Learn to Program with C# - DELEGATE & EVENTS - Advanced Unity Tutorial

In this video we take a look at using delegates and events for creating a callback system in unity! Also known as the observer pattern! For more information and in-depth knowledge of C# and Unity, check out The Unity C# Survival Guide, available at GameDevHQ.com
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[@nobytes2]

I've watched hundreds of videos on delegates and events, and you freaking broke things down and explained like a rock star! Thumbs up!

[@Marc28shooter]

Seriously mate ! I just got an internship in a small studio and they asked me to learn about this because I didnt even know Delagate. Now in 19min53secs I've learned it , understand it and know how to use it. Thanks !

[@GameDevHQ]

Awesome! Glad to hear this helped you!

[@ahbarahad3203]

how can you get an internship without even knowing basics of programming?

[@opticalreticle]

@@ahbarahad3203 small studio

[@aliaboshady12345]

@@ahbarahad3203 Ok please don't be that show off guy. It's not bAsIcS oF pRoGrAmMiNg. It's a fairly advanced topic.

[@adgamesadnan]

Same here, my First day in a software house as an internet, and I am asked to learn these topics, that's why I am here....

[@zacharyrenfro3716]

Freaking phenominal video! I recently watched a tutorial series for a personal project that utilized delegates and a lot of the reasonings for what it was doing went over my head. This video explained things expertly and everything just clicked after listening to your explanation. This is the easiest subscription I think I've ever given out and I will definitely be diving into more of your tutorial series. Thank you for spreading the knowledge in such a clean and efficient way

[@johnmanjohnston]

This is actually one of the best tutorials on the topic that I've seen! A lot of the other ones are a little too complex for a dumb-dumb like me, but this is easy, straight to the point and the pacing is awesome. Don't stop what you're doing man, awesome tutorial!

[@indigodoyle]

OMG years later and this video is still so useful. Thank you! Really helped me after watching 10+ videos about this!

[@Guicepp]

You have an incredible feeling for explaining the mindset behind coding. Most of the time you need to dive in and experiment with it to really understand what it does. You are by far the best! Awesome to have you back!

[@harrysanders818]

Thanks for the entire series. Was some month away from Unity, these where the perfect starting point to refresh it and on top learn the next steps such as the use of events. This video helped me further and finally clearly understand its usage and use cases ! Thanks a lot!

[@GameDevHQ]

Absolutely! If you're finding yourself in need of more assistance, or just a place to bounce ideas off of - come hang with us at gamedevhq.com/ :)

[@lhorbrum1818]

You're awesome! Your tutorials are what got me started. I really wish you were more active, as you're one of the best out there! Thank you so much for all the help you've given us.

[@GameDevHQ]

Have you taken my udemy class? You can join my Discord channel. I'm there daily. If you need a discount just visit here: gamedevjon.com/discounts

[@saadbutt2186]

Thanks. I' am struggling to understand this topic for a long time. I' have finally watch your video and it clears the purpose and concept of delegates. :D

[@pra53t10]

actually I follow your tutorial from fundamental until advance, and i think your channel is a good place for developers to understand code in unity, keep the good work jonathan

[@heavycoder6559]

The best way to teach codding is through implementation with examples. and showing the Flow. You are amazing at it. I am loving your tutorials about interfaces and delegates.

[@kryptoidkryptonic8696]

I watched this 6 months ago and it was awesome but I didnt completely understand. Used it a lil but than didnt need it for a long time. I came back to watch again today and omg it all makes so much more sense. Thanks!

[@Korudo]

I started using delegates and events for UI and camera animations. I had no idea I was using the Observer pattern. Thanks!

[@gokayakcay7093]

Thanks dude! Every tutorial is explaining how can we write events instead of explaining why it is used but in this tutorial you explained both of them.

[@SajithGame]

I was looking for week for this. Well explained. Thank you

[@zainulabdeen1469]

exactly what i was looking for the whole time and came up to the right dude . Awesome explanation keep up the good work

[@GameDevHQ]

Awesome!!! If you enjoyed this, come check us out at GameDevHQ.com :)

[@goomiac]

I finally undestood how delegates and events work after having watched several videos. Thanks!

[@josiahsaunders7358]

oh my goodness thank you. You explained this very clearly.

[@Unearthly89]

I always used Lists and Arrays and a ton of code to manage something like that...This is so much more convenient. :D Thanks for the Tutorial

[@GameDevHQ]

No problem! Make sure to check out the unity c# survival guide!

[@darkman237]

Glad to have you back!!!

[@jasbrela]

Thank you so much for all these series!

[@Melloboros]

I watched this video for the second time and the Observer Pattern finally clicked for me. I immediately jumped into to replacing some horrendous code and it works so nicely now.

[@djblast101]

wow......you open my world up for new code logic. thank you!

[@revolver878]

This video is a godsend. I was trying to get events to work for hours before I watched this video. The problem was that I was using findobjectsoftype to put a reference in the subscriber script, but the publisher kept on thinking there was no subscribers. I changed it to static and calling it directly and everything worked. I'm guessing because of the slowness of findobjectsoftype it created a delay thus returning null subscribers in the publisher null check(it would work if I looped it in update). Anyway thanks heaps John!

[@mahmoudmostafa9610]

Awesome, Waiting for the rest of the tutorial

Great video! Clean explanation with a nice example!

[@rgstudio7272]

Awesome great explained. I looking forward to see more...

[@Historyan]

keep it up! you great man. dont stop this channel.

[@pacocu9839]

Thanks bro! Very useful tutorial series, I learned a lot.

[@cuttlas2955]

dude you are back :) very good , your voice is older now :D and finally you are using visual studio Tnx god :D happy to see u again Jonathan, Pls give us more fantastic tutorials

[@GameDevHQ]

Yeah, I disappeared again. Hit me up for a discount code: gamedevjon.com/discounts and join my Discord channel. It's only for students. Then you can get me pretty regularly.

[@paccom193]

Omggg you are back :333 Miss your Amazing tutorials cc: I still yet to found better Teacher then you :3

[@Oxmond]

Great stuff! Really cool tutorial! 👍🤓

[@mehmetcomlekci670]

Your expression was good, I don't know English, but I still got it with automatic translation. Thank you for the video.

[@btiwari-games5279]

Thanks for very clear and detailed video

[@tariqashraf5855]

wow you are back after a year! welcome back

[@supertenchoo4271]

Great video this is the best youtube channel about game dev tutorials on youtube

[@Hincom]

Thanks so much!!! I was just want to know this!

[@TheDukeOfReason]

I had an idea about delegates, now I have a much better idea and can utilise them efficiently. Ace video

[@kinnith7stream614]

THANK YOU!. Excellent tut. Subscribed. 8)

[@GameDevHQ]

Thank you!

Nice~ you're back :D

[@longers2550]

I know how use delegates but I like you and your explanation method :) Cheers!

[@GameDevHQ]

Thanks mate! Glad you enjoyed it!

[@TedThomasTT]

Glad you're back :)

[@mamokoruhollen]

Thanks man You have amazing skills.

[@user-qy6im1lm6n]

thanks,I finally understood delegate and event.

[@NestedMango]

Thanks for sharing . It will really help me a lot

[@qenious]

you're a genius dude! thank you very muchhh

[@egangster01999]

Really well done. Thanks

[@alan138]

Wow, very clean, but i'm a bit confused becouse didn't know about singletons, i heard the therm before but neve dig into it, perhaps the times has come for that. Thanks for the advanced scripting series, it really help to dig dipper into coding in unity to produce good quality stuff.

[@jake-vr]

Great tutorial, thanks!

[@fateshow5303]

Great video!

[@zerenchen6064]

omg, i need it ty.

[@bigjamar]

Excelente..muchas gracias..!!

[@TrollographyStudios]

This video is seriously amazing

[@GameDevHQ]

Thanks! Make sure to check out the Unity C# Survival Guide for more and better videos on advanced c# programming with Unity!

[@TodiloDaSloth]

To add to this. Event are delegates basically. One main difference is that you can write yourdelegate = myfunctiontobecalled . which in many instances are incorrect as that might overwrite. Events only have += and -=. Also event does not have to be static. Static event handlers can be a bit dangerous as there can much more easily be memory leaks that way. However, in many cases especially in regards to Unity a static event is prefered (that way you don't really have to find all the objects that will fire the events).

[@chilpox3671]

I am begging you, do more of these

[@lauristamo1889]

Great tutorial :)

[@zeurinproducciones6795]

Another alternative 14:02 could be simply making static the event without the risk to access the player class from anywhere. GG WP

[@gregoryfenn1462]

Yes, he does this at 14:25 anyway (thus rendering pointless the whole need for a singleton player at all...).

[@simoneroselli7571]

True. But most of the times you don´t want your events to be accessible from everywhere, which is the case of a static event. Here comes in help a GameManager, which can hold most of the callbacks and expose only what really must be accessible, protecting the internal callbacks from being listened. It would be a topic for a next video.

[@shonik-cm6kn]

10:12 you can lock Inspector, select all enemies and put them all into array together.

[@reed9269]

there is that little lock button in the top right corner of inspector that helps so you can lock onto Gameobject with an array and then select mutliple things from hiearchy. : -)

[@michaeldoty]

Good stuff Jonny

[@shanestevens516]

Dude you are incredible

[@Alexander-pr2tu]

Thanks, nice vid.

[@khalilHazazi-5]

Thank you so much

[@brothergames8006]

good introduction. I am just in the process of designing my own callback system for my first game with the help of unityevent. Having the code more decoupled is almost always a good thing. However, while I jumped into the game programming I did not like it when I decoupled player movement and player animations. So I refactored this and made player movement and its animations more tightly coupled again, which led to fewer issues... Should I keep animations and its corresponding moves more tightly coupled or is there a better approach to this?

[@SkaiCloud562]

You made this so easy thanks for lesson!

[@gregoryfenn1462]

So anoymous functions, lambda and func and action... ? I would love to see a video on that! It's been over two years waiting!!!

[@stormcaster6322]

hi GameDev! Do you plan on making any more of these tutorials? They were super helpful to me! thanks

[@GameDevHQ]

Hey mate, we are! And re completely re-did this subject and added a whole bunch of content. You can find it inside of our Unity C# Survival Guide on gamedevhq.com

[@patrykszylin2049]

Great series of Advanced stuff :) . Are you planning on uploading more videos anytime soon @Jonathan Weinberger ?

[@patrykszylin2049]

I'm happy to hear it! I hope you're doing okay and I shall wait for new vids :)

[@ayoze013]

Thanks for those great videos, I have a question: testing it I saw I can store severals methods in a single Event and call all of them when I fire the event. How can I see how many methods are subscribed to my Event?

[@muhiramadhan591]

thank you, many many thanks, i finally got an idea about delegate and events, before seeing this video i learn delegates and event but does not really get what it is used for

[@lukegf0]

Thanks for the great tutorial! I am trying to do something like this, but i want the Player class to inherit from an abstract class or an interface so in the Enemy class i don't have to have a dependency on an implementation, but rather an abstraction. In other words, i want the Enemy class to follow the Dependency Inversion Principle. How can i modify your code to accomplish that?

[@funkyjedi]

Looking forward to next video! Will you be making this code available, as singleton code is hidden? Thank you.

[@funkyjedi]

ouch ;)

[@TheKr0ckeR]

Thanks! That's really great guide for delegates, how do i create that singleton inside region? I coulnd't reach the project file to check.

[@sivakrishnakarri5181]

yes...nice video...Can we hold a reference in update method..???

[@Martin-xf8be]

Thanks for a great tutorial on how to use it. However, I don't really see how it was more efficient - it just seems like so much more work. The array for-loop was simple and works like a charm, why change it?

[@IOSoraOI]

Thank you!!!

[@GameDevHQ]

You are absolutely welcome!

[@aaron4820]

LMAO, a Udemy course I'm subscribed to is going through delegates and events right now, they were confusing me quite a bit so I decided to look up more information, which brought me to this video. Half way through the video it was interupted by an ad, an ad that was for Udemy courses, and the ad was made by the very same instructors that I struggled to follow in the course in the first place.

[@GameDevHQ]

Ha, you should check out the Unity C# Survival Guide! ;)

[@aaron4820]

@@GameDevHQ Just bought it :) Will do!

[@lee1davis1]

I was really looking forward to understanding delegates and events better, but your first method to change the color of the enemies was a lot less code then your second. So I don't see the point to using either D's or E's except when needing to know when a function has been called. Can you explain this for me? Thanks.

[@F3ND1MUS]

ty

[@dougwarner59]

Pretty good video. 3:33 when you say the method signature matches the delegate signature I'm guessing you are excluding the name/identifier because that is part of the actual signature and they don't need to match. Note: The reason you use an event over a delegate is to allow the subscribers to access the delegate by only using the add (+ +=) and remove(- -=) accessors; which will only allow them to subscribe and unsubscribe to the event. this will prevent subscribers from making disastrous changes to the delegate such as setting it to null, changing it, or invoking it (which would be a bad thing.). You may have been trying to explain that, but it wasn't that clear to me.

[@wilezgiacio]

Hi, I'm Italian and maybe I didn't understand the comments (in the speech). It is not clear to me why to use the delegates when they can do without it. What changes? In what situation can it be useful? Why not use the 11:20 minute code? For performance?

[@ikergalardi5701]

welcome!

[@Damian_h]

danm bro your clean. i have a problem and my teachers dont really want to tell me how to use events because they say is too advanced. So here i am looking for solutions on my own. I have a game where u can buy skins and buffs in the shop but im trying to link the buff let say u pay 300 coins for a new buff with more jump str to reach new areas ¿it is possible doing it like this? with events because im using playerpref to keep my data saved.

[@GameDevHQ]

Checkout the Unity C# Survival Guide if you're serious about C# with Unity.

[@battlepants5198]

Where have you been i thought that you quit youtube which would suck because your videos really helped me with my programming

[@battlepants5198]

And welcome back :)

[@battlepants5198]

Sounds cool

[@ukwildcamping]

Jonathan Weinberger welcome back also 👌😊

[@GameDevHQ]

Aw, I'm getting ready to be back on KZbin more regularly. Click here: gamedevjon.com/discounts and get a code for my class. Then you can join my Discord server, that's where I've been. I apologize for not making a better announcement

[@discoveringmypath]

Just curious how this is more efficient? It seems like it is easier on the programmer, but we have a static event and in the background I'm sure it is doing a loop to call each Enemies Damage function. So I don't understand. how this is more efficient performance wise? Either way, thanks for the tutorial. Delegates and events seem a lot simpler than I expected.

[@simoneroselli7571]

it´s more efficient because you don´t have to deal with references and lists on your own. An enemy can spawn, subscribe to listen and unsubscribe on death, and you can forget about it.

[@amac333]

So deleting an object from the Hierarchy with the Delete key is running a Destroy(); function?

[@Danyu91]

So, how do you input the argument of the parameter, if it requires it?

[@arunachalpradesh399]

can you reply, i have watch tutorial where delegate subscribtion is done at onEnable() method but why you have done at start() method , what is the difference and which is the correct way. ?? please reply

[@Ragnark1]

Hmm... So is this similar to how event-driven programming works? I know that to add an event you have to use +=. Is a delegate what is used when you have an OnClick method or an OnFocus method in an application?

[@GameDevHQ]

Correct. Checkout the c# survival guide for more detailed information, practical examples, and challenges to help you master these awesome concepts.

[@pragmaticsystematic9727]

11:30 Is it seriously better for performance? I'm of the mind that events are always slower than directly accessing the variables.

[@mvviguilla]

Directly accessing is faster, but efficiency comes when you have to cache things at run time or throughout the editor

[@newsystem3667]

Are delegates supposed to be used in complicated projects only ?

[@GameDevHQ]

Not at all. I use them in very simple applications all the time!

[@profhammond1255]

nice cuts the video disrupting the flow, thanks rabbi.

[@gamefactory.official]

Can we use Interface instead of this?

[@FuzzyDPozzy]

1:54 CallbackmyExGirlfriendSystem , so with that way you can call her anytime haha

[@GameDevHQ]

haha!

[@equation1321]

lmao

[@WelshGuitarDude]

How do you do it without a singleton then?

[@darkman237]

Can this be expanded so you click on something with your phone/tablet and your buddies get the same click registered on theirs?

[@darkman237]

How would you do that mobile device to mobile device?

[@darkman237]

Thanks!

[@GameDevHQ]

Please ask your question with a few more details here: gamedevjon.com/vote/

[@marekrimal2371]

What if I dont want it to be static?

[@mrgyarmativlogoldaja]

If I wanna make a Multiplayer game, use the singleton it's no way. Isn't it? So I mean I can use in single player mode only.

[@GameDevHQ]

You could totally use this in multi-player. Client side development is all local.

[@lukenukem8028]

Delegate works without System., which you show later.

[@aleksandarstanisic1848]

wow