Concurrency using Actors | Swift 5.5 | Async/Await | Data Race

Concurrency has always been a pain point for developers and Swift 5.5 has introduced some really cool APIs to make it easy.
In this video, I’ve discussed Actors in detail. For explaining its usage, I took an example having Data Race (seat booking), fixed it using conventional ways (Dispatch Barrier), and rewrote the logic using Actor (for showing the difference that how easy it gets with Actor).
Along the way, I’ve also discussed (and used) Async/Await and Main Actors (for updating the UI from background thread).
Please have a look.

[@raymondcordero9718]

Awesome video. Thanks for sharing your knowledge. Helps a lot

[@iampuco445]

You have great didactic abilities … bravo from 🇨🇭

[@malleshaholeyache4464]

Awesome awesome explanation brother 🤩🤩. Thank you so much for your all videos 😍

[@govind20246]

Actor concept is Nice , it's really interesting, compare to existing techniques.

[@kishangupta863]

Very well explained. Keep up the good work.

[@iCode_Happy_Coding]

Thanks for the kind words 🙂

[@puneetpal1466]

Thank you for nice content.

[@rooo2000]

well done very nice explanation 👍

[@user-fd4gd8rf3z]

Thank you for awesome video !!!

[@rahuljamba5846]

Thanks Palav

[@apoorvamishra2047]

Thanks for the nice content

[@sanilabraham9209]

Thankssssss....😍😍😍

[@yogeshrathore919]

Very nice explanation.

[@iCode_Happy_Coding]

Thanks Yogesh 🙂

[@user-bb1ke2sw1j]

superbb

[@vm5lbj23]

Learnt something new today. Thank you. What I am more curious about is how the actor is working internally?

[@pawanmanjani1298]

Superb keep posting💪

[@iCode_Happy_Coding]

Sure 🙂

[@madhavkure3361]

Very nice sir. thanks

[@mazedar_tv]

Why writing Task in DispatchQueue ? Also 5:31 why we want to halt the main. thread via using `sync` instead of `async` , is it just to return value?

[@benjaminludwig9457]

Hey, thanks so much! Why are the queues at the end still needed? Or if they aren't needed, why are you still using them?

[@sheldon94666]

Interesting trade off. The barrier was neat in the old Flight class. Now the burden to make it properly called, the caller are forced to call with async await.

[@akshaykumar-qj2kx]

Great Job 👏

[@iCode_Happy_Coding]

Thanks Akshay 🙂

[@shiwivishu4434]

Hey pallev,
Thanks for this great video. now I have a clear concept of Actor. I would really appreciate if you can come up with one video of Closures. thanks

[@RAHULSHARMA-iu1xq]

Nice explanation 👍

[@iCode_Happy_Coding]

Thanks 🙂

[@manjeetchoudhary5860]

🎉🎉🎉🎉❤

[@pramanshugoel6606]

Hey pallev,
Thanks for the video.
Have one question why you used sync on both operations with barrier.I think same could be achieved without using barrier on sync operation (as they already in sync)or async operation with barrier?

[@tusharlama6085]

Use sync function for read to block current thread, while using async function with barrier flag for write to return to current queue. This is good for when multiple reads is preferred when there is no write.

[@vineetsingh8201]

👍

[@Purnao6151]

I learnt the latest topic. Thanks for sharing.

[@saurabhsierra9195]

Impressive ....once again.👏👏👏

[@marlonvonansale6457]

thanks for the video keep up the good work :)

[@abhishekboosarapu6071]

Hi Pallav,
Great fan of yours. In a couple of interviews, I faced this question. "How do you convert struct to a class? or atleast give some functionalities of class to struct." I searched a lot through web but couldn't find any answer. Could you please help me with this.

[@w0mblemania]

TBH, it's not a very good question from the interviewer.
I guess they could be trying to make you think, but still, not a useful question.
The only good response I would give is "what, exactly, do you want your class to do"?
And then explain the differences between structs and classes, and why you don't actually want to be "converting" structs to classes.

[@dhav7634]

Great tutorial. I observed that even when I did not create add keyword "MainActor" and just called the updateLabel method from my Task block, I did NOT get a crash and the setting up the break point inside updateLabel showed that it was on main thread. How is that possible?

[@aparnarvd4343]

Thank you for sharing the valuable information

[@iCode_Happy_Coding]

Glad that you found it useful 🙂

[@raysubject]

And chance this is usable also for communication between realtime audio thread and main thread ? I mean if you are trying to communicated between realtime audio thread and main thread there are some forbidden things like using of MUTEX - so any chance all this Actors aren’t using MUTEX ?

[@ilyablinov4979]

Thanks for this lesson)))

[@sandeepsuthar4582]

When should we use weak and unowned in swift?

[@iCode_Happy_Coding]

Mostly, when you have guarantee that the object won't be nil, unowned can be used. Otherwise, prefer weak to be safe. There are other details too.. I'll try covering them in the video that I'll do weak, unowned etc. Thanks for the suggestion 🙂

[@sandeepsuthar4582]

@@iCode_Happy_Coding I think if i will follow your videos, will become master certainly. Please guide us how to prepare DSA for beginner to expert level and then solve interview’s online test with all test cases. I have seen some UA-cam lectures but i need something that covert step by step and all content should have at single place.
I am rejected 10 times from Nagarro and other reputed company’s online test.
Thank you

[@harshpanwar159]

Sorry dear i would like to correct you... why you are blocking the queue using sync operation, you must use barrier flag on concurrent queue with async operation always.

[@harishlakhwani5072]

Hi Pallav,
Thanks for the video.
I tried with same approach but surprisingly it worked if I used the 2 queue like in your video but whenever I tried with 3 queue it is not working. I am sharing the code snippet for the same. Share your thought on it.
actor Flight {
var availableSeats = ["1A", "2B", "3C"]
func bookSeat() -> String {
let bookedSeat = availableSeats.first ?? ""
availableSeats.removeFirst()
return bookedSeat
}
func getAvailableSeats() -> [String] {
availableSeats
}
}
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let flight = Flight()
let queue1 = DispatchQueue(label: "queue1")
let queue2 = DispatchQueue(label: "queue2")
let queue3 = DispatchQueue(label: "queue3")
queue1.async {
Task {
let availableSeats = await flight.getAvailableSeats()
print("Available seats \(availableSeats)")
}
}
queue2.async {
Task {
let bookedSeat = await flight.bookSeat()
print("Booked seat \(bookedSeat)")
}
}
queue3.async {
Task {
let availableSeats = await flight.getAvailableSeats()
print("Available seats after booking \(availableSeats)")
}
}
}
}

[@joshuawalker7530]

Why do you think this didn't work? It works for me. I get
Booked seat 1A
Available seats after booking ["2B", "3C"]
Available seats ["2B", "3C"]
In the console, which is what I would expect. Only one task is booking, the others are waiting, then printing the available seats.

[@arunj3344]

@@joshuawalker7530 Can you run 5 times and check you are getting the same results, Its not working for me as well with actor giving different results