Fixes removedAfterProceeding not dismissing final view when applied to final item in Workflow.

Sources/Workflow/LinkedList/LinkedList.swift

@@ -66,4 +66,36 @@ public class LinkedList<Value>: Sequence, CustomStringConvertible {
     func toArray() -> [Element.Value] {
         map { $0.value }
     }
+
+    /**
+     Returns the last element of the sequence that satisfies the given
+     predicate.
+
+     - Parameter predicate: A closure that takes an element of the sequence as
+     its argument and returns a Boolean value indicating whether the
+     element is a match.
+     - Returns: The last element of the sequence that satisfies `predicate`,
+     or `nil` if there is no element that satisfies `predicate`.
+     - Complexity: O(n). The linked list must traverse to the end.
+
+     #### Example
+     This example uses the `last(where:)` method to find the last
+     negative number in an array of integers:
+     */
+    /// ```swift
+    ///  let numbers = LinkedList([3, 7, 4, -2, 9, -6, 10, 1])
+    ///  if let lastNegative = numbers.last(where: { $0.value < 0 }) {
+    ///      print("The last negative number is \(lastNegative).")
+    ///  }
+    ///  // Prints "The last negative number is -6."
+    /// ```
+    public func last(where predicate: (Element) throws -> Bool) rethrows -> Element? {
+        var lastElement: Element?
+
+        for element in self where try predicate(element) {
+                lastElement = element
+        }
+
+        return lastElement
+    }
 }

Sources/Workflow/Models/Workflow.swift

@@ -123,7 +123,7 @@ public final class Workflow<F: FlowRepresentable>: LinkedList<_WorkflowItem> {
         }
 
         guard let first = firstLoadedInstance  else {
-            onFinish?(passedArgs)
+            orchestrationResponder.complete(AnyWorkflow(self), passedArgs: passedArgs, onFinish: onFinish)
             return nil
         }
 
@@ -191,7 +191,7 @@ public final class Workflow<F: FlowRepresentable>: LinkedList<_WorkflowItem> {
         }
 
         guard let nextNode = nextLoadedNode else {
-            onFinish?(argsToPass)
+            orchestrationResponder?.complete(AnyWorkflow(self), passedArgs: argsToPass, onFinish: onFinish)
             return
         }
 

Sources/Workflow/Protocols/OrchestrationResponder.swift

@@ -32,6 +32,13 @@ public protocol OrchestrationResponder {
      - Parameter onFinish: A closure that is executed when the responder is finished abandoning.
      */
     func abandon(_ workflow: AnyWorkflow, onFinish: (() -> Void)?)
+    /**
+     Respond to the `Workflow` completing.
+     - Parameter workflow: The `AnyWorkflow` that is being completed.
+     - Parameter passedArgs: The `AnyWorkflow.PassedArgs` to be passed to `onFinish`.
+     - Parameter onFinish: A closure that is executed when the responder is finished completing.
+     */
+    func complete(_ workflow: AnyWorkflow, passedArgs: AnyWorkflow.PassedArgs, onFinish: ((AnyWorkflow.PassedArgs) -> Void)?)
 }
 
 extension OrchestrationResponder {

Sources/Workflow/TypeErased/AnyWorkflow.swift

@@ -42,6 +42,10 @@ extension AnyWorkflow: Sequence {
     public func makeIterator() -> LinkedList<_WorkflowItem>.Iterator {
         storageBase.makeIterator()
     }
+
+    public func last(where predicate: (LinkedList<_WorkflowItem>.Element) throws -> Bool) rethrows -> LinkedList<_WorkflowItem>.Element? {
+        try storageBase.last(where: predicate)
+    }
 }
 
 extension AnyWorkflow {
@@ -69,15 +73,21 @@ extension AnyWorkflow {
 
 fileprivate class AnyWorkflowStorageBase {
     var orchestrationResponder: OrchestrationResponder?
-    var count: Int { fatalError("Count not overriden by AnyWorkflowStorage") }
+    var count: Int { fatalError("Count not overridden by AnyWorkflowStorage") }
+
+    // https://github.com/Tyler-Keith-Thompson/Workflow/blob/master/STYLEGUIDE.md#type-erasure
+    // swiftlint:disable:next unavailable_function
+    func _abandon() { fatalError("_abandon not overridden by AnyWorkflowStorage") }
 
     // https://github.com/Tyler-Keith-Thompson/Workflow/blob/master/STYLEGUIDE.md#type-erasure
     // swiftlint:disable:next unavailable_function
-    func _abandon() { fatalError("_abandon not overriden by AnyWorkflowStorage") }
+    func makeIterator() -> LinkedList<_WorkflowItem>.Iterator { fatalError("makeIterator not overridden by AnyWorkflowStorage") }
 
     // https://github.com/Tyler-Keith-Thompson/Workflow/blob/master/STYLEGUIDE.md#type-erasure
     // swiftlint:disable:next unavailable_function
-    func makeIterator() -> LinkedList<_WorkflowItem>.Iterator { fatalError("makeIterator not overriden by AnyWorkflowStorage") }
+    func last(where _: (LinkedList<_WorkflowItem>.Element) throws -> Bool) rethrows -> LinkedList<_WorkflowItem>.Element? {
+        fatalError("last(where:) not overridden by AnyWorkflowStorage")
+    }
 }
 
 fileprivate final class AnyWorkflowStorage<F: FlowRepresentable>: AnyWorkflowStorageBase {
@@ -105,4 +115,8 @@ fileprivate final class AnyWorkflowStorage<F: FlowRepresentable>: AnyWorkflowSto
     override func makeIterator() -> LinkedList<_WorkflowItem>.Iterator {
         workflow.makeIterator()
     }
+
+    override func last(where predicate: (LinkedList<_WorkflowItem>.Element) throws -> Bool) rethrows -> LinkedList<_WorkflowItem>.Element? {
+        try workflow.last(where: predicate)
+    }
 }

Sources/WorkflowUIKit/UIKitPresenter.swift

@@ -15,6 +15,7 @@ open class UIKitPresenter: OrchestrationResponder {
     let launchedFromVC: UIViewController
     let launchedPresentationType: LaunchStyle.PresentationType
     var firstLoadedInstance: UIViewController?
+    weak var internalNavigationController: UINavigationController?
 
     /**
      Creates a `UIKitPresenter` that can respond to a `Workflow`'s actions.
@@ -61,6 +62,17 @@ open class UIKitPresenter: OrchestrationResponder {
         abandon(workflow, animated: true, onFinish: onFinish)
     }
 
+    public func complete(_ workflow: AnyWorkflow, passedArgs: AnyWorkflow.PassedArgs, onFinish: ((AnyWorkflow.PassedArgs) -> Void)?) {
+        let lastInstance = workflow.last { $0.value.instance != nil }
+
+        if lastInstance?.value.metadata.persistence == .removedAfterProceeding,
+           let view = lastInstance?.value.instance?.underlyingInstance as? UIViewController {
+            destroy(view) { onFinish?(passedArgs) }
+        } else {
+            onFinish?(passedArgs)
+        }
+    }
+
     func abandon(_ workflow: AnyWorkflow, animated: Bool, onFinish: (() -> Void)?) {
         guard let first = firstLoadedInstance else { return }
         if let nav = first.navigationController {
@@ -89,12 +101,21 @@ open class UIKitPresenter: OrchestrationResponder {
         }
     }
 
-    private func destroy(_ view: UIViewController) {
+    private func destroy(_ view: UIViewController, completion: (() -> Void)? = nil) {
         if let nav = view.navigationController {
             let vcs = nav.viewControllers.filter {
                 $0 !== view
             }
-            nav.setViewControllers(vcs, animated: false)
+
+            if vcs.isEmpty && nav === internalNavigationController {
+                nav.presentingViewController?.dismiss(animated: false) { [weak self] in
+                    self?.internalNavigationController?.setViewControllers(vcs, animated: false)
+                    completion?()
+                }
+            } else {
+                nav.setViewControllers(vcs, animated: false)
+                completion?()
+            }
         } else {
             let parent = view.presentingViewController
             let child = view.presentedViewController
@@ -104,7 +125,11 @@ open class UIKitPresenter: OrchestrationResponder {
             parent?.dismiss(animated: false) {
                 if let p = parent,
                    let c = child {
-                    p.present(c, animated: false)
+                    p.present(c, animated: false) {
+                        completion?()
+                    }
+                } else {
+                    completion?()
                 }
             }
         }
@@ -153,6 +178,7 @@ open class UIKitPresenter: OrchestrationResponder {
                                               completion: (() -> Void)?) {
         if LaunchStyle.PresentationType(rawValue: to.value.metadata.launchStyle) == .navigationStack {
             let nav = UINavigationController(rootViewController: view)
+            internalNavigationController = nav
             if let modalPresentationStyle = UIModalPresentationStyle.styleFor(style) {
                 nav.modalPresentationStyle = modalPresentationStyle
             }
@@ -174,6 +200,7 @@ open class UIKitPresenter: OrchestrationResponder {
             completion?()
         } else {
             let nav = UINavigationController(rootViewController: view)
+            internalNavigationController = nav
             root.present(nav, animated: animated, completion: completion)
         }
     }

Tests/WorkflowExampleTests/Mocks/MockOrchestrationResponder.swift

@@ -10,6 +10,19 @@ import Foundation
 import Workflow
 
 class MockOrchestrationResponder: OrchestrationResponder {
+    var completeCalled = 0
+    var lastPassedArgs: AnyWorkflow.PassedArgs?
+    var lastCompleteOnFinish: ((AnyWorkflow.PassedArgs) -> Void)?
+    var complete_EnableDefaultImplementation = false
+    func complete(_ workflow: AnyWorkflow, passedArgs: AnyWorkflow.PassedArgs, onFinish: ((AnyWorkflow.PassedArgs) -> Void)?) {
+        lastWorkflow = workflow
+        lastPassedArgs = passedArgs
+        lastCompleteOnFinish = onFinish
+        completeCalled += 1
+
+        if complete_EnableDefaultImplementation { onFinish?(passedArgs) }
+    }
+
     var launchCalled = 0
     var lastTo: AnyWorkflow.Element?
     func launch(to: AnyWorkflow.Element) {

Tests/WorkflowTests/LinkedListTests.swift

@@ -409,6 +409,33 @@ class LinkedListTests: XCTestCase {
         XCTAssertEqual(list.last?.value, 4)
     }
 
+    func testLastWhere() {
+        class Obj {
+            let num: Int
+            init(_ num: Int) { self.num = num }
+        }
+        let list = LinkedList([Obj(1), Obj(4), Obj(4), Obj(3)])
+        let expectedValue = list.first?.traverse(2)?.value
+
+        let last = list.last { $0.value.num == 4 }
+
+        XCTAssertEqual(last?.value.num, 4)
+        XCTAssert(last?.value === expectedValue)
+
+        let notFound = list.last { $0.value.num == 10 }
+
+        XCTAssertNil(notFound)
+    }
+
+    func testLastWhereAllowsThrowingClosure() {
+        class Obj { func throwing() throws -> Bool { true } }
+        let list = LinkedList([Obj(), Obj(), Obj()])
+
+        let foundObj = try? list.last { try $0.value.throwing() }
+
+        XCTAssert(foundObj?.value === list.last?.value)
+    }
+
     func testEquatability() {
         let list = LinkedList([1, 2, 3])
         let list2 = LinkedList([1, 2, 3])

Tests/WorkflowTests/OrchestrationResponder/MockOrchestrationResponder.swift

@@ -26,7 +26,6 @@ class MockOrchestrationResponder: OrchestrationResponder {
         allFroms.last
     }
 
-    var lastCompletion:(() -> Void)?
     func proceed(to: AnyWorkflow.Element,
                  from: AnyWorkflow.Element) {
         allTos.append(to)
@@ -49,4 +48,17 @@ class MockOrchestrationResponder: OrchestrationResponder {
         lastOnFinish = onFinish
         abandonCalled += 1
     }
+
+    var completeCalled = 0
+    var lastPassedArgs: AnyWorkflow.PassedArgs?
+    var lastCompleteOnFinish: ((AnyWorkflow.PassedArgs) -> Void)?
+    var complete_EnableDefaultImplementation = false
+    func complete(_ workflow: AnyWorkflow, passedArgs: AnyWorkflow.PassedArgs, onFinish: ((AnyWorkflow.PassedArgs) -> Void)?) {
+        lastWorkflow = workflow
+        lastPassedArgs = passedArgs
+        lastCompleteOnFinish = onFinish
+        completeCalled += 1
+
+        if complete_EnableDefaultImplementation { onFinish?(passedArgs) }
+    }
 }

Tests/WorkflowTests/OrchestrationResponder/OrchestrationResponderTests.swift

@@ -53,6 +53,7 @@ class OrchestrationResponderTests: XCTestCase {
             .thenProceed(with: FR2.self)
             .thenProceed(with: FR3.self)
         let responder = MockOrchestrationResponder()
+        responder.complete_EnableDefaultImplementation = true
         let expectation = self.expectation(description: "OnFinish called")
 
         let launchedRepresentable = wf.launch(withOrchestrationResponder: responder) { _ in expectation.fulfill() }
@@ -62,6 +63,10 @@ class OrchestrationResponderTests: XCTestCase {
         (responder.lastTo?.value.instance?.underlyingInstance as? FR3)?.proceedInWorkflow()
 
         wait(for: [expectation], timeout: 3)
+
+        XCTAssertEqual(responder.completeCalled, 1)
+        XCTAssertNotNil(responder.lastPassedArgs)
+        XCTAssertNotNil(responder.lastCompleteOnFinish)
     }
 
     func testWorkflowCallsOnFinishWhenItIsDone_andPassesForwardLastArguments() {
@@ -74,6 +79,7 @@ class OrchestrationResponderTests: XCTestCase {
             .thenProceed(with: FR2.self)
             .thenProceed(with: FR3.self)
         let responder = MockOrchestrationResponder()
+        responder.complete_EnableDefaultImplementation = true
         let expectation = self.expectation(description: "OnFinish called")
 
         let launchedRepresentable = wf.launch(withOrchestrationResponder: responder) { args in
@@ -86,6 +92,10 @@ class OrchestrationResponderTests: XCTestCase {
         (responder.lastTo?.value.instance?.underlyingInstance as? FR3)?.proceedInWorkflow(val)
 
         wait(for: [expectation], timeout: 3)
+
+        XCTAssertEqual(responder.completeCalled, 1)
+        XCTAssertNotNil(responder.lastPassedArgs)
+        XCTAssertNotNil(responder.lastCompleteOnFinish)
     }
 
     func testWorkflowCanProceedForwardAndBackwardThroughFlow() {
@@ -137,6 +147,7 @@ class OrchestrationResponderTests: XCTestCase {
             .thenProceed(with: FR2.self)
             .thenProceed(with: FR3.self)
         let responder = MockOrchestrationResponder()
+        responder.complete_EnableDefaultImplementation = true
         let expectation = self.expectation(description: "OnFinish called")
 
         let launchedRepresentable = wf.launch(withOrchestrationResponder: responder) { _ in expectation.fulfill() }
@@ -149,6 +160,10 @@ class OrchestrationResponderTests: XCTestCase {
         (responder.lastTo?.value.instance?.underlyingInstance as? FR3)?.proceedInWorkflow()
 
         wait(for: [expectation], timeout: 3)
+
+        XCTAssertEqual(responder.completeCalled, 1)
+        XCTAssertNotNil(responder.lastPassedArgs)
+        XCTAssertNotNil(responder.lastCompleteOnFinish)
     }
 
     func testWorkflowCallsOnFinishWhenItIsDone_andPassesForwardInitialArguments_EvenWhenMovingBackwardsForABit() {
@@ -192,6 +207,7 @@ class OrchestrationResponderTests: XCTestCase {
             .thenProceed(with: FR2.self)
             .thenProceed(with: FR3.self)
         let responder = MockOrchestrationResponder()
+        responder.complete_EnableDefaultImplementation = true
         let expectation = self.expectation(description: "OnFinish called")
 
         let launchedRepresentable = wf.launch(withOrchestrationResponder: responder,
@@ -214,6 +230,10 @@ class OrchestrationResponderTests: XCTestCase {
         (responder.lastTo?.value.instance?.underlyingInstance as? FR3)?.proceedInWorkflow(val)
 
         wait(for: [expectation], timeout: 3)
+
+        XCTAssertEqual(responder.completeCalled, 1)
+        XCTAssertNotNil(responder.lastPassedArgs)
+        XCTAssertNotNil(responder.lastCompleteOnFinish)
     }
 }