When a screen appears you call three APIs in parallel, profile, feed, and notifications, and you have to render the UI once when all of them finish. How would you build that with GCD?
Create a DispatchGroup, enter before each request, leave when its response arrives, and combine the three in notify(queue: .main) to render. Don't block with wait(), and collect results in a spot protected by a serial queue or a lock.
ConcurrencyMultiple choiceAdvanced
Which of the following statements about structured concurrency (async let, TaskGroup) are…
#async-let #taskgroup
ConcurrencyShort answerBasics
You have independent pieces of work A, B, and C. C must run only after both A and B have…
#dispatchgroup #async-let
ConcurrencyShort answerBasics
A banking app's home screen has to fetch independent account, card, and notification data…
#async-let #taskgroup
ConcurrencyMultiple choiceBasics
Which of the following statements about DispatchSemaphore and mutexes (NSLock, Mutex) are…
#semaphore