Example code in README

Examples/SignUpDemo/Sources/Onboarding/SignUpViewModel.swift

@@ -12,6 +12,45 @@ public enum SignUpUserAction: Sendable {
     case signedUp(SignedUpUser)
 }
 
+// MARK: InputFromView
+public extension SignUpViewModel {
+	/// User-event publishers the view streams in.
+	struct InputFromView {
+		public let name: AnyPublisher<String, Never>
+		public let email: AnyPublisher<String, Never>
+		public let submitTrigger: AnyPublisher<Void, Never>
+
+		public init(
+			name: AnyPublisher<String, Never>,
+			email: AnyPublisher<String, Never>,
+			submitTrigger: AnyPublisher<Void, Never>
+		) {
+			self.name = name
+			self.email = email
+			self.submitTrigger = submitTrigger
+		}
+	}
+}
+
+// MARK: Output
+public extension SignUpViewModel {
+	/// Reactive bindings the view installs.
+	struct Output {
+		/// Drives the Sign Up button's `isEnabled` (`isFormValid && !isLoading`).
+		public let isSubmitEnabled: AnyPublisher<Bool, Never>
+
+		/// `true` while the sign-up service call is in flight. The view
+		/// reflects this on a `UIActivityIndicatorView` overlaid on the
+		/// submit button.
+		public let isLoading: AnyPublisher<Bool, Never>
+	}
+}
+public extension SignUpViewModel.Output {
+	var loadingText: AnyPublisher<String, Never> {
+		isLoading.map { $0 ? "" : "Sign Up" }.eraseToAnyPublisher()
+	}
+}
+
 /// Drives `SignUpView`: validates the (very loose) name + email rules,
 /// gates the submit button, and on tap calls the injected service. The
 /// returned user is forwarded as `.signedUp` to the parent coordinator.
@@ -20,13 +59,14 @@ public final class SignUpViewModel: BaseViewModel<
     SignUpViewModel.InputFromView,
     SignUpViewModel.Output
 > {
-    private let service: SignUpServicing
+	private let service: SignUpServicing
 
-    public init(service: SignUpServicing) {
-        self.service = service
-        super.init()
-    }
+	public init(service: SignUpServicing) {
+		self.service = service
+		super.init()
+	}
 
+	// MARK: BaseViewModel Overrides
     override public func transform(input: Input) -> Output {
         // Track the in-flight state of the sign-up call so the view can show
         // a spinner and disable the submit button while waiting.
@@ -70,39 +110,3 @@ public final class SignUpViewModel: BaseViewModel<
         )
     }
 }
-
-public extension SignUpViewModel.Output {
-    var loadingText: AnyPublisher<String, Never> {
-        isLoading.map { $0 ? "" : "Sign Up" }.eraseToAnyPublisher()
-    }
-}
-
-public extension SignUpViewModel {
-    /// User-event publishers the view streams in.
-    struct InputFromView {
-        public let name: AnyPublisher<String, Never>
-        public let email: AnyPublisher<String, Never>
-        public let submitTrigger: AnyPublisher<Void, Never>
-
-        public init(
-            name: AnyPublisher<String, Never>,
-            email: AnyPublisher<String, Never>,
-            submitTrigger: AnyPublisher<Void, Never>
-        ) {
-            self.name = name
-            self.email = email
-            self.submitTrigger = submitTrigger
-        }
-    }
-
-    /// Reactive bindings the view installs.
-    struct Output {
-        /// Drives the Sign Up button's `isEnabled` (`isFormValid && !isLoading`).
-        public let isSubmitEnabled: AnyPublisher<Bool, Never>
-
-        /// `true` while the sign-up service call is in flight. The view
-        /// reflects this on a `UIActivityIndicatorView` overlaid on the
-        /// submit button.
-        public let isLoading: AnyPublisher<Bool, Never>
-    }
-}

README.md

@@ -3,6 +3,120 @@
 # NVC: NanoViewController
 An **extremely** opinionated UIKit architecture built on top of MVVM-C allowing you to create `UIViewController`s declaratively with as little as a single line of code.
 
+## Show me code
+```swift
+// MARK: NanoViewController
+public final class SignUpScene: Scene<SignUpView> { // 🤯 3 lines VC! 
+    public static let title = "Sign Up"
+}
+
+// MARK: View
+public final class SignUpView: UIView {
+	private lazy var nameField: 	UITextField 			= { ... }()
+	private lazy var emailField: 	UITextField 			= { ... }()
+	private lazy var submitButton: 	UIButton 				= { ... }()
+	private lazy var spinner: 		UIActivityIndicatorView = { ... }()
+}
+extension SignUpView: ViewModelled {
+    public typealias ViewModel = SignUpViewModel
+
+    public var inputFromView: InputFromView {
+        InputFromView(
+            name: nameField.textPublisher.orEmpty,
+            email: emailField.textPublisher.orEmpty,
+            submitTrigger: submitButton.tapPublisher
+        )
+    }
+
+    public func populate(with output: ViewModel.Output) -> [AnyCancellable] {
+        output.isSubmitEnabled --> submitButton.isEnabledBinder
+        output.loadingText --> submitButton.titleBinder(for: .normal)
+        output.isLoading --> spinner.isAnimatingBinder
+    }
+}
+
+// MARK: ViewModel.InputFromView
+public extension SignUpViewModel {
+	struct InputFromView {
+		public let name: AnyPublisher<String, Never>
+		public let email: AnyPublisher<String, Never>
+		public let submitTrigger: AnyPublisher<Void, Never>
+	}
+}
+
+// MARK: ViewModel.Output
+public extension SignUpViewModel {
+	struct Output {
+		public let isSubmitEnabled: AnyPublisher<Bool, Never>
+		public let isLoading: AnyPublisher<Bool, Never>
+	}
+}
+public extension SignUpViewModel.Output {
+	var loadingText: AnyPublisher<String, Never> {
+		isLoading.map { $0 ? "" : "Sign Up" }.eraseToAnyPublisher()
+	}
+}
+
+// MARK: NavigationStep
+public enum SignUpUserAction: Sendable {
+    case signedUp(SignedUpUser)
+}
+
+
+// MARK: ViewModel.InputFromView
+public final class SignUpViewModel: BaseViewModel<
+    SignUpUserAction, // NavigationStep
+    SignUpViewModel.InputFromView,
+    SignUpViewModel.Output
+> {
+	private let service: SignUpServicing
+	/* BaseViewModel declared `public let navigator = Navigator<NavigationStep>()` */
+	/* BaseViewModel declared `public var cancellables = Set<AnyCancellable>()` */
+
+	// MARK: BaseViewModel Overrides
+    override public func transform(input: Input) -> Output {
+        let activity = ActivityIndicator()
+
+        // Name + email both non-empty → form is valid.
+        let isFormValid: AnyPublisher<Bool, Never> = input.fromView.name
+            .combineLatest(input.fromView.email)
+            .map { name, email in
+                !name.trimmingCharacters(in: .whitespaces).isEmpty
+                    && !email.trimmingCharacters(in: .whitespaces).isEmpty
+            }
+            .eraseToAnyPublisher()
+
+        let isLoading = activity.asPublisher()
+
+        // Submit is enabled only when the form is valid AND we're not already
+        // mid-request (prevents double-taps from firing two sign-ups).
+        let isSubmitEnabled = isFormValid
+            .combineLatest(isLoading)
+            .map { valid, loading in valid && !loading }
+            .eraseToAnyPublisher()
+
+        // On submit-tap: snapshot the latest (name, email), call the service
+        // (tracking activity), forward the resulting user as `.signedUp`.
+        input.fromView.submitTrigger
+            .withLatestFrom(input.fromView.name.combineLatest(input.fromView.email))
+            .map { [service] name, email in
+                service.signUp(name: name, email: email)
+                    .trackActivity(activity)
+            }
+            .switchToLatest()
+            .sink { [weak self] user in
+                self?.navigator.next(.signedUp(user))
+            }
+            .store(in: &cancellables)
+
+        return Output(
+            isSubmitEnabled: isSubmitEnabled,
+            isLoading: isLoading
+        )
+    }
+}
+```
+
 # Library products
 The package ships six independent SPM library targets so consumers can pick exactly what they need:
 
@@ -52,4 +166,4 @@ open Examples/SignUpDemo/SignUpDemo.xcodeproj   # then ⌘R in Xcode
 The example shows the canonical wiring: scene = `SceneController<View>`, view-model subclasses the package's `BaseViewModel<NavigationStep, InputFromView, Output>` (which fixes `FromController` to `InputFromController` and provides a `Navigator<Step>`), coordinator subscribes to that navigator and routes the user-actions to push / pop / present transitions. 
 
 # History
-Implementation happened in 2018 in https://github.com/sajjon/zhip (originally https://github.com/openzesame/zhip); then called "SLC: SingleLineController". You can read my blog posts from 2018, [part one](https://medium.com/@sajjon/single-line-controller-fbe474857787) and [part two](https://medium.com/@sajjon/single-line-controller-advanced-case-406e76731ee6) - since ported from RxSwift to Combine and extracted into this separate repo.
+Implementation happened in 2018 in https://github.com/sajjon/zhip (originally https://github.com/openzesame/zhip); then called "SLC: SingleLineController". You can read my blog posts from 2018, [part one](https://medium.com/@sajjon/single-line-controller-fbe474857787) and [part two](https://medium.com/@sajjon/single-line-controller-advanced-case-406e76731ee6) - since ported from RxSwift to Combine and extracted into this separate repo.

Tests/NanoViewControllerCombineTests/UIControlPublisherDeadControlTests.swift

@@ -11,10 +11,10 @@ import XCTest
 /// dangling source.
 @MainActor
 final class UIControlPublisherDeadControlTests: XCTestCase {
-    func test_subscribingAfterControlDeallocated_completesImmediately() {
+    func test_subscribingAfterControlDeallocated_completesImmediately() throws {
         // ARRANGE
         var control: UIButton? = UIButton(type: .system)
-        let publisher = control!.publisher(for: .touchUpInside)
+        let publisher = try XCTUnwrap(control?.publisher(for: .touchUpInside))
 
         // ACT
         // Drop the only strong reference. The publisher holds a `WeakBox`,

Tests/NanoViewControllerCombineTests/UITextFieldPublishersTests.swift

@@ -177,7 +177,7 @@ final class UITextFieldPublishersTests: XCTestCase {
         // Force a contentSize that exceeds the frame so the publisher exercises
         // the `return contentOffset.y >= yThreshold * excess` branch (line 172).
         let view = UITextView(frame: CGRect(x: 0, y: 0, width: 100, height: 50))
-        view.contentSize = CGSize(width: 100, height: 1_000)
+        view.contentSize = CGSize(width: 100, height: 1000)
         view.contentOffset = CGPoint(x: 0, y: 990)
         var received: [Bool] = []