[wip exploration] move screen currency to ViewEnvironmentUI

ViewEnvironmentUI/README.md

@@ -1,6 +1,7 @@
 # ViewEnvironmentUI
 
-`ViewEnvironmentUI` provides a means to propagate a `ViewEnvironment` through a hierarchy of object nodes.
-
-Support for propagation of `ViewEnvironment` through `UIViewController`s and `UIView`s is provided by this framework.
+`ViewEnvironmentUI` provides some fundamental types to build UI:
 
+- A means to propagate a `ViewEnvironment` through a hierarchy of object nodes, and an implementation of propagation through `UIViewController`s and `UIView`s.
+- The `ViewDescription` type, a declarative way to represent a view controller.
+- The `Screen` protocol, to create your own types that can produce a `ViewDescription` from a `ViewEnvironment`.

WorkflowUI/Sources/Screen/AnyScreen/AnyScreen.swift → ViewEnvironmentUI/Sources/Screen/AnyScreen.swift

@@ -17,6 +17,7 @@
 #if canImport(UIKit)
 
 import UIKit
+import ViewEnvironment
 
 public struct AnyScreen: Screen {
     /// The original screen, retained for debugging
@@ -42,12 +43,4 @@ extension Screen {
     }
 }
 
-// MARK: SingleScreenContaining
-
-extension AnyScreen: SingleScreenContaining {
-    public var primaryScreen: any Screen {
-        wrappedScreen
-    }
-}
-
 #endif

WorkflowUI/Sources/Screen/Screen.swift → ViewEnvironmentUI/Sources/Screen/Screen.swift

@@ -17,6 +17,7 @@
 #if canImport(UIKit)
 
 import UIKit
+import ViewEnvironment
 
 /// Screens are the building blocks of an interactive application.
 ///

WorkflowUI/Sources/ViewControllerDescription/UIViewController+Extensions.swift → ViewEnvironmentUI/Sources/ViewControllerDescription/UIViewController+Extensions.swift

@@ -17,6 +17,7 @@
 #if canImport(UIKit)
 
 import UIKit
+import ViewEnvironment
 
 extension UpdateChildScreenViewController where Self: UIViewController {
     /// Updates the view controller at the given `child` key path with the

WorkflowUI/Sources/ViewControllerDescription/ViewControllerDescription.swift → ViewEnvironmentUI/Sources/ViewControllerDescription/ViewControllerDescription.swift

@@ -18,7 +18,6 @@
 
 import UIKit
 import ViewEnvironment
-@_spi(ViewEnvironmentWiring) import ViewEnvironmentUI
 
 /// A ViewControllerDescription acts as a "recipe" for building and updating a specific `UIViewController`.
 /// It describes how to _create_ and later _update_ a given view controller instance, without creating one

WorkflowUI/Tests/AdaptedEnvironmentScreenTests.swift → ViewEnvironmentUI/Tests/AdaptedEnvironmentScreenTests.swift

@@ -17,8 +17,9 @@
 #if canImport(UIKit)
 
 import UIKit
+import ViewEnvironment
+import ViewEnvironmentUI
 import XCTest
-@testable import WorkflowUI
 
 class AdaptedEnvironmentScreenTests: XCTestCase {
     func test_wrapping() {
@@ -53,10 +54,12 @@ fileprivate struct TestScreen: Screen {
     func viewControllerDescription(environment: ViewEnvironment) -> ViewControllerDescription {
         read(environment)
 
-        return ViewController.description(for: self, environment: environment)
+        return ViewControllerDescription(
+            environment: environment,
+            build: UIViewController.init,
+            update: { _ in }
+        )
     }
-
-    private class ViewController: ScreenViewController<TestScreen> {}
 }
 
 #endif

WorkflowUI/Tests/UIViewControllerExtensionTests.swift → ViewEnvironmentUI/Tests/UIViewControllerExtensionTests.swift

@@ -17,8 +17,9 @@
 #if canImport(UIKit)
 
 import UIKit
+import ViewEnvironment
+import ViewEnvironmentUI
 import XCTest
-@testable import WorkflowUI
 
 class UIViewControllerExtensionTests: XCTestCase {
     func test_update_viewNotLoaded() {

WorkflowUI/Tests/ViewControllerDescriptionTests.swift → ViewEnvironmentUI/Tests/ViewControllerDescriptionTests.swift

@@ -16,12 +16,10 @@
 
 #if canImport(UIKit)
 
+import ViewEnvironment
+import ViewEnvironmentUI
 import XCTest
 
-import ReactiveSwift
-import Workflow
-@testable import WorkflowUI
-
 fileprivate class BlankViewController: UIViewController {}
 
 @objc fileprivate protocol MyProtocol {
@@ -179,30 +177,6 @@ class ViewControllerDescriptionTests: XCTestCase {
             XCTAssertEqual(environment[TestKey.self], 2)
         }
     }
-
-    func test_screenViewController() {
-        // Make sure ScreenViewController<T>.description(for:) generates a correct view controller
-        // description
-
-        struct MyScreen: Screen {
-            func viewControllerDescription(environment: ViewEnvironment) -> ViewControllerDescription {
-                MyScreenViewController.description(for: self, environment: environment)
-            }
-        }
-
-        final class MyScreenViewController: ScreenViewController<MyScreen> {}
-
-        let screen = MyScreen()
-        let description = screen.viewControllerDescription(environment: .empty)
-
-        let viewController = description.buildViewController()
-        XCTAssertTrue(type(of: viewController) == MyScreenViewController.self)
-
-        XCTAssertTrue(description.canUpdate(viewController: viewController))
-
-        let viewControllerAgain = description.buildViewController()
-        XCTAssertFalse(viewController === viewControllerAgain)
-    }
 }
 
 class ViewControllerDescription_KindIdentifierTests: XCTestCase {

WorkflowUI/Sources/Screen/AnyScreen+SingleScreenContaining.swift

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2020 Square Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#if canImport(UIKit)
+
+extension AnyScreen: SingleScreenContaining {
+    public var primaryScreen: any Screen {
+        wrappedScreen
+    }
+}
+
+#endif

WorkflowUI/Tests/ScreenViewControllerTests.swift

@@ -0,0 +1,33 @@
+#if canImport(UIKit)
+
+import UIKit
+import WorkflowUI
+import XCTest
+
+final class ScreenViewControllerTests: XCTestCase {
+    func test_screenViewController() {
+        // Make sure ScreenViewController<T>.description(for:) generates a correct view controller
+        // description
+
+        struct MyScreen: Screen {
+            func viewControllerDescription(environment: ViewEnvironment) -> ViewControllerDescription {
+                MyScreenViewController.description(for: self, environment: environment)
+            }
+        }
+
+        final class MyScreenViewController: ScreenViewController<MyScreen> {}
+
+        let screen = MyScreen()
+        let description = screen.viewControllerDescription(environment: .empty)
+
+        let viewController = description.buildViewController()
+        XCTAssertTrue(type(of: viewController) == MyScreenViewController.self)
+
+        XCTAssertTrue(description.canUpdate(viewController: viewController))
+
+        let viewControllerAgain = description.buildViewController()
+        XCTAssertFalse(viewController === viewControllerAgain)
+    }
+}
+
+#endif