I'm glad you're able to follow along an understand. One of my biggest pet peeves is online courses that are hard to follow because the instructor does something and doesn't explain it haha. Let me know if you ever have questions!

Thanks for watching Daniel!

Old retired C programmers like me need teachers like him also!

He's the only one who literally and I mean literally gave us everything for free. Everyone else is money hungry who begins a topic and redirects people to a garbage course on another website that happens to be 75% off for a few hours.

You are moving so fast through these videos! 🤓😎

I know you're well on the way Douglas 😎

Awesome, thanks again!

Thanks Bayram!

The Model that we are updating is a Struct. Structs are based on VALUES and not INSTANCES... When you "update" a Class, you can access the instance of the class and change values inside. However, since Structs don't have instances and are based directly on their values, you can't change a value in a struct, otherwise it would be a different struct. Instead, we can "mutate" the struct, which is really just creating a new Struct and replacing it with the current one. In the update function, we are creating a totally new Struct, however, we are initializing it with most of the values from the current/previous struct.

You’re welcome 😊

lehanas! Thanks for watching :)

Thanks for watching Faik 🥳

Hi April! Thanks for watching. You should be able to update the updateItem function with whatever parameters you want to change. You just need to return a new struct (Model) with the correct values!

@@SwiftfulThinking Thank you.

Hahaha I think you're right -____-

@@SwiftfulThinking OH he's right

You could add a "selectedItem" variable into the ViewModel!

Hey, thanks for watching! I'm a bit confused about your question. Just to confirm, the ViewModel here is initialized at the app launch using @StateObject and then passed around the app using @EnvironmentObject. We are not destroying and recreating it during the life cycle.

As for the second part of your question, yes I would make more ViewModels if we added more Views (assuming the new Views didn't share the same ViewModel logic). I would also note that this is a beginner level course and it's much easier to learn/follow by creating ViewModels within the structs that need them. I have not covered Protocols or Dependency Injection yet, but if you know how to use these to make the VM initialization more efficient, then you should definitely do that!

@@SwiftfulThinking Yeah exactly, by initializing it once at app launch you dont have to worry about it. The question is irrelevant to this sorry! All I was curious about is how the view models escalate with app complexity such as adding more models & views, do you tend to use one single viewmodel or multiple viewmodels? Or just depends on the situation?

@@sgtpotatoe Complex apps usually use multiple ViewModels. If you had one for the entire app, it would end up being very long and confusing to work with. A rough estimate could be one ViewModel for each screen. Apps with more advanced architecture might also have some "global" ObservableObjects that are more high level than a ViewModel, but function in the same way.

@@SwiftfulThinking Thanks a lot! Really helpful!

You are haha 😁

2 of them can, if you import SwiftUI into the view model class file , but I am really struggling w/ the 3rd, ie saveButtonPressed .... bc of the @Environment call.

The view requires a ListViewModel to be in the environment or it won’t compile. There’s a video on @EnvironmentObject in the Bootcamp playlist 👍

Had the exact same issue. Thanks!

Im SwiftUI, data normally flows from parent to child. You only need a binding if the child needs to update the parent.

@@SwiftfulThinking got it thanks! 🫡

Hey Pierre! I don't have any good references for this, sorry.

Hey Paul, yes you could definitely do that! You would need to add the fields to the data model and then sort the items before setting self.items = savedItems. I cover the basics of sorting here: ukposts.info/have/v-deo/fl2YiZCxq4aFyH0.html and a more advanced example in the Crypto App tutorial here: ukposts.info/have/v-deo/kaKZe35vhKGis5c.html

@@SwiftfulThinking thanks for the quick reply. I’ll check those out tonight

The initializer of the ForEach that uses a Range (what you’re using here) specifically says it’s only for an array with a “constant” range. So if you’re changing the number of items in the array, it’s better not to use that. If you’re looping on Items, you can also make a function to find the Item’s index using array.firstIndex(where:)

@@SwiftfulThinking Alright good tip thanks a lot ! Now I'm still looking how I can change the values of all other instances (so all except the index)

Hey Craig, yes, I'm happy to answer questions. It might be better to finish the course first though. I think things might make more sense as we wrap up and test the application in the next few videos!

You can add .swipeAction modifier on foreach row, and add a button with navLink to a new view.

You can add more properties within the Model and update it the same way we are updating the completion boolean.

Because isCompleted is a constant property, you can’t change it outside of the model struct. That’s why he created an additional initializer and put it in a function inside of model struct to remain the same id and title during initialization for existing item.

@@CinematicAdventureOne If we know isCompleted is a property that will change, can't we just declare it with var to avoid creating an additional initializer? What's the benefit of creating it as a constant property?

@@lolrie same questions

We are!! I love meeting fellow penn staters. That's awesome.... you're question is fairly specific. If you're using a NavigationLink, the button would then navigate to the next screen, so having the circle animation would be pointless. There are probably better ways to optimize if that's the situation.

@@SwiftfulThinking if you look at the Apple Music app for example. In a list of songs, if you tap the button on the far right, it adds the song to your playlist but if you tap anywhere els on the cell, it plays the music. I wanted to implement the same feature in my app where if you where to tap on a button on the far right an action occurs like subscribe but if you were to tap any where else on the cell it takes you to a detailed view of the cell.

@@SwiftfulThinking I followed these steps and at around 18 minutes into the video creating the add function into the view model, I'm getting a couple of errors.

no exact matches in call to instance method 'append'

@@rasheed1andrew It sounds like you might have made a typo somewhere. The full source code is available on my Github if you want to compare: github.com/SwiftfulThinking

Yes exactly. There is more than one way to do this but I find this to be a safe approach for beginners 👍

You can either make the cell a Button or add a .background(Color.black.opacity(0.001) to make the area tappable

It’s included in this one: ukposts.info/have/v-deo/rJuAoo5-ZKl_zKc.html

@@SwiftfulThinking Thanks for the quick reply. My confusion was caused by your channel home page. On your channel home page, the SwiftUI Bootcamp (Beginner Level) lists only 11 videos in the scrolling carousel . I have now seen the whole playlist which has more than 50 videos! This explains why I could not understand several times when you referenced back to a Bootcamp video. I have a lot more videos to watch!

Hey great question! I use SwiftUI files when I need the preview section at the bottom because it comes with the template Previews (for the Views). But I use Swift file when I don't need the preview (for everything other than the View). The different is just the template code that comes in the starting file. You can actually edit either of them to be the same thing haha

I think you can create a new viewModel just for AddView to play with the function logic. But adding these function and logic to ListViewModel will make it a bit complex and confusing as it’s a beginner tutorial.

Hi Craig! That's exactly why I started with this very simple app. I think a lot of people overcomplicated the ViewModel. All we are really doing is separating the logic for the screen (which is in the View) from the logic for the data behind the screen (which is in the ViewModel). Definitely let me know if you have any questions!

@@SwiftfulThinking that part I understand - what gets me is the alert processing - you have the .alert on the ScrollView but I don't understand why it fires or what its purpose is when the text is < 3 characters keyed in and that is triggered by the button action (saveButtonPressed). so does the modifier on the ScrollView simply define an alert? i don't get it obviously. thanks for helping!

I finally got it - had to re-watch the Alert video! your videos are like a reference libraray!

@@dr.craigcurphey4829 Haha that's great to hear. I tried to structure the courses so that I never use anything in a video that I haven't previously covered already :)

I think the compiler in Xcode 13 is just super slow compared to Xcode 12 (which is what I used when making this video). Hopefully they fix it in a future release.

Eventually there would be a performance loss because you're going to load all of this extra, non-essential code into every View. However, the bigger worry would just be organization. You can't have 2 of the same Type of objects in the same Environment of a view, and you often don't want all of your Views to have access to all of your services.

@@SwiftfulThinking That makes sense. Thank you!

having the same problem here :/

i was wondering why it works for me without Combine but there is an answer from ChatGPT My Question was: but it works fine with foundation. You're correct! In your case, the @Published property wrapper is working fine without explicitly importing the Combine framework because SwiftUI implicitly imports Combine when used with @Published, even though you haven't imported Combine explicitly in your TodoViewModel. SwiftUI's @Published property wrapper uses Combine under the hood to provide observable behavior for your properties. This integration allows for automatic change notifications and data binding between your view model and SwiftUI views. So, while you don't need to explicitly import Combine in your TodoViewModel file, the @Published property wrapper will still leverage Combine functionality for publishing property changes. Your TodoViewModel class should work smoothly with @Published as you've implemented it. If you have any more questions or need further clarification, feel free to ask!

hm i guess we added init to not only toggle the completion, it makes sense

it's much safer to make it let and there is some methods that you can toggle isCompleted without necessarily making it var. you watch swift course there is some keynotes ukposts.info/have/v-deo/n4J8oKapjKBeqmw.htmlsi=9Nl8CrdJCH6P9Hq7&t=408

Hello! I will try to make a diagram in the Github repo soon. The simple structure is that the ViewModel loads the data and then sends it to the View to display on the screen!

@@SwiftfulThinking what I mean is that you create an struct and the in de main view you declare a variable and sign to the struct, but if you create another view you use instead of var test = struct() you say var test : struct is that the same information??

the data is "inside the struct or the var test?

Hi Hanjun! Yea I need to invest in one 😩 Sorry about that.

Because the Model is a Struct and not a Class. Structs are based on values, so in order to change the data inside a Struct, we need to "mutate" it or create a new one with updated information. If our model was a Class, then we could do that..

@@SwiftfulThinking Thanks! Your explanations are amazing.

Hi Shreyaansh! I included it within the .sheet() video. The presentationMode is just an environment variable that understands what screen is currently showing on the app. We use it to dismiss the current screen. ukposts.info/have/v-deo/nJSjZ3tno2qYqoU.html