Merge pull request #114 from wwt/fix-the-things

Fixes some issues with preserving state while view swapping

Author: morganzellers

Sources/SwiftCurrent_SwiftUI/Views/WorkflowItem.swift

@@ -39,6 +39,7 @@ public struct WorkflowItem<F: FlowRepresentable & View, Wrapped: View, Content:
     @State private var modifierClosure: ((AnyFlowRepresentableView) -> Void)?
     @State private var flowPersistenceClosure: (AnyWorkflow.PassedArgs) -> FlowPersistence = { _ in .default }
     @State private var launchStyle: LaunchStyle.SwiftUI.PresentationType = .default
+    @State private var persistence: FlowPersistence = .default
 
     @EnvironmentObject private var model: WorkflowViewModel
     @EnvironmentObject private var launcher: Launcher
@@ -47,21 +48,21 @@ public struct WorkflowItem<F: FlowRepresentable & View, Wrapped: View, Content:
 
     public var body: some View {
         ViewBuilder {
-            if model.isLaunched == true {
-                if model.body?.extractErasedView() is Content {
-                    content
-                } else {
-                    wrapped
-                }
+            if let body = model.body?.extractErasedView() as? Content {
+                content ?? body
+            } else {
+                wrapped
             }
         }
         .onReceive(model.$body) {
             if let body = $0?.extractErasedView() as? Content {
                 content = body
+                persistence = $0?.value.metadata.persistence ?? .default
+            } else if persistence == .removedAfterProceeding {
+                content = nil
             }
         }
         .onReceive(inspection.notice) { inspection.visit(self, $0) }
-        .onChange(of: model.isLaunched) { if $0 == false { resetWorkflow() } }
     }
 
     private init<A, W, C, A1, W1, C1>(previous: WorkflowItem<A, W, C>, _ closure: () -> Wrapped) where Wrapped == WorkflowItem<A1, W1, C1> {
@@ -146,10 +147,6 @@ public struct WorkflowItem<F: FlowRepresentable & View, Wrapped: View, Content:
                                     flowPersistenceClosure: flowPersistenceClosure)
     }
 
-    private func resetWorkflow() {
-        launcher.workflow.launch(withOrchestrationResponder: model, passedArgs: launcher.launchArgs)
-    }
-
     private func ViewBuilder<V: View>(@ViewBuilder builder: () -> V) -> some View { builder() }
 
     private func factory(args: AnyWorkflow.PassedArgs) -> AnyFlowRepresentable {

Sources/SwiftCurrent_SwiftUI/Views/WorkflowLauncher.swift

@@ -47,10 +47,20 @@ public struct WorkflowLauncher<Content: View>: View {
     @StateObject private var launcher: Launcher
     @State private var onFinish = [(AnyWorkflow.PassedArgs) -> Void]()
     @State private var onAbandon = [() -> Void]()
+    @Binding private var isLaunched: Bool
 
     let inspection = Inspection<Self>()
 
     public var body: some View {
+        ViewBuilder {
+            if isLaunched {
+                workflowContent
+            }
+        }
+        .onChange(of: isLaunched) { if $0 == false { resetWorkflow() } }
+    }
+
+    private var workflowContent: some View {
         content
             .environmentObject(model)
             .environmentObject(launcher)
@@ -112,11 +122,13 @@ public struct WorkflowLauncher<Content: View>: View {
         _model = current._model
         _launcher = current._launcher
         _content = current._content
+        _isLaunched = current._isLaunched
         _onFinish = State(initialValue: onFinish)
         _onAbandon = State(initialValue: onAbandon)
     }
 
     private init<F, W, C>(isLaunched: Binding<Bool>, startingArgs: AnyWorkflow.PassedArgs, content: Content) where Content == WorkflowItem<F, W, C> {
+        _isLaunched = isLaunched
         let wf = AnyWorkflow.empty
         content.modify(workflow: wf)
         let model = WorkflowViewModel(isLaunched: isLaunched, launchArgs: startingArgs)
@@ -127,6 +139,12 @@ public struct WorkflowLauncher<Content: View>: View {
         _content = State(wrappedValue: content)
     }
 
+    private func resetWorkflow() {
+        launcher.workflow.launch(withOrchestrationResponder: model, passedArgs: launcher.launchArgs)
+    }
+
+    private func ViewBuilder<V: View>(@ViewBuilder builder: () -> V) -> some View { builder() }
+
     private func _onFinish(_ args: AnyWorkflow.PassedArgs?) {
         guard let args = args else { return }
         onFinish.forEach { $0(args) }

Tests/SwiftCurrent_SwiftUITests/SwiftCurrent_SwiftUITests.swift

@@ -693,6 +693,43 @@ final class SwiftCurrent_SwiftUIConsumerTests: XCTestCase, View {
             XCTAssert($0.value is StateIdentifiable, "Property named: \(label) was note @State")
         }
     }
+
+    func testWorkflowCanHaveADelayedLaunch() throws {
+        struct FR1: View, FlowRepresentable, Inspectable {
+            weak var _workflowPointer: AnyFlowRepresentable?
+
+            var body: some View {
+                Button("Proceed") { proceedInWorkflow() }
+            }
+        }
+
+        struct Wrapper: View, Inspectable {
+            @State var showingWorkflow = false
+            let inspection = Inspection<Self>()
+            var body: some View {
+                VStack {
+                    Button("") { showingWorkflow = true }
+                    WorkflowLauncher(isLaunched: $showingWorkflow) {
+                        thenProceed(with: FR1.self)
+                    }
+                }
+                .onReceive(inspection.notice) { inspection.visit(self, $0) }
+            }
+        }
+
+        let exp = ViewHosting.loadView(Wrapper()).inspection.inspect { view in
+            let stack = try view.vStack()
+            let launcher = try stack.view(WorkflowLauncher<WorkflowItem<FR1, Never, FR1>>.self, 1)
+            XCTAssertThrowsError(try launcher.view(WorkflowItem<FR1, Never, FR1>.self))
+            XCTAssertNoThrow(try stack.button(0).tap())
+            let fr1 = try launcher.view(WorkflowItem<FR1, Never, FR1>.self)
+            try fr1.actualView().inspect { fr1 in
+                XCTAssertNoThrow(try fr1.find(FR1.self))
+            }
+        }
+
+        wait(for: [exp], timeout: TestConstant.timeout)
+    }
 }
 
 @available(iOS 14.0, macOS 11, tvOS 14.0, watchOS 7.0, *)