SwiftUI Tutorial: What's the difference between @State, @ObjectBinding, and @EnvironmentObject?

[@twostraws]

Watch next: How to fix slow List updates in SwiftUI - kzbin.info/www/bejne/nmG2mJScjNyinpo Questions? Comments? Tweet me @twostraws.

[@simonbachmann2120]

IMPORTANT: ObjectBinding/BindableObject are deprecated now! @ObjectBinding is become @ObservedObject and BindableObject protocol is become ObservableObject as well as willChange become objectWillChange.

[@niklasnickel]

Simon Bachmann Thank you so much! This indeed saved a lot of trouble...

[@sreekumarmenon]

Was going to ask the same, I started swiftui recently and was confused with seeing ObjectBinding in this video! thanks

[@MattiaRighetti]

I was going to ask when to use ObservableObject and BindableObject, thanks! 😊

[@flexmcpee]

Ah that makes sense. Only started learning SwiftUI of late and was confused seeing those. Thanks for clearing up.

[@ShalevLazarof]

thank you 👌

[@abcd123906]

If you are learning SwiftUI, you literally NEEEEED to watch this video! This scratched so many cognitive "itches" I had about Swift, it's almost scary. Thank you, thank you, thank you!

[@frimpongopokuagyemang8052]

Saying that this video is "HELPFUL" would be an understatement. However, I have no bigger words. LOL! In short, THANK YOU DUDE! The way you make things clear, is just something else.👌👌👌👌👌

[@kevin-u7719]

I have saved 1 hour while watching you 20 minutes concrete and robust explanatory video. Thank you Paul.

[@coolisfoolable]

This is THE best tutorial I've seen so far! And boy I've seen many. Thanks Paul!

[@chrisual]

Much of this video is not appropriate anymore, but the description of what state, binding, etc are is TOTALLY worth watching. I have watched so many videos, but this is the first time I have understood these concepts. Well done Paul!!

[@chezchezchezchez]

I’m just getting started. What would you recommend is the perfect video right now for this information? Thank you very much.

[@marlhex6280]

Please make more! I love the way you talk with passion and interest! Also the way you edit the videos with a final touch! Awesome job!!!

[@BroadcastYOzZelf]

I'm used .Net's, old Xaml's and to Qt Qml's (super elegant) property bindings. I was exactly looking for an intro on how SwiftUI does this. You found the perfect level between giving an overview and going into detail. Thanks!

[@JVancity]

Been messing around with all three for a few days now, getting things to 'work'! This video really hit the nail on the head and now I truly understand the why. Thanks Paul, you're a legend :)

[@MatthewCawley]

I've watched a few different videos on @State, @ObjectBinding and @EnvironmentObject and it didn't make that much sense. Your explanation was amazing, clear and high descriptive. Great job :)

[@AndreaCiani]

This is the best video about this things I have ever watched. You make simple and more complicated examples and you describe them extremely well. Congrats and thanks!

[@uberunix]

This is an absolutely fantastic explanation for someone like me who doesn't know enough yet to distinguish the significant bits of what the docs are saying. Thank you so much! :D

[@brandonr.8784]

Been stuck on these concepts for days, this video really help improve my understanding!

[@nexplusedinburgh5545]

Wow! Best SwiftUI video in the whole KZbin! Thank you!

[@dhavalnena7386]

Every time I watch your videos it gives me a deeper understanding of the topic explained. Thank you so much!

[@rickstrickland2464]

Your clarity is awesome. Can you do one that uses Core Data?

[@alihodroj9559]

maybe he already did one go check : )

[@rickstrickland2464]

Core Data with SwiftUI

[@alihodroj9559]

@@rickstrickland2464 oh now i get it : )

[@brunofulber4688]

I wasn't able to make it work too, got to figure a good way to make managed objects conform to bindableObject

[@stephencollins2831]

I’ve been an iOS dev for 1 week :) i think you can pull initial startup data out of core data in the scene delegate. Then pass that data into EnvironmentObjects so it can be accessible to all child view from main. Then each sub view can perform CRUD operations on it with core data. This method may not be great if you’re pulling a lot of data into memory. Perhaps there is a better way? Would love to hear!

[@triXtyle]

Amazing video, teaches us core concept in a very good way. BUT The Victor Hugo reference nailed it!!!

[@JellyLancelot]

These videos are soooooo good. Your teaching style is amazing and easy to follow, but not slow enough that I'm skipping around for the info. Clear, concise and concentrated. Superb! Also, you explain the WHY. It's so important, but what so many people miss.

[@ac12484]

Best no bs intro (experienced programmer here)

[@thomasanderson1416]

Can we refactor all the states out of view structs in a single file for example, and still access and control them from all views? That would be so awesome.

[@koz]

Absolutely great stuff. You're making my Swift-learning experience a lot clearer. I'm intrigued about "who taught you?" though. Because I get the feeling you had a good teacher. (This is where you say you're self-taught too)

[@farukenstein]

"please just stop and thnik for one moment how amazing that is" is the one possible definition when it comes to swiftui.

[@rixantos]

Great video @twostraws very well explained and delivered! Time to write some SwiftUI...

[@JacksMacintosh]

Oh my goodness. This @EnvironmentObject thing might just save my life. Thank you thank you!

[@Mriceman2002]

You explain very easily even without the help of your two dogs :) You are the best ! Hope you continue to make many more videos!

[@dlbYT8]

Your content is gold. Thanks Paul!

[@mistermagic4507]

Finally my company decided to start the next project using SwiftUI on iOS 13 and here I am, BOOOM :)

[@oliverbarreto1838]

Great great tutorial... first division university class... core concepts really well explained and introduced vía telling an incremental story... a must watch... Apple should absolutely use this video and upload it to SwiftUI developer library 💪🏻😀😎

[@ZoeSummers1701A]

I think this is the best tutorial video you’ve ever made.

[@robertsan2654]

Being an iOS & React developer feels great with SwiftUI. :)

[@Nicolas-is3gq]

Excellent tutorial, I finally understand these concepts after trying a few other sources. Thanks Paul!

[@yixe2253]

You're a great teacher, easy to understand.

[@petersuvara]

Paul, we generally keep state as a completely different place to the UI components themselves, this provides a layer between state/transport and UI.

[@numerics77]

Xcode 11 beta 7, get errors at the 10:25 mark.. Cannot invoke initializer for type 'TextField' with an argument list of type '(Binding)'

[@24Doggi]

Nest video for a guy who comes from java and python. Thanks!

[@1sndct]

Great explanation, been trying to grasp this concept for a loooooong time, its finally coming together. Thank you

[@Dan-t6h2s]

Just learning Swift.. this was really helpful. And I caught your bread and 24601 reference… Cheers for that one!!! 🥃

[@torcelly]

Hi Paul. Thank you for this awesome video. Excellent tutorial. Your explanation is accurate, concise, and clear. Congrats!

[@idembele]

5:46 beautiful example on how @State keyword works

[@wizzards44]

Paul you are smashing it again!!! Great breakdown of new tools!!!

[@shivammahendru6122]

Much needed explanation!! Thanks Paul

[@chettodust]

What do we do at 18:40 now that Scene Delegates are not produced in new default SwiftUi files?

[@PeterPurmonen]

Excellent! All gaps flled. Thank you. 👍🏻

[@thomasanderson1416]

Question please? After using ObjectBinding on the User class. How do we access it from different views with recreating a new instance?

[@kronosDE]

The Textfield mentioned in the video doesn't work anymore. The new API is now something like that: TextField("placeholder text", text: $myInput)

13:40 Will it make an infinite loop as the first textfield changes reflects on third textfield and vice versa ??

[@thealchemist1480]

This is well described and very helpful video indeed. Keep the good work up,,, you are doing a commendable job for the community.

[@michaelnajera7958]

If multiple windows are created, say with a split screen on iPad showing two windows of your same app, will SceneDelgate pass the same reference of userData: User to both ContentView's? 18:45

[@michaelrogers6935]

Apple should've just let Paul see SwiftUI a week early and link all of their documentation to hackingwithswift.com. That would've saved a lot of developers a lot of time. What an awesome explanation!

[@olepetersen4460]

You make really great videos, and thank you for that. Regarding this one: My projects have no SceneDelegate, so an update would be highly appreciated. Where and how do you set up the global varible in the .app file?

[@marcoespinoza3327]

Stumbled upon your tutorials and explanations and it’s amazing. I am currently doing QA work and do some dev work too as I’m learning. However, this is preparing me for the future and I really appreciate your videos and explanations. I still want to transition from QA to dev because it’s more interesting but I know I have a while to go.

[@thomasipad7719]

Would a "@StateObject" be enought for the Class, without using Combine?

[@littletalk8860]

Great explanation, love your professional tutorial

[@alisonsmith5749]

Hi Paul, at ~15:15, you mention making sure to call passthroughsubject on the main thread. I searched all over and can't figure out how exactly to do that. Could you clarify via a code snippet on how to write that function on the main thread? Thanks!

[@francescofuscaldo2364]

Great videos, thank you so much. I'd like to suggest you a subject for the next videos, it would be great to see how to work with CoreData and SwiftUI!

[@piyushgeorge1847]

Best tutorial for the states. Loved it

[@crewshin]

FYI: It looks like the BindableObject code is already broken with beta 4 :( I'm getting an error that "User" doesn't conform to protocol "BindableObject".

[@A-Plays]

use ObservableObject instead and when u are creating a variable out of it use ObserevedObject for it.

[@di_nerd_apps]

BEST EXPLANATIONS !! BIG UP!!!

[@michaelrogers6935]

Just one question: I can define var isAuthenticated = false, and then create a mutating method, toggleIsAuthenticated() to toggle it -- the compiler is happy with that. But, if I try and pass that into a Button, Button(action:{self.toggleIsAuthenticated()}, label:{Text("Toggle Me!")}), it is not happy -- and gives me the Cannot use mutating member on immutable value: 'self' is immutable error. Why is that?

[@vipullal7689]

Loved it! Clear tutorial.

[@arkemal]

I've learned a lot from this. Thank you!

[@AnkitRathi7]

Everything clearly explained. Just one doubt, how can I use 2 user objects(like user1 and user2) from Environment?

[@andrei-un3yr]

this is now quite confusing to me. I thought that what you use here as @ObjectBinding is what I thought to be @ObservedObject. What's the difference between them?

[@tajapan]

All the didChange code can be replaced with @Published var username = "@twostraws"

[@anata.one.1967]

Here's a really interesting problem, how do you do object binding of type int/double with textfield??

[@someonlinevideos]

Ananta Shahane wouldn’t you just use state?

[@haraprasadsenapati6662]

Awesome video Paul

[@pitkaldewey1078]

I was using a Class with OservedObject in a different View. But the text won´t update there. Anyone can help me and tell me how to update view programaticlly?

[@alexanderfitterling]

Thank you so much for this video. You have amazing good teaching skills!

[@guitaripod]

Now this now a year later, it's so clear. Thanks

[@thomasanderson1416]

Why can’t you change properties in structs? They’re marked ‘var’ and not ‘let’. In all other languages you can change them all right.

[@sreekanthiragam2305]

I have a query on @state can not be used for reference types(viewmodel classes). I have seen some code examples where @ state is used for the model object in the view. I also read that @objectbinding might not update the view even if the model changes.

[@andrevdw747]

What a clear explanation! Thanks! Also understandable for a beginner like me :-)

[@MeteoraEra]

Your videos are awesome man.

[@dimiutube]

Thanks for the great explanation, Paul! Now most of the magic behind SwiftUI is much clearer for me :-)

[@niklasnickel]

Thank you very much! This was the first time I really understood what was going on...

[@mattd5419]

So what's @Binding used for?

[@kimtipatel7]

U r superb explaining ❤

[@bnkohrn]

If an environment is basically a key-value store that uses the object's type as the key and the object as the value, then can you have only one object of a type in an environment?

[@twostraws]

Not quite. It's actually key-value pairs, see: www.hackingwithswift.com/example-code/language/what-are-keyvaluepairs - that allows duplicates.

[@limtc]

This is the best explanation so far! However, I do hope you can add in explanation of @Binding besides these 3.

[@nicolinden]

Hi Paul, I like the @EnvironmentObject, but now you set userData as the environmentObject of the ContentView, can you also set more then one object on a view as a environment object though (like an array of objects)?

[@max500k]

Awesome video, super concise!

[@fortune1109]

Hi Paul, thank you for the tutorials you are making. Helps me alot.

[@puhgeh]

What's the difference of @Published and @State?

[@JacksMacintosh]

Wait. If the environment works like a dictionary, and uses the object's type as the key, does that mean you can't have say, 2 User environment objects?

[@ankitthakur85]

These clarity is awesome. Could you please re-visit this again, once GM release happened for iOS 13. As the Combine framework is also in beta, and could have changes before GM release happens in September/October month.

[@SehajChawla]

Love all your tutorials. Would be great to have in depth tutorials on Combine framework as well.

[@raysubject]

So you cannot pass multiple instances of same class into enviroment, because it uses class name as key, am i right ?

[@dhavalnena7386]

Question: can @EnvironementObject be replaced with Singleton class? as we can use it anywhere in the app wherever required similarly to what @EnvironmentObject does?

[@tomtubbs6254]

Thanks Paul - great visuals for the video along with your clear instruction. +1 for the request for a basic Swifty I app that uses core data.

[@danielcrompton7818]

So what is @Environment vs @EnvironmentObject

[@josephharrell6793]

Can the json file be replaced with Core Data?

[@sergehulne]

Excellent tutorial! Thanks!

[@IsrafilGuseinov]

Use of undeclared type 'BindableObject' , what is that? Some bugs in swift? I can't do nothing,

[@Seitenwerk]

because its deprecated. many things changed in the last month until the official release happened. you will have to teach for more recent tutorials for how its done in the release version oft combine

[@IsrafilGuseinov]

Alexander Winkler thank u man

[@A-Plays]

@@IsrafilGuseinov use ObservableObject instead of BindableObject and also when u are creating an object out of it use ObservedObject.

[@IsrafilGuseinov]

ali pishvaee I already understood,thank you

[@al-badyah5351]

Can you explain to me when a notification was clicked, it must be redirected to desired page in IOS

[@xcollector1590]

Hi paul, does the way environmental object work similar to userdefault?

[@gameover-je9ng]

Hi paul ... how can i create my own url JSON file , eg. etc ... ? need to have apple developer account ? i mean not free developer account . Help me plz i want to know , i searched on online but nothing found 😞

[@doanvietios]

I love SwiftUI n I love this Tutorial too. This is awesome.

[@TK-tg1hx]

You are really brilliant smart.... What a wonderful explain!? Thank you sooooo much!

[@Goremachine]

What I don’t get is why a new user object needs to be instantiated in every view that needs to know about the state of the user - there is only one user in this case. Shouldn’t user be a single instance referenced by all the views?

[@chezchezchezchez]

Hello! Did you happen to find out? I’d like to know also, thank you!