Provide a convenience for creating a change handler that just updates

some external state using a binding.

Author: lukeredpath

Demo Project/ResponsiveTextFieldDemo/ContentView.swift

@@ -90,9 +90,9 @@ struct ContentView: View {
                         isSecure: hidePassword,
                         firstResponderDemand: $passwordResponderDemand.animation(),
                         configuration: .combine(.password, .lastOfChain),
-                        onFirstResponderStateChanged: FirstResponderStateChangeHandler { isFirstResponder in
-                            isPasswordFirstResponder = isFirstResponder
-                        }.animation(),
+                        onFirstResponderStateChanged: FirstResponderStateChangeHandler
+                            .updates($isPasswordFirstResponder)
+                            .animation(),
                         handleReturn: { passwordResponderDemand = .shouldResignFirstResponder },
                         handleDelete: {
                             if $0.isEmpty {

Sources/ResponsiveTextField/ResponsiveTextField.swift

@@ -204,6 +204,20 @@ public struct FirstResponderStateChangeHandler {
     }
 }
 
+extension FirstResponderStateChangeHandler {
+    /// Returns a change handler that updates a `Bool` binding with the `isFirstResponder`
+    /// value whenever it changes.
+    ///
+    /// - Parameters:
+    ///     - binding: A binding to some Boolean state property that should be updated.
+    ///
+    public static func updates(_ binding: Binding<Bool>) -> Self {
+        .init { isFirstResponder in
+            binding.wrappedValue = isFirstResponder
+        }
+    }
+}
+
 /// Represents a request to change the text field's first responder state.
 ///
 public enum FirstResponderDemand: Equatable {