add sugar for passing Action as View callback

Author: square-tomb

Samples/TicTacToe/Sources/Authentication/LoginScreen.swift

@@ -44,10 +44,10 @@ struct LoginScreen: SwiftUIScreen, Equatable {
                     get: \.password,
                     set: Action.passwordUpdated
                 ),
-                onCommit: { model.value.actionSink.send(.login) }
+                onCommit: model.action(.login)
             )
 
-            Button("Login", action: { model.value.actionSink.send(.login) })
+            Button("Login", action: model.action(.login))
         }
         .frame(maxWidth: 400)
     }

WorkflowSwiftUI/Sources/ObservableValue.swift

@@ -104,3 +104,14 @@ public final class ObservableValue<Value>: ObservableObject {
         return subject.removeDuplicates(by: isDuplicate).eraseToAnyPublisher()
     }
 }
+
+#if canImport(UIKit)
+
+public extension ObservableValue where Value: SwiftUIScreen {
+    func action(_ action: Value.Action) -> () -> Void {
+        // TODO: Should this closure capture the current `actionSink` instead?
+        { [weak self] in self?.value.actionSink.send(action) }
+    }
+}
+
+#endif