swiftui-observation

SwiftUI Observation (iOS 17+)

Overview

The @Observable macro (Observation framework) replaces ObservableObject/@Published. Views automatically track only the properties they actually read, so re-rendering becomes fine-grained instead of invalidating on every @Published change.

When to use

• New SwiftUI view models or app state on iOS 17+
• Migrating off ObservableObject, @Published, @StateObject, @ObservedObject, @EnvironmentObject
• Excess re-renders / performance from coarse @Published invalidation
• Two-way bindings to a reference-type model (@Bindable)

Property-wrapper map (old → new)

Example

@Observable final class ProfileModel {
    var name = ""
    var isSaving = false
    // No @Published — stored properties are observed automatically.
    @ObservationIgnored private var cache: [String: Data] = [:]   // not tracked
}

struct ProfileView: View {
    @State private var model = ProfileModel()    // this view OWNS the model

    var body: some View {
        @Bindable var model = model              // local bindable for $ bindings
        Form {
            TextField("Name", text: $model.name) // two-way binding
            if model.isSaving { ProgressView() } // only views reading isSaving re-render
        }
        .environment(model)                      // inject to descendants
    }
}

struct ChildView: View {
    @Environment(ProfileModel.self) private var model   // typed environment injection
    var body: some View { Text(model.name) }
}

Common mistakes