Add onPresentation handler to present methods

Examples/CaseStudies/UIKit/ConciseEnumNavigationViewController.swift

@@ -44,6 +44,8 @@ class ConciseEnumNavigationViewController: UIViewController, UIKitCaseStudy {
       primaryAction: UIAction { [weak self] _ in
         self?.model.destination = .drillDown(.random(in: 1...1_000))
       })
+    let presentedLabel = UILabel(frame: .zero)
+    presentedLabel.textAlignment = .center
     let dismissLabel = UILabel(frame: .zero)
     dismissLabel.textAlignment = .center
 
@@ -52,6 +54,7 @@ class ConciseEnumNavigationViewController: UIViewController, UIKitCaseStudy {
       showSheetButton,
       drillDownButton,
       showSheetFromBooleanButton,
+      presentedLabel,
       dismissLabel,
     ])
     stack.axis = .vertical
@@ -89,7 +92,12 @@ class ConciseEnumNavigationViewController: UIViewController, UIKitCaseStudy {
     present(
       item: $model.destination.alert,
       id: \.self,
+      onPresentation: {
+        presentedLabel.text = "Alert presented"
+        dismissLabel.text = ""
+      },
       onDismiss: {
+        presentedLabel.text = ""
         dismissLabel.text = "Alert dismissed"
       }
     ) { message in
@@ -104,7 +112,12 @@ class ConciseEnumNavigationViewController: UIViewController, UIKitCaseStudy {
     present(
       item: $model.destination.sheet,
       id: \.self,
+      onPresentation: {
+        presentedLabel.text = "Sheet presented"
+        dismissLabel.text = ""
+      },
       onDismiss: {
+        presentedLabel.text = ""
         dismissLabel.text = "Sheet dismissed"
       }
     ) { count in
@@ -116,7 +129,12 @@ class ConciseEnumNavigationViewController: UIViewController, UIKitCaseStudy {
     }
     present(
       isPresented: UIBinding($model.destination.sheetWithoutPayload),
+      onPresentation: {
+        presentedLabel.text = "Sheet from boolean presented"
+        dismissLabel.text = ""
+      },
       onDismiss: {
+        presentedLabel.text = ""
         dismissLabel.text = "Sheet from boolean dismissed"
       }
     ) {

Examples/CaseStudiesTests/PresentationTests.swift

@@ -540,6 +540,47 @@ final class PresentationTests: XCTestCase {
     var destination: Destination?
   }
 
+  @MainActor func testOnPresentationNotCalledForUnrelatedPresentation() async throws {
+    class A: ViewController {}
+    class B: ViewController {}
+    class VC: ViewController {
+      @UIBindable var model = Destinations()
+      var onPresentationA: (() -> Void)?
+      var onPresentationB: (() -> Void)?
+      override func viewDidLoad() {
+        super.viewDidLoad()
+        present(isPresented: UIBinding($model.destination.presentedA)) { [weak self] in
+          self?.onPresentationA?()
+        } onDismiss: {
+        } content: {
+          A()
+        }
+        present(isPresented: UIBinding($model.destination.presentedB)) { [weak self] in
+          self?.onPresentationB?()
+        } onDismiss: {
+        } content: {
+          B()
+        }
+      }
+    }
+    let vc = VC()
+    vc.onPresentationB = { XCTFail() }
+    try await setUp(controller: vc)
+
+    await assertEventuallyNil(vc.presentedViewController)
+
+    withUITransaction(\.uiKit.disablesAnimations, true) {
+      vc.model.destination = .presentedA
+    }
+    await assertEventually(vc.presentedViewController is A)
+
+    vc.onPresentationB = nil
+    withUITransaction(\.uiKit.disablesAnimations, true) {
+      vc.model.destination = .presentedB
+    }
+    await assertEventually(vc.presentedViewController is B)
+  }
+
   @MainActor func testOnDismissNotCalledForUnrelatedDismissal() async throws {
     class A: ViewController {}
     class B: ViewController {}
@@ -594,6 +635,52 @@ final class PresentationTests: XCTestCase {
     await assertEventuallyNil(vc.model.pushedChild)
   }
 
+  @MainActor
+  func testRepresentWhileDismissing_StillCallsOnDismissAndOnPresentation() async throws {
+    final class Counter { var count = 0 }
+    let dismissCounter = Counter()
+    let presentationCounter = Counter()
+
+    final class VC: ViewController {
+      @UIBinding var presentedChild: Model?
+      let presentationCount: Counter
+      let dismissCount: Counter
+      init(presentationCounter: Counter, dismissCounter: Counter) {
+        self.presentationCount = presentationCounter
+        self.dismissCount = dismissCounter
+        super.init(nibName: nil, bundle: nil)
+      }
+      required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") }
+      override func viewDidLoad() {
+        super.viewDidLoad()
+        present(item: $presentedChild) { [presentationCount] in
+          presentationCount.count += 1
+        } onDismiss: { [dismissCount] in
+          dismissCount.count += 1
+        } content: { _ in
+          ViewController()
+        }
+      }
+    }
+
+    let vc = VC(presentationCounter: presentationCounter, dismissCounter: dismissCounter)
+    try await setUp(controller: vc)
+
+    vc.presentedChild = Model()
+    await assertEventuallyNotNil(vc.presentedViewController)
+    try await Task.sleep(for: .seconds(0.5))
+
+    vc.presentedChild = Model()
+    try await Task.sleep(for: .seconds(0.05))
+    vc.presentedChild = Model()
+
+    try await Task.sleep(for: .seconds(1))
+    await assertEventuallyNotNil(vc.presentedViewController)
+
+    XCTAssertEqual(dismissCounter.count, 2)
+    XCTAssertEqual(presentationCounter.count, 2)
+  }
+
   @MainActor
   func testRepresentWhileDismissing_StillCallsOnDismiss() async throws {
     final class DismissCounter { var count = 0 }
@@ -633,6 +720,48 @@ final class PresentationTests: XCTestCase {
 
     XCTAssertEqual(counter.count, 2)
   }
+
+  @MainActor
+  func testPresentCallsMultiplePresentationClosuresInOrder() async throws {
+    enum Event: String { case content, onPresentation, onDismiss }
+    final class Events { var events: [Event] = [] }
+    let events = Events()
+
+    final class VC: ViewController {
+      @UIBinding var presentedChild: Model?
+      let events: Events
+      init(events: Events) {
+        self.events = events
+        super.init(nibName: nil, bundle: nil)
+      }
+      required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") }
+      override func viewDidLoad() {
+        super.viewDidLoad()
+        present(item: $presentedChild) { [events] in
+          events.events.append(.onPresentation)
+        } onDismiss: { [events] in
+          events.events.append(.onDismiss)
+        } content: { [events] _ in
+          events.events.append(.content)
+          return ViewController()
+        }
+      }
+    }
+
+    let vc = VC(events: events)
+    try await setUp(controller: vc)
+
+    vc.presentedChild = Model()
+    await assertEventuallyNotNil(vc.presentedViewController)
+    try await Task.sleep(for: .seconds(0.75))
+
+    vc.presentedChild = Model()
+    try await Task.sleep(for: .seconds(0.75))
+    await assertEventuallyNotNil(vc.presentedViewController)
+
+    XCTAssertEqual(
+      events.events, [.content, .onPresentation, .content, .onDismiss, .onPresentation])
+  }
 }
 
 @Observable

Sources/UIKitNavigation/Navigation/Presentation.swift

@@ -11,6 +11,8 @@
     /// - Parameters:
     ///   - isPresented: A binding to a Boolean value that determines whether to present the view
     ///     controller.
+    ///   - onPresentation: The closure to execute when presentation completes. Equivalent to
+    ///     UIKit's standard presentation `completion` handler.
     ///   - onDismiss: The closure to execute when dismissing the view controller.
     ///   - content: A closure that returns the view controller to display over the current view
     ///     controller's content.
@@ -20,10 +22,13 @@
     @discardableResult
     public func present(
       isPresented: UIBinding<Bool>,
+      onPresentation: (() -> Void)? = nil,
       onDismiss: (() -> Void)? = nil,
       content: @escaping () -> UIViewController
     ) -> ObserveToken {
-      present(item: isPresented.toOptionalUnit, onDismiss: onDismiss) { _ in content() }
+      present(
+        item: isPresented.toOptionalUnit, onPresentation: onPresentation, onDismiss: onDismiss
+      ) { _ in content() }
     }
 
     /// Presents a view controller modally using the given item as a data source for its content.
@@ -36,6 +41,8 @@
     ///     content in a view controller that you create that is displayed to the user. If `item`'s
     ///     identity changes, the view controller is dismissed and replaced with a new one using the
     ///     same process.
+    ///   - onPresentation: The closure to execute when presentation completes. Equivalent to
+    ///     UIKit's standard presentation `completion` handler.
     ///   - onDismiss: The closure to execute when dismissing the view controller.
     ///   - content: A closure that returns the view controller to display over the current view
     ///     controller's content.
@@ -45,10 +52,13 @@
     @discardableResult
     public func present<Item: Identifiable>(
       item: UIBinding<Item?>,
+      onPresentation: (() -> Void)? = nil,
       onDismiss: (() -> Void)? = nil,
       content: @escaping (Item) -> UIViewController
     ) -> ObserveToken {
-      present(item: item, id: \.id, onDismiss: onDismiss, content: content)
+      present(
+        item: item, id: \.id, onPresentation: onPresentation, onDismiss: onDismiss, content: content
+      )
     }
 
     /// Presents a view controller modally using the given item as a data source for its content.
@@ -61,6 +71,8 @@
     ///     content in a view controller that you create that is displayed to the user. If `item`'s
     ///     identity changes, the view controller is dismissed and replaced with a new one using the
     ///     same process.
+    ///   - onPresentation: The closure to execute when presentation completes. Equivalent to
+    ///     UIKit's standard presentation `completion` handler.
     ///   - onDismiss: The closure to execute when dismissing the view controller.
     ///   - content: A closure that returns the view controller to display over the current view
     ///     controller's content.
@@ -71,10 +83,13 @@
     @discardableResult
     public func present<Item: Identifiable>(
       item: UIBinding<Item?>,
+      onPresentation: (() -> Void)? = nil,
       onDismiss: (() -> Void)? = nil,
       content: @escaping (UIBinding<Item>) -> UIViewController
     ) -> ObserveToken {
-      present(item: item, id: \.id, onDismiss: onDismiss, content: content)
+      present(
+        item: item, id: \.id, onPresentation: onPresentation, onDismiss: onDismiss, content: content
+      )
     }
 
     /// Presents a view controller modally using the given item as a data source for its content.
@@ -88,6 +103,8 @@
     ///     identity changes, the view controller is dismissed and replaced with a new one using the
     ///     same process.
     ///   - id: The key path to the provided item's identifier.
+    ///   - onPresentation: The closure to execute when presentation completes. Equivalent to
+    ///     UIKit's standard presentation `completion` handler.
     ///   - onDismiss: The closure to execute when dismissing the view controller.
     ///   - content: A closure that returns the view controller to display over the current view
     ///     controller's content.
@@ -98,10 +115,11 @@
     public func present<Item, ID: Hashable>(
       item: UIBinding<Item?>,
       id: KeyPath<Item, ID>,
+      onPresentation: (() -> Void)? = nil,
       onDismiss: (() -> Void)? = nil,
       content: @escaping (Item) -> UIViewController
     ) -> ObserveToken {
-      present(item: item, id: id, onDismiss: onDismiss) {
+      present(item: item, id: id, onPresentation: onPresentation, onDismiss: onDismiss) {
         content($0.wrappedValue)
       }
     }
@@ -117,6 +135,8 @@
     ///     identity changes, the view controller is dismissed and replaced with a new one using the
     ///     same process.
     ///   - id: The key path to the provided item's identifier.
+    ///   - onPresentation: The closure to execute when presentation completes. Equivalent to
+    ///     UIKit's standard presentation `completion` handler.
     ///   - onDismiss: The closure to execute when dismissing the view controller.
     ///   - content: A closure that returns the view controller to display over the current view
     ///     controller's content.
@@ -128,6 +148,7 @@
     public func present<Item, ID: Hashable>(
       item: UIBinding<Item?>,
       id: KeyPath<Item, ID>,
+      onPresentation: (() -> Void)? = nil,
       onDismiss: (() -> Void)? = nil,
       content: @escaping (UIBinding<Item>) -> UIViewController
     ) -> ObserveToken {
@@ -145,18 +166,30 @@
             presentedViewController._UIKitNavigation_onDismiss = {
               oldViewControllerOnDismiss?()
               if isRepresenting { onDismiss?() }
-              self.present(child, animated: !transaction.uiKit.disablesAnimations)
+              self.present(
+                child,
+                animated: !transaction.uiKit.disablesAnimations,
+                completion: onPresentation
+              )
             }
           } else {
             self.dismiss(
               animated: !transaction.uiKit.disablesAnimations
             ) {
               if isRepresenting { onDismiss?() }
-              self.present(child, animated: !transaction.uiKit.disablesAnimations)
+              self.present(
+                child,
+                animated: !transaction.uiKit.disablesAnimations,
+                completion: onPresentation
+              )
             }
           }
         } else {
-          self.present(child, animated: !transaction.uiKit.disablesAnimations)
+          self.present(
+            child,
+            animated: !transaction.uiKit.disablesAnimations,
+            completion: onPresentation
+          )
         }
       } dismiss: { child, transaction in
         child.dismiss(animated: !transaction.uiKit.disablesAnimations) {