more natural to write a lot of logic, so we'll only focus on block-based APIs.
Block-based APIs are hard to use when number of operations grows and dependencies between them become more complicated. In this paper I introduce asynchronous semantics and Promise type to Swift language (borrowing ideas from design of throw-try-catch and optionals). Functions can opt-in to become async, programmer can compose complex logic involving asynchronous operations while compiler produces necessary closures to implement that logic. This proposal does not propose new runtime model, nor "actors" or "coroutines".
