Implemented 'OnAppFirstRun' View Modifier

Sources/SwiftfulUI/ViewModifiers/OnAppFirstRunModifier.swift

@@ -0,0 +1,43 @@
+//
+//  OnAppFirstRunModifier.swift
+//
+//
+//  Created by Ricky Stone on 17/11/2023.
+//
+
+import SwiftUI
+
+struct OnAppFirstRunModifier: ViewModifier {
+    let action: @MainActor () -> Void
+
+    func body(content: Content) -> some View {
+        content
+            .onAppear {
+                FirstRunManager.shared.executeFirstRunAction(action: action)
+            }
+    }
+}
+
+extension View {
+    public func onAppFirstRun(perform action: @MainActor @escaping () -> Void) -> some View {
+        modifier(OnAppFirstRunModifier(action: action))
+    }
+}
+
+class FirstRunManager {
+    static let shared = FirstRunManager()
+    private var hasFirstRunActionExecuted = false
+
+    private init() {}
+
+    func executeFirstRunAction(action: () -> Void) {
+        if UserDefaults.standard.bool(forKey: "appHasBeenLaunchedOnce") || hasFirstRunActionExecuted {
+            return
+        }
+
+        action()
+        hasFirstRunActionExecuted = true
+        UserDefaults.standard.set(true, forKey: "appHasBeenLaunchedOnce")
+    }
+}
+