Implement ObservedDependency

README.md

@@ -26,6 +26,7 @@ AppState is a Swift Package that simplifies the management of application state
 ### Dependency Management
 
 - **Dependency:** Struct for encapsulating dependencies within the app's scope.
+- 🍎 **ObservedDependency:** Struct for encapsulating dependencies within the app's scope. Backed by an `@ObservedObject` to publish changes to SwiftUI views.
 - **Scope:** Represents a specific context within an app, defined by a unique name and ID.
 
 ### Property Wrappers
@@ -300,7 +301,7 @@ In this case, ContentView has access to the networkService dependency and can us
 
 ### Using Dependency with ObservableObject
 
-When your dependency is an `ObservableObject`, any changes to it will automatically update your SwiftUI views. Make sure your service conforms to the `ObservableObject` protocol. To do this, you should not use the `@AppDependency` property wrapper, but instead use the `@ObservedObject` property wrapper. 
+When your dependency is an `ObservableObject`, any changes to it will automatically update your SwiftUI views. Make sure your service conforms to the `ObservableObject` protocol. To do this, you should not use the `@AppDependency` property wrapper, but instead use the `@ObservedDependency` property wrapper. 
 
 Here's an example:
 
@@ -318,7 +319,7 @@ extension Application {
 }
 
 struct ContentView: View {
-    @ObservedObject var dataService = Application.dependency(\.dataService)
+    @ObservedDependency(\.dataService) private var dataService
 
     var body: some View {
         List(dataService.data, id: \.self) { item in

Sources/AppState/PropertyWrappers/Dependency/ObservedDependency.swift

@@ -0,0 +1,49 @@
+#if !os(Linux) && !os(Windows)
+import SwiftUI
+
+/// The `@ObservedDependency` property wrapper is a feature provided by AppState, intended to simplify dependency handling throughout your application. It makes it easy to access, share, and manage dependencies in a neat and Swift idiomatic way. It works the same as `@AppDependency`, but comes with the power of the `@ObservedObject` property wrapper.
+@propertyWrapper public struct ObservedDependency<Value>: DynamicProperty where Value: ObservableObject {
+    /// Path for accessing `ObservedDependency` from Application.
+    private let keyPath: KeyPath<Application, Application.Dependency<Value>>
+
+    @ObservedObject private var observedObject: Value
+
+    private let fileID: StaticString
+    private let function: StaticString
+    private let line: Int
+    private let column: Int
+
+    /// Represents the current value of the `ObservedDependency`.
+    public var wrappedValue: Value { observedObject }
+
+    /// A binding to the `ObservedDependency`'s value, which can be used with SwiftUI views.
+    public var projectedValue: ObservedObject<Value>.Wrapper { $observedObject }
+
+    /**
+     Initializes the AppDependency with a `keyPath` for accessing `Dependency` in Application.
+
+     - Parameter keyPath: The `KeyPath` for accessing `Dependency` in Application.
+     */
+    public init(
+        _ keyPath: KeyPath<Application, Application.Dependency<Value>>,
+        _ fileID: StaticString = #fileID,
+        _ function: StaticString = #function,
+        _ line: Int = #line,
+        _ column: Int = #column
+    ) {
+        self.keyPath = keyPath
+        self.fileID = fileID
+        self.function = function
+        self.line = line
+        self.column = column
+
+        self.observedObject = Application.dependency(
+            keyPath,
+            fileID,
+            function,
+            line,
+            column
+        )
+    }
+}
+#endif

Tests/AppStateTests/ObservedDependencyTests.swift

@@ -0,0 +1,53 @@
+#if !os(Linux) && !os(Windows)
+import SwiftUI
+import XCTest
+@testable import AppState
+
+fileprivate class ObservableService: ObservableObject {
+    @Published var count: Int
+
+    init() { 
+        count = 0
+    }
+}
+
+fileprivate extension Application {
+    var test: Dependency<String> {
+        dependency("!!!")
+    }
+
+    var observableService: Dependency<ObservableService> {
+        dependency(ObservableService())
+    }
+}
+
+fileprivate struct ExampleDependencyWrapper {
+    @ObservedDependency(\.observableService) var service
+
+    func test() {
+        service.count += 1
+
+        _ = Picker("", selection: $service.count, content: EmptyView.init)
+    }
+}
+
+final class ObservedDependencyTests: XCTestCase {
+    override class func setUp() {
+        Application.logging(isEnabled: true)
+    }
+
+    override class func tearDown() {
+        Application.logger.debug("ObservedDependencyTests \(Application.description)")
+    }
+
+    func testDependency() {
+        let example = ExampleDependencyWrapper()
+
+        XCTAssertEqual(example.service.count, 0)
+
+        example.test()
+
+        XCTAssertEqual(example.service.count, 1)
+    }
+}
+#endif