Fixed nested UIHostingController being added as its own child on iOS 26

Levitan.xcodeproj/project.pbxproj

@@ -13,6 +13,7 @@
 		AB0000062F2139F6006016DE /* EnvironmentValues+ComponentMountingPolicy.swift in Sources */ = {isa = PBXBuildFile; fileRef = AB0000052F2139F6006016DE /* EnvironmentValues+ComponentMountingPolicy.swift */; };
 		AB0000072F2139F6006016DE /* EnvironmentValues+ComponentMountingPolicy.swift in Sources */ = {isa = PBXBuildFile; fileRef = AB0000052F2139F6006016DE /* EnvironmentValues+ComponentMountingPolicy.swift */; };
 		AB0000082F2139F6006016DE /* EnvironmentValues+ComponentMountingPolicy.swift in Sources */ = {isa = PBXBuildFile; fileRef = AB0000052F2139F6006016DE /* EnvironmentValues+ComponentMountingPolicy.swift */; };
+		BD630107286740451D607380 /* ComponentHostingNestingTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = B1A3BA78569B30A7793E48E7 /* ComponentHostingNestingTests.swift */; };
 		C005088D2F2139F6006016DE /* ComponentFrame.swift in Sources */ = {isa = PBXBuildFile; fileRef = C00508762F2139F6006016DE /* ComponentFrame.swift */; };
 		C005088E2F2139F6006016DE /* ComponentModifier.swift in Sources */ = {isa = PBXBuildFile; fileRef = C00508862F2139F6006016DE /* ComponentModifier.swift */; };
 		C005088F2F2139F6006016DE /* AnyComponent.swift in Sources */ = {isa = PBXBuildFile; fileRef = C005084C2F2139F6006016DE /* AnyComponent.swift */; };
@@ -1141,6 +1142,7 @@
 /* Begin PBXFileReference section */
 		AB0000012F2139F6006016DE /* ComponentMountingPolicy.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComponentMountingPolicy.swift; sourceTree = "<group>"; };
 		AB0000052F2139F6006016DE /* EnvironmentValues+ComponentMountingPolicy.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "EnvironmentValues+ComponentMountingPolicy.swift"; sourceTree = "<group>"; };
+		B1A3BA78569B30A7793E48E7 /* ComponentHostingNestingTests.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = ComponentHostingNestingTests.swift; sourceTree = "<group>"; };
 		C0007FFA23CBAAA5005F95E0 /* .swift-version */ = {isa = PBXFileReference; lastKnownFileType = text; path = ".swift-version"; sourceTree = "<group>"; };
 		C005084C2F2139F6006016DE /* AnyComponent.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AnyComponent.swift; sourceTree = "<group>"; };
 		C005084D2F2139F6006016DE /* AnyComponentPresenter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AnyComponentPresenter.swift; sourceTree = "<group>"; };
@@ -2910,6 +2912,7 @@
 				C0C3C5932DD5E5A70058A201 /* TestPlans */,
 				C0A01A1523CB8FFC00AC2C3A /* .swiftlint.yml */,
 				C057F01E23CB8EEB00C2D895 /* Info.plist */,
+				B1A3BA78569B30A7793E48E7 /* ComponentHostingNestingTests.swift */,
 			);
 			path = Tests;
 			sourceTree = "<group>";
@@ -3545,6 +3548,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				BD630107286740451D607380 /* ComponentHostingNestingTests.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

Sources/Component/Hosting/ComponentHostingRoot.swift

@@ -7,7 +7,10 @@ internal struct ComponentHostingRoot<Content: View>: View {
     internal var context: ComponentContext
 
     internal var body: some View {
+        // Не через context.componentViewController: до iOS 27 это чтение протекает в окружение
+        // внешнего хостинга, см. ComponentHostingNestingTests.
         let theme = context
+            .resolveEnvironment(EnvironmentValues())
             .componentViewController?
             .view
             .tokens

Tests/ComponentHostingNestingTests.swift

@@ -0,0 +1,116 @@
+#if canImport(UIKit)
+import SwiftUI
+import UIKit
+import XCTest
+@testable import Levitan
+
+private struct NestedText: Component {
+
+    let text: String
+
+    var body: some View {
+        Text(text)
+    }
+}
+
+private struct NestingCard: FallbackComponent {
+
+    typealias UIView = NestingCardView
+
+    let text: String
+}
+
+@MainActor
+private enum NestingCardLeaks {
+
+    static var texts: [String] = []
+}
+
+/// UIKit-компонент со SwiftUI-содержимым, как карточка дизайн-системы.
+private final class NestingCardView: UIView {
+
+    private let contentView = ComponentHostingView<NestedText>()
+
+    override init(frame: CGRect) {
+        super.init(frame: frame)
+
+        contentView.frame = bounds
+        contentView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
+
+        addSubview(contentView)
+    }
+
+    @available(*, unavailable)
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+}
+
+private struct NestingRoot: View {
+
+    let revision: Int
+
+    var body: some View {
+        ScrollView {
+            LazyVStack {
+                ForEach(0..<3) { index in
+                    NestingCard(text: "\(index)-\(revision)")
+                }
+            }
+        }
+    }
+}
+
+@MainActor
+final class ComponentHostingNestingTests: XCTestCase {
+
+    func testNestedHostingControllerDoesNotLeakIntoParentComponentContext() {
+        let window = UIWindow(frame: CGRect(x: 0, y: 0, width: 402, height: 874))
+        let hostingController = UIHostingController(rootView: NestingRoot(revision: 0))
+
+        NestingCardLeaks.texts = []
+
+        window.rootViewController = hostingController
+        window.makeKeyAndVisible()
+
+        // Утечка проявляется только на повторных обновлениях уже встроенных компонентов
+        for revision in 0..<3 {
+            hostingController.rootView = NestingRoot(revision: revision)
+            hostingController.view.setNeedsLayout()
+            hostingController.view.layoutIfNeeded()
+
+            RunLoop.main.run(until: Date().addingTimeInterval(0.3))
+        }
+
+        XCTAssertEqual(NestingCardLeaks.texts, [])
+        XCTAssertFalse(hostingController.children.isEmpty)
+
+        window.isHidden = true
+    }
+}
+
+extension NestingCardView: FallbackComponentView {
+
+    static func sizing(
+        for content: NestingCard,
+        fitting size: CGSize,
+        context: ComponentContext
+    ) -> ComponentSizing {
+        ComponentSizing(width: .fill, height: .fixed(44.0))
+    }
+
+    func update(with content: NestingCard, context: ComponentContext) {
+        // Контекст карточки не должен содержать ее собственный UIHostingController:
+        // иначе ComponentHostingView добавит его дочерним самому себе, и UIKit упадет с переполнением стека.
+        // Обновление пропускается, чтобы утечка завершила тест проверкой, а не падением.
+        if context.componentViewController is ComponentHostingController<ComponentHostingRoot<NestedText>> {
+            return NestingCardLeaks.texts.append(content.text)
+        }
+
+        contentView.update(
+            with: NestedText(text: content.text),
+            context: context
+        )
+    }
+}
+#endif