Threads in iOS Swift Tutorial in Hindi | Concurrency and Threading concepts for beginners
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- เผยแพร่เมื่อ 30 ก.ย. 2024
- Threading is an important concept of swift programming, when you are learning swift threading in swift is considered as a complex topic.
Interviewers always tend to ask questions like what is threading in iOS, concurrency in iOS swift, or to explain a race condition, etc. Several more complex questions and if your concepts on threading are not clear you may not crack the interview round which is sad.
This iOS multithreading tutorial from codecat15 is a starting point for swift beginners and swift professionals to understand the basics of threading before they jump to complex tasks. Grand central dispatch and iOS race conditions are two of the most common questions or iOS project concerns when we talk about a long-running task in the background.
This swift tutorial talks about the basics of threading, where we can understand what the concept of concurrency and threading is before we get our hands dirty with code.
Give are the list of topics that are covered
1. Difference between main vs background thread
2. What are serial and concurrent queues
3. Pros and cons of serial and concurrent queue
4. Race condition
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#whatIsThreadInSwift #concurrencyInSwift #threadInSwiftHindiTutorial
very informative for cracking interview questions about threading. very helpful . thank you so much for sharing detail information
This topic is important not only for beginners but also for many experienced professionals, many times experienced developers miss out on one critical part of how threads work which later results in hours and days of debugging. My take on this is if your core concepts are clear you can knock down any complex multi-tasking task with ease and without hours and days of debugging. That being said please do watch the video till end and if it helps then please subscribe and share this video with your friends :)
Very awesome video as usual, Just one doubt Ravi, Here we added Thread.sleep is just because if there is network issue which can take time in real time scenario then just to show that scene we added that right?
Also one more doubt that what is the difference between thread and queue means I know their types but what is the difference? Means in a serial queue there are threads? What is overall picture of the queue and thread?
yes just to show the network delay i added that
Queue: They are container for our tasks, and contain information about how a particular task should be executed.
Thread: They read the queue and execute the task in them
@@CodeCat15 Thank you very much for clarifying my doubt Ravi...
you are very creative person
I try to be creative person but not a creative developer :) Hope this video was helpful, feel free to post your questions on the topic will be happy to answer them or any feedback/suggestions in general.
Brother I want to thank you so much for this so important series. You are simply AMAZING. A teacher like you indeed is what everyone needs. Thank you again. Please do not stop and keep up the good work. Developers like me need teachers like you.❤️
I think teacher or sir is a highly respected post and I consider myself a learner just like you and whatever I have learned I am simply sharing it out, maybe one day in some comment or email I will learn something from you too and that's how I look at it.
For the sake of conversation, This is a short and sweet introduction of Queues in Swift. Wonderful work. Really helpful. :) #CheersToCodeCat15
I am glad this was helpful Darshan, I like keeping things simple :) Do share this with your iOS group or with anyone who wants to learn the basics of threading in iOS the entire threading playlist will be of a great help to them
what async? is there a difference between concurrent and async? sorry I am new in development so I am trying to find out why did you use async here.
but you did not define the definition of GCD ... what is Grand Central dispatch ? when and why we use GCD
Apologies i missed this but i wanted to show this in a live project coz then it made more sense like download from multiple api and one complex scenario pretty much common in every project
Hi Ravi, I really like your videos.
The best part of your videos are, you take real-time examples and portray the functionality.
I have a couple questions,
1. In concurrent queues, how do we know that a specific task is completed first?
2. and how can we track that all the tasks are completed in concurrent queues?
3. what are the other things which we can use apart from NSLock?
it would be great if you can provide me some insights on this.
Hello Susheel, welcome to the channel, we cannot control when the concurrent queue complete a specific task, as you can see its by design, we don't really know which task is going to be completed first and a lot of it is being controlled by the system thread to which we don't have any control.
NSLock however I did not use much but its always a good idea to know about things like NSLock where you can make sure that two threads are not simultaneously updating a resource and you get a bad value (race condition).
If you want to know if all the task are completed I would not use a concurrent queue, but I would use a OperationQueue where I can control things more and op queues wait till all the operation in the queue is completed.
Hi Ravi, thanks for sharing the info about Race Condotion.
Instead of concurrentQueue.async {..} and NSLock(), can we use concurrentQueue.sync{..} to avoid race condition?
Not always you can just make a call serial and be done with it to avoid race conditions, am not saying it won’t work but then depending on your use case there are certain other patterns that you can try to avoid race conditions many developers may suggest to use semaphores and yes they do handle race conditions but then they open doors for other two issues which is deadlock and priority inversion so my suggestion is look at your use case and then make a choice of the pattern or tool that you are going to use
@@CodeCat15 Okay. Thanks a lot bro.
Thanks alot for very clear and crisp explanation and the examples you used is so good that any one can understand your concepts at the very first time.
Thanks again.
Am glad this was helpful Bhanushree, please feel free to ask questions and do share the video with your iOS group
bhai tumhara tutorial bohot achha hai ...but request hai vai thoda dhire bolo to fir ye aur vhi achha hoga savi ke liye
Jee bilkool is baat ka mai dhyaan rakhunga agle sessions mai, aur bhi koi suggestions hongaye to zaroor dena 🙏 and welcome to the channel
@@CodeCat15 vai tumse bohot kuch sikhna hai mujhe ... bas aise he tutorial chahiye mujhe ... tum bohot achhe video banate ho ... barte jao bhai
Thanks a lot man. Please keep bringing this kind of videos really cleared this concept. And please continue this series
Yeah sure, i will surely get back to this series soon. But thanks a lot for your comments really appreciate it. Feel free to ask questions if you have any on this topic.
Do subscribe to the channel and share it with your iOS group
Excellent sir, i have learned new things for every video. Now got it NSLock usage.
Glad to hear it!
wow this is really great explanation dude , please keep making more and more videos and there is only one suggestion to you always take bit easy example because im new to coding but after so long i learnt everything on depth this is really great . 🥰
Greetings and Welcome to the channel. I am glad this video was helpful.
Take one step at a time don't rush and always practice like look at the code I do and try coding in parallel with the video so that you get the concept and if you have doubts feel free to ask via comment or on discord or slack.
Thank you once again 😊
awesome explanation , it helps me a lot . thanks for making this kind of videos . keep it up bro
Glad to hear that, please feel free to ask questions and do share the channel with your iOS group
Hi Ravi.
Can you explain why all the UI updates should be dun in the main thread?
I have made a video on lazy loading and over there I have shown why heavy operations should not be done on main thread, do check out that video and if you still have doubts then please feel free to ask more questions I will be happy to answer them
Lazy loading and Image caching: th-cam.com/video/Bytv3PJjNi4/w-d-xo.html
i love the why u use examples dont have to play again to understand , u make it very simple
Thank you 🙏
Nice explanation bro.. Your every video have unique and rich content... Keep it up...
Thank you I am glad this was helpful
Good work Ravi, it really helped to understand this topic ,this is the best video I have seen so far in your channel
Glad this was helpful Waseem
Can you provide English subtitles ?
Yes I’ll work on it, thank you for the suggestion
wow amazing explainatin
maine Yogesh patel ke 3 new video dekhe phir bhi kuch samaj nahi aaya but ha aapke 2 video me sab samaj gaya me aeisa nahi kah raha hu ki uss channel ki quality low thi nahi par aap jo explain kar rahe ho vo amazing hai
Hey Hardip, happy new year. I am glad ye video helpful tha aapke liye, aur koi doubts hongaye to plz zaroor puchna aur aapne ios group mai bhi ye video share karna
thank you so much brother for make it simplified.
Glad this was helpful, please feel free to ask questions on this topic, and I do recommend going through the threading playlist for a deep dive details into the topic, Do share the same with your ios group.
Threading playlist: th-cam.com/play/PLb5R4QC2DtFuSE3wpJAqvFRbal5-7sAwr.html
If app's task is to download 2 gb data from server then how will it be performed? If downloads fails in-between due to any reason like internet problem, phone call or etc then how to continue that download from where it is interrupted I mean if 600 mb data is download then it will continue from 601 mb rather from beginning. How to achieve that? GCD or NSOperationsQueue?
I would go with an operation queue here because if some calls or anything comes then we can pause the download and resume it back, however I would avoid doing an in-memory save and would save the data in the app directory.
There are also other factors in play here like what if the user kills the app in that case whatever we have downloaded so far is gone. 2GB is a big file and what if the users phone does not have that kind of storage because they may have other apps or files and the disk space could be just 1GB left so maybe we want think about why we are downloading a 2GB file on the users disk at the first place.
Another use case is the user is on mobile data so you don't want to download such mega files on mobile data or perhaps you want to give a setting in your app which says download huge file on wifi.
If the app is put in background I would still write some code to perform background downloads so that my download is not interrupted.
So too many uses cases here to think about before we write the code but Operation queue is surely the one that I will suggest using in such use case.
@@CodeCat15 I appreciate your suggestions and use case. Thank you Ravi. By the way India me data to almost free hai.. hahaha..Even I also used to download HD movies from Telegram via mobile data only
Ha re but fir bhi public ka data jaldi khatam hua aapke app ka vajaha se to it does not look good coz then we get bad reviews on app store also data free hai almost but user ka disk space nahi 😅
@@CodeCat15 hats off
I liked the way you explains with those examples. Thanks brother :)
Glad it was helpful 👍
thank you so much brother, for such informative video about very hot topic in iOS development.
very helpful and smooth to understand . good job :)
I am glad this was helpful Sachin, welcome to the channel please feel free to ask questions and do share the same with your iOS group
@@CodeCat15 sure bhau ...
Very Helpful to me. Big Thanks Code Cat
Hello Kiran, welcome to the channel I am glad this video was helpful please feel free to ask question on this topic and do share this with your iOS group :)
Probably the best channel to learn iOS 👌👌👌
Thank you for your kind words
Superb!
Hey Ravi, First of all thanks for the awesome content, and most amazing thing about your lessons is you explains everything with a real life scenarios. Sometimes what happens we knows the concepts but no idea how and where to use it but as you gives an examples its really helpful. Thanks again.
Glad the video was helpful Sandip, do ask questions if any and do share the video with your iOS group
Hi Ravi, why do we have to update the UI in the main thread only? What problems could occur if the UI is being updated on background threads?
The UI runs on the main thread and hence the UI needs to be updated on the main thread always.
The UI will fail to update or worst you will get a run time crash if you try to update UI from background thread.
Let me know if that answers your questions and if not please feel free to ask more
@@CodeCat15 yes I got it. I was thinking why apple runs UI update on main thread, now I know after reading some articles, main thread is serial , it has highest priority by default, and we have only 1 main thread , all these contributes to above conclusion
what is mean by dead lock? pls give me a clip..
when two threads are waiting to gain access to a common resource and they wait forever is when a deadlock occurs,
here's to explain it more simply when I was a child me and my brother used to wait for my mom to finish her TV serials and give us the remote and we were just waiting to gain access to the remote control ( resource).
In iOS resources can be a file, database or plist etc, in a multi-threading environment two threads (me and my brother) are waiting to read or write to the resource (remote control) but can't because that resource is already occupied by some other thread (my mom).
Hope this explains what a deadlock is and if not then please feel free to ask questions I will be happy to answer.
Hey bro you completely clear everything.....keep it up
Hey thanks Deepak am glad this was helpful, plz do share this channel with your iOS group on WhatsApp or Facebook too 😊 and once again all the best for the interview
amazing this tutorial. 👍🏻
Thanks Ahsan, I am glad you liked it. Please feel free to ask questions on this topic I will be happy to answer them and if you think this video can help other iOS devs then do share this with your iOS group on Facebook or WhatsApp :)
@@CodeCat15 Sure Sir
nice one
please be more frequent with videos. Your videos are great😁...
Really you have the simplest and the best explanations!
I am thankful for your comment means a lot, there's an entire playlist on threading I request you to watch that as well as it covers all the scenarios that we face while building an app
Threading playlist: th-cam.com/play/PLb5R4QC2DtFuSE3wpJAqvFRbal5-7sAwr.html
Sir just want to ask you one question - When i go to interviews, I really struggle with questions about technical skills like dsa etc.
I can answer questions related to swift and implementation of things in swift. Is their any specific tip would you like to give me?
Awesome 👏
very well explained.. Thank you
Welcome to the channel Debika and am glad this video was helpful. Please feel free to ask questions on the topic
Wow. Awesome example .what is NSLock thing ? 🥺. I heard that even first time. Is it in iphone developmemt or mac developememt ??
I used this once when i was facing a deadlock scenario in my project a pretty handy tool you should know, there’s a lot new things which are lined up for the upcoming videos and i plan to continue with the thread series soon once am done with the mvvm series
Thanks a lot for your comment buddy and feel free to ask questions on threading if you have some will be happy answer them
@@CodeCat15 Yeh. Good going. Waiting for other videos. Love to watch your videos. and always curious for your upcoming videos. Actually i was thinking to start ios channel but after watching your channel i feel good that i didn,t started that. Your speech and the way of explanation is totally different. and All can understand easilly. Thanx a lot once more to improving our knowledge.
@@Techopia Thank you for such kind words, it really motivates me to make more of these videos. All I ask in return is if you can share this channel with your iOS group would appreciate it
straightforward and good explanation. easy to understand
Thank you for your kind words buddy :)
Very helpful thanx for your effort
Glad it helped
Hi Ravi the way you teach is really amazing. thankyou so much to put so much efforts on your video
My understanding: Serial Queue results when threads (each thread executes a task) run synchronously, that is one task after another.
Concurrent Queue results when threads executes task asynchronously and are in parallel that is each thread run on different core of a processor.
Doing great content. Thanks for this amazing tutorial.
hi codecat does sqlite 3 database support multithreading operation in it.
Short answer yes, but be very careful coz sometimes you may get an error which says db is locked or something like that so i advice to use lock as you have seen in this video to make sure such hiccups don’t happen
Am curious, does your app has multi threads trying to modify records in the same database?
@@CodeCat15 yes many time I have got the error as dB is locked whenever I used to get the data from the server and save it to the local database my one requirement was to download the pdf file from the server but simultaneously our main thread where user will be able to do the other kind of click bt I refused it because of the dB locked error.Do you have any such example where I can perform background task of file downloading and do the user click operation for saving or retrieving the data from the database and one more thing I have created the Singleton class for database
if your db or api calls are on the main thread it's going to cause tons of issues for the user where user will feel that the UI is broken or froze or the app has crashed but did not die completely and you don't want to give this experience to the user.
The remedy for this is to use URLSessionDownloadTask here and once the download is complete then you need to save the PDF in the db so there's a sequence here you need to use serial queue once the download is done just pass the data to the main thread as I have shown in the API series using the DispatchQueue.main.async closure which should do the trick.
I don't really have any samples for this but this should probably get you started. If you need more help then put your code on github and we both can review and improve it
Simply amazing this tutorial
Thank you Hareesh, let me know if you have any questions on this topic, will be happy to answer them. And do share this video with your ios group on WhatsApp or Facebook
Really loved the explanation !!!
Glad it was helpful Shatadru, welcome to the channel
@@CodeCat15 I already subscribed & really learned a lot of things........ Thanks again
Great example! Thank you
sir baki videos kab a rhi h ..??
baaki k videos core data series k baad release karunga ispe, specially on dispatch queues
Very much appreciated!
Hi Ravi,
can you explain how can we reduce multi-threading in our project?
Can you please elaborate on that? What do you mean by reducing multi-threading?
@@CodeCat15 Is multi-threading bad for our project?
The entire iOS device runs on multi threading to perform its task, it actually makes the job easy and is used to perform heavy operations in less amount of time so multi-threading is a good thing in fact many of the classes that we use from foundation implements threading to get the job done