Add modifyingIds to the Readme

Author: mdb1

README.md

@@ -19,6 +19,8 @@ There is an Example app available [here](https://github.com/mdb1/ViewStateContro
     * [Changing Loading types](https://github.com/mdb1/ViewStateController#changing-loading-types)
     * [Using Custom Views](https://github.com/mdb1/ViewStateController#using-custom-views)
   * [Demo](https://github.com/mdb1/ViewStateController#demo-loading-type-options)
+  * [ModifyingIds](https://github.com/mdb1/ViewStateController#modifying-ids)
+      * [Demo](https://github.com/mdb1/ViewStateController#demo-modifying-ids)
 * [Toasts](https://github.com/mdb1/ViewStateController#toast)
   * [Examples with code samples](https://github.com/mdb1/ViewStateController#examples-with-code-samples-1)
 
@@ -283,6 +285,80 @@ In this video, we are tweaking around some properties and pass them to the `with
 
 The app used for this video can be downloaded from [this repository](https://github.com/mdb1/ViewStateControllerExampleApp). 
 
+## Modifying Ids
+
+The ViewStateController object also provided an array of Strings (modifyingIds):
+
+```swift
+/// Use this property when you need to make changes to specific parts of your view.
+/// Example: When you want to display a ProgressView while deleting an item from a list.
+public var modifyingIds: [String]?
+```
+
+It's usage is really simple:
+
+```swift
+func listView(_ pokemons: [Pokemon]) -> some View {
+    VStack {
+        ForEach(pokemons) { pokemon in
+            HStack {
+                Text(pokemon.name)
+                Spacer()
+                trailingView(for: pokemon.id)
+            }
+            Divider()
+        }
+    }
+}
+
+@ViewBuilder
+func trailingView(for id: String) -> some View {
+
+    if let modifyingIds = controller.modifyingIds, modifyingIds.contains(id) {
+        // If the id is in the `modifyingIds` array, it means someone is modifying it.
+        // So we display a loading indicator.
+        ProgressView()
+    } else {
+        // Otherwise, we display a remove button.
+        Button("Remove", role: .destructive) {
+            Task {
+                // Tapping the button triggers an async call to remove the pokemon.
+                await removePokemon(id: id)
+            }
+        }
+    }
+}
+
+func removePokemon(id: String) async {
+    withAnimation {
+        // We add the `id` to the array.
+        controller.modifyingIds = (controller.modifyingIds ?? []) + [id]
+    }
+    // We simulate an async call to the backend. (1 second sleep)
+    try? await Task.sleep(nanoseconds: 1_000_000_000)
+    if let latestInfo = controller.latestInfo {
+        let updatedInfo = latestInfo.filter { pokemon in
+            pokemon.id != id
+        }
+        withAnimation {
+            // Then we update the state
+            controller.setState(.loaded(updatedInfo))
+            // And remove the id from the modifying array
+            controller.modifyingIds?.removeAll(where: { $0 == id })
+        }
+    }
+}
+
+struct Pokemon: Identifiable {
+    let id: String
+    let name: String
+}
+```
+
+### Demo: Modifying Ids
+
+https://user-images.githubusercontent.com/5333984/225748007-ff1e0fed-8e80-4b73-9f3e-d83b7edc3064.mov
+
 # Toasts
 
 Similar to the LoadingModifier, there is also a [ToastModifier](https://github.com/mdb1/ViewStateController/blob/main/Sources/ViewStateController/ViewModifiers/ToastModifier.swift) that let's you present toast/snack bars/custom views in the screen with a set of configurable parameters.