This is a companion discussion topic for the original entry at https://www.raywenderlich.com/9461083-ios-concurrency-with-gcd-and-operations/lessons/3
This is a companion discussion topic for the original entry at https://www.raywenderlich.com/9461083-ios-concurrency-with-gcd-and-operations/lessons/3
sync
you want to prevent other tasks from running while this task is running
Thank you. Please correct it in the video
sorry, it’s been a while, and it’s easy to get confused …
that code dispatches to a serial queue, so tasks on internalQueue run in the order they arrive. If you dispatch a write task, followed by a read task, the read task must wait its turn on internalQueue.
whether you dispatch sync or async doesn’t affect the fact that the tasks on internalQueue run serially.
sync or async affects the queue you’re dispatching from — whether or not it waits for the task to finish before continuing. You want to wait for a read task to complete before you continue, because you need the value it’s reading. You don’t need to wait for a write task, because it’s not returning any value.
Where did you find that slide? I can’t find it in the files for any of this part’s videos.