Views in SwiftUI are thrown away and recreated regularly. When this happens, the entire view struct is initialized all over again. Because of this, any values that you create in a SwiftUI view are reset to their default values unless you've marked these values using @State. This means that if you declare a view that creates its own @ObservedObject instance, that instance is replaced every time SwiftUI decides that it needs to discard and redraw that view. If you want to see what I mean, try running the following SwiftUI view: class DataSource: ObservableObject { @Published var counter = 0...

In SwiftUI, views can be driven by an @Published property that's part of an ObservableObject. If you've used SwiftUI and @Published before, following code should look somewhat familiar to you: class DataSource: ObservableObject { @Published var names = [String]() } struct NamesList: View { @ObservedObject var dataSource: DataSource var body: some View { List(dataSource.names, id: \.self) { name in Text(name) } } } Whenever the DataSource object's names array changes, NamesList will be automatically redrawn. That's great. Now imagine that our list of names is retrieved through the network somehow and we want to load the list of names in...

If you have spent some time with SwiftUI or if you have watched the WWDC videos on SwiftUI this year, you may have noticed that views in SwiftUI have a property called body of type some View. The some keyword is new in Swift 5.1 and it’s part of a feature called opaque result types (SE-0244). What is this some keyword then? And how can you use it in your code? I aim to answer these questions in this blog post. We’ll first explore what opaque result types are, and more specifically what problem they solve. Next, we’ll look at...