@Observable in SwiftUI

The @Observable macro, introduced at WWDC 2023 and supported from iOS17 onwards, it replaces ObservableObject and @Published properties. It automatically triggers SwiftUI view updates when any changes occurs.

Let’s move to the code

Before @Observable macro

// View
struct ContentView: View {
    @StateObject var vm: ViewModel = ViewModel()
    var body: some View {
        VStack {
            Text("Hello, world \(vm.count)")
            Button {
                vm.count += 1
            } label: {
                Text("Click me")
            }
        }
        .padding()
    }
}
// Viewmodel
final class ViewModel: ObservableObject {
    @Published var count: Int =  0
}

After implementing @Observable macro

// View
struct ContentView: View {
    let vm: ViewModel = ViewModel()
    var body: some View {
        VStack {
            Text("Hello, world \(vm.count)")
            Button {
                vm.count += 1
            } label: {
                Text("Click me")
            }
        }
        .padding()
    }
}
// Viewmodel
@Observable
final class ViewModel {
   var count: Int =  0
}

Let see the output

Simple and easy right???? 😉

If you right click @Observable macro and click on Refactor->Inline Macro then you see below code.

final class ViewModel {
    @ObservationTracked var count: Int =  0
    
    
    @ObservationIgnored private let _$observationRegistrar = Observation.ObservationRegistrar()
    
    internal nonisolated func access<Member>(
        keyPath: KeyPath<ViewModel , Member>
    ) {
        _$observationRegistrar.access(self, keyPath: keyPath)
    }
    
    internal nonisolated func withMutation<Member, MutationResult>(
        keyPath: KeyPath<ViewModel , Member>,
        _ mutation: () throws -> MutationResult
    ) rethrows -> MutationResult {
        try _$observationRegistrar.withMutation(of: self, keyPath: keyPath, mutation)
    }
}

extension ViewModel: Observation.Observable {
}

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Thanks for reading, Happy Coding 💻