SwiftUI State Management: Avoiding Unnecessary View Updates

Use `@StateObject` for creating ObservableObject instances within a view, `@ObservedObject` for receiving them from parent views, and `@State` for simple UI-specific values. This creates a clear hierarchy where data flows down and actions flow up.

class UserStore: ObservableObject {
    @Published var users: [User] = []
    @Published var isLoading = false
}

struct ContentView: View {
    @StateObject private var userStore = UserStore()
    @State private var showingSheet = false
    
    var body: some View {
        NavigationView {
            VStack {
                if userStore.isLoading {
                    ProgressView()
                } else {
                    UserListView(userStore: userStore)
                }
            }
            .sheet(isPresented: $showingSheet) {
                AddUserView(userStore: userStore)
            }
        }
    }
}

struct UserListView: View {
    @ObservedObject var userStore: UserStore
    
    var body: some View {
        List(userStore.users) { user in
            Text(user.name)
        }
    }
}

Why This is a Best Practice

This pattern prevents unnecessary object recreation during view updates, ensures proper memory management, and creates predictable data flow. `@StateObject` maintains object lifecycle tied to view lifecycle, while `@ObservedObject` allows sharing state between views without ownership transfer.

class UserStore: ObservableObject {
    @Published var users: [User] = []
    @Published var isLoading = false
}

struct ContentView: View {
    @StateObject private var userStore = UserStore()
    @State private var showingSheet = false
    
    var body: some View {
        NavigationView {
            VStack {
                if userStore.isLoading {
                    ProgressView()
                } else {
                    UserListView(userStore: userStore)
                }
            }
            .sheet(isPresented: $showingSheet) {
                AddUserView(userStore: userStore)
            }
        }
    }
}

struct UserListView: View {
    @ObservedObject var userStore: UserStore
    
    var body: some View {
        List(userStore.users) { user in
            Text(user.name)
        }
    }
}

Why This is a Best Practice

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SwiftUI State Management: Avoiding Unnecessary View Updates

Why This is a Best Practice