SwiftUI View Lifecycle Methods → onChange

.swift

import SwiftUI

struct ContentView: View {
    
    // tracking changes of this property via 'onChange' method
    @State private var notificationsEnabled = false
    
    var body: some View {
        Toggle("Notifications", isOn: $notificationsEnabled)
            .padding()
            .font(.title)
            .onChange(of: notificationsEnabled) { newValue in
                print(newValue ? "Notifications Enabled" : "Notifications Disabled")
            }
    }
}