Merge pull request #91 from wwt/state-craziness

Fixes issue with changing parent view state and vanishing Workflow Views
wwt · Aug 3, 2021 · 562cd51 · 562cd51
2 parents 82cf622 + 60ceddd
commit 562cd51
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Showing 2 changed files with 65 additions and 20 deletions.
diff --git a/Sources/SwiftCurrent_SwiftUI/Views/ModifiedWorkflowView.swift b/Sources/SwiftCurrent_SwiftUI/Views/ModifiedWorkflowView.swift
@@ -21,11 +21,12 @@ public struct ModifiedWorkflowView<Args, Wrapped: View, Content: View>: View {
     @Binding private var isLaunched: Bool
 
     let inspection = Inspection<Self>()
-    private let wrapped: Wrapped?
-    private let workflow: AnyWorkflow
-    private let launchArgs: AnyWorkflow.PassedArgs
-    private var onFinish = [(AnyWorkflow.PassedArgs) -> Void]()
-    private var onAbandon = [() -> Void]()
+    // These need to be state variables to survive SwiftUI re-rendering. Change under penalty of torture BY the codebase you modified.
+    @State private var wrapped: Wrapped?
+    @State private var workflow: AnyWorkflow
+    @State private var launchArgs: AnyWorkflow.PassedArgs
+    @State private var onFinish = [(AnyWorkflow.PassedArgs) -> Void]()
+    @State private var onAbandon = [() -> Void]()
 
     @StateObject private var model: WorkflowViewModel
     @StateObject private var launcher: Launcher
@@ -47,13 +48,13 @@ public struct ModifiedWorkflowView<Args, Wrapped: View, Content: View>: View {
     }
 
     init<A, FR>(_ workflowLauncher: WorkflowLauncher<A>, isLaunched: Binding<Bool>, item: WorkflowItem<FR, Content>) where Wrapped == Never, Args == FR.WorkflowOutput {
-        wrapped = nil
+        _wrapped = State(initialValue: nil)
         let wf = AnyWorkflow(Workflow<FR>(item.metadata))
-        workflow = wf
-        launchArgs = workflowLauncher.passedArgs
+        _workflow = State(initialValue: wf)
+        _launchArgs = State(initialValue: workflowLauncher.passedArgs)
         _isLaunched = isLaunched
-        onFinish = workflowLauncher.onFinish
-        onAbandon = workflowLauncher.onAbandon
+        _onFinish = State(initialValue: workflowLauncher.onFinish)
+        _onAbandon = State(initialValue: workflowLauncher.onAbandon)
         let model = WorkflowViewModel(isLaunched: isLaunched, launchArgs: workflowLauncher.passedArgs)
         _model = StateObject(wrappedValue: model)
         _launcher = StateObject(wrappedValue: Launcher(workflow: wf,
@@ -63,22 +64,22 @@ public struct ModifiedWorkflowView<Args, Wrapped: View, Content: View>: View {
 
     private init<A, W, C, FR>(_ workflowLauncher: ModifiedWorkflowView<A, W, C>, item: WorkflowItem<FR, Content>) where Wrapped == ModifiedWorkflowView<A, W, C>, Args == FR.WorkflowOutput {
         _model = workflowLauncher._model
-        wrapped = workflowLauncher
-        workflow = workflowLauncher.workflow
-        workflow.append(item.metadata)
-        launchArgs = workflowLauncher.launchArgs
+        _wrapped = State(initialValue: workflowLauncher)
+        _workflow = workflowLauncher._workflow
+        _launchArgs = workflowLauncher._launchArgs
         _isLaunched = workflowLauncher._isLaunched
         _launcher = workflowLauncher._launcher
-        onAbandon = workflowLauncher.onAbandon
+        _onAbandon = workflowLauncher._onAbandon
+        workflow.append(item.metadata)
     }
 
     private init(workflowLauncher: Self, onFinish: [(AnyWorkflow.PassedArgs) -> Void], onAbandon: [() -> Void]) {
         _model = workflowLauncher._model
-        wrapped = workflowLauncher.wrapped
-        workflow = workflowLauncher.workflow
-        self.onFinish = onFinish
-        self.onAbandon = onAbandon
-        launchArgs = workflowLauncher.launchArgs
+        _wrapped = workflowLauncher._wrapped
+        _workflow = workflowLauncher._workflow
+        _onFinish = State(initialValue: onFinish)
+        _onAbandon = State(initialValue: onAbandon)
+        _launchArgs = workflowLauncher._launchArgs
         _isLaunched = workflowLauncher._isLaunched
         _launcher = workflowLauncher._launcher
     }

diff --git a/Tests/SwiftCurrent_SwiftUITests/SwiftCurrent_SwiftUITests.swift b/Tests/SwiftCurrent_SwiftUITests/SwiftCurrent_SwiftUITests.swift
@@ -627,4 +627,48 @@ final class SwiftCurrent_SwiftUIConsumerTests: XCTestCase {
 
         wait(for: [expectOnFinish, expectViewLoaded], timeout: TestConstant.timeout)
     }
+
+    func testWorkflowCorrectlyHandlesState() throws {
+        final class Launcher: ObservableObject {
+            var onFinishCalled = false
+            init(workflow: AnyWorkflow,
+                 responder: OrchestrationResponder,
+                 launchArgs: AnyWorkflow.PassedArgs) {
+                if workflow.orchestrationResponder == nil {
+                    workflow.launch(withOrchestrationResponder: responder, passedArgs: launchArgs)
+                }
+            }
+        }
+        struct ModifiedWorkflowViewExplorer<A, W, C>: View, Inspectable {
+            @Binding var isLaunched: Bool
+
+            let inspection = Inspection<Self>()
+            @State var wrapped: W?
+            @State var workflow: AnyWorkflow
+            @State var launchArgs: AnyWorkflow.PassedArgs
+            @State var onFinish = [(AnyWorkflow.PassedArgs) -> Void]()
+            @State var onAbandon = [() -> Void]()
+
+            @StateObject private var model: WorkflowViewModel
+            @StateObject private var launcher: Launcher
+
+            var body: some View { EmptyView() }
+        }
+
+        struct FR1: View, FlowRepresentable {
+            weak var _workflowPointer: AnyFlowRepresentable?
+
+            var body: some View {
+                Button("Proceed") { proceedInWorkflow() }
+            }
+        }
+
+        let workflowView = WorkflowLauncher(isLaunched: .constant(true))
+            .thenProceed(with: WorkflowItem(FR1.self))
+
+        let explorer = unsafeBitCast(workflowView, to: ModifiedWorkflowViewExplorer<Never, Never, FR1>.self)
+
+        // if the unsafeBitCast worked, then everything is a state var.
+        XCTAssertNil(explorer.wrapped)
+    }
 }