Swift 6 compatibility (#108)

# Swift 6 compatibility

## ♻️ Current situation & Problem
This PR fixes the swift concurrency flag. There weren't any concurrency
warnings left when compiling with the latest Swift 6 toolchain that is
part of Xcode 16 beta 3. Note, that Xcode 15 will trigger some warnings
as some symbols aren't annotated as Sendable in the previous SDK.
Further, some sendability checks changed.

This PR changes some actor isolations of some types and interfaces. Most
importantly, we add `@MainActor` isolation to the `Module/configure()`
method. We found, that a lot of modules manipulate `@MainActor` isolated
properties in their configure method (those that are relevant for UI
components) but cannot do so without spawning a new Task, as the
configure method previously didn't have `@MainActor` guarantees. Except
for out-of-band module loading, `configure()` would have always been
called on the Main Actor (through SwiftUI initialization). Making all
module interactions to be isolated to `@MainActor` greatly simplifies
some of our internal state handling.

## ⚙️ Release Notes 
* Fix swift strict concurrency flag.
* Resolve some strict concurrency warnings.

### Breaking Changes
* `Module/configure()` is now isolated to `@MainActor`.
* `Spezi/loadModule(_:ownership:)` and `Spezi/unloadModule(_:)` are now
isolated to `@MainActor`.

## 📚 Documentation
Minor documentation files.


## ✅ Testing
Test target was updated to latest concurrency changes as well.


## 📝 Code of Conduct & Contributing Guidelines 

By submitting creating this pull request, you agree to follow our [Code
of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md):
- [x] I agree to follow the [Code of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md).

.github/workflows/build-and-test.yml

@@ -24,6 +24,16 @@ jobs:
       scheme: Spezi-Package
       resultBundle: Spezi-Package-iOS.xcresult
       artifactname: Spezi-Package-iOS.xcresult
+  buildandtest_ios_latest:
+    name: Build and Test Swift Package iOS Latest
+    uses: StanfordSpezi/.github/.github/workflows/xcodebuild-or-fastlane.yml@v2
+    with:
+      runsonlabels: '["macOS", "self-hosted"]'
+      scheme: Spezi-Package
+      xcodeversion: latest
+      swiftVersion: 6
+      resultBundle: Spezi-Package-iOS-Latest.xcresult
+      artifactname: Spezi-Package-iOS-Latest.xcresult
   buildandtest_watchos:
     name: Build and Test Swift Package watchOS
     uses: StanfordSpezi/.github/.github/workflows/xcodebuild-or-fastlane.yml@v2
@@ -69,6 +79,17 @@ jobs:
       scheme: TestApp
       resultBundle: TestApp-iOS.xcresult
       artifactname: TestApp-iOS.xcresult
+  buildandtestuitests_ios_latest:
+    name: Build and Test UI Tests iOS Latest
+    uses: StanfordSpezi/.github/.github/workflows/xcodebuild-or-fastlane.yml@v2
+    with:
+      runsonlabels: '["macOS", "self-hosted"]'
+      path: Tests/UITests
+      scheme: TestApp
+      xcodeversion: latest
+      swiftVersion: 6
+      resultBundle: TestApp-iOS-Latest.xcresult
+      artifactname: TestApp-iOS-Latest.xcresult
   buildandtestuitests_visionos:
     name: Build and Test UI Tests visionOS
     uses: StanfordSpezi/.github/.github/workflows/xcodebuild-or-fastlane.yml@v2

Package.swift

@@ -12,9 +12,9 @@ import class Foundation.ProcessInfo
 import PackageDescription
 
 #if swift(<6)
-let swiftConcurrency: SwiftSetting = .enableExperimentalFeature("SwiftConcurrency")
+let swiftConcurrency: SwiftSetting = .enableExperimentalFeature("StrictConcurrency")
 #else
-let swiftConcurrency: SwiftSetting = .enableUpcomingFeature("SwiftConcurrency")
+let swiftConcurrency: SwiftSetting = .enableUpcomingFeature("StrictConcurrency")
 #endif
 
 

Sources/Spezi/Capabilities/Communication/ProvidePropertyWrapper.swift

@@ -16,15 +16,15 @@ import XCTRuntimeAssertions
 protocol CollectionBasedProvideProperty {
     func collectArrayElements<Repository: SharedRepository<SpeziAnchor>>(into repository: inout Repository)
 
-    func clearValues()
+    func clearValues(isolated: Bool)
 }
 
 
 /// A protocol that identifies a  ``_ProvidePropertyWrapper`` which `Value` type is a `Optional`.
 protocol OptionalBasedProvideProperty {
     func collectOptional<Repository: SharedRepository<SpeziAnchor>>(into repository: inout Repository)
 
-    func clearValues()
+    func clearValues(isolated: Bool)
 }
 
 
@@ -69,7 +69,7 @@ public class _ProvidePropertyWrapper<Value> {
 
 
     deinit {
-        clear()
+        clear(isolated: false)
     }
 }
 
@@ -143,15 +143,32 @@ extension _ProvidePropertyWrapper: StorageValueProvider {
         collected = true
     }
 
+    @MainActor
     func clear() {
+        clear(isolated: true)
+    }
+
+    private func clear(isolated: Bool) {
         collected = false
 
         if let wrapperWithOptional = self as? OptionalBasedProvideProperty {
-            wrapperWithOptional.clearValues()
+            wrapperWithOptional.clearValues(isolated: isolated)
         } else if let wrapperWithArray = self as? CollectionBasedProvideProperty {
-            wrapperWithArray.clearValues()
+            wrapperWithArray.clearValues(isolated: isolated)
+        } else {
+            performClear(isolated: isolated, of: Value.self)
+        }
+    }
+
+    private func performClear<V>(isolated: Bool, of type: V.Type) {
+        if isolated {
+            MainActor.assumeIsolated { [spezi, id] in
+                spezi?.handleCollectedValueRemoval(for: id, of: type)
+            }
         } else {
-            spezi?.handleCollectedValueRemoval(for: id, of: Value.self)
+            Task { @MainActor [spezi, id] in
+                spezi?.handleCollectedValueRemoval(for: id, of: type)
+            }
         }
     }
 }
@@ -162,8 +179,8 @@ extension _ProvidePropertyWrapper: CollectionBasedProvideProperty where Value: A
         repository.setValues(for: id, storedValue.unwrappedArray)
     }
 
-    func clearValues() {
-        spezi?.handleCollectedValueRemoval(for: id, of: Value.Element.self)
+    func clearValues(isolated: Bool) {
+        performClear(isolated: isolated, of: Value.Element.self)
     }
 }
 
@@ -175,8 +192,8 @@ extension _ProvidePropertyWrapper: OptionalBasedProvideProperty where Value: Any
         }
     }
 
-    func clearValues() {
-        spezi?.handleCollectedValueRemoval(for: id, of: Value.Wrapped.self)
+    func clearValues(isolated: Bool) {
+        performClear(isolated: isolated, of: Value.Wrapped.self)
     }
 }
 

Sources/Spezi/Capabilities/Communication/StorageValueCollector.swift

@@ -16,6 +16,7 @@ import SpeziFoundation
 protocol StorageValueCollector: SpeziPropertyWrapper {
     /// This method is called to retrieve all the requested values from the given ``SpeziStorage`` repository.
     /// - Parameter repository: Provides access to the ``SpeziStorage`` repository for read access.
+    @MainActor
     func retrieve<Repository: SharedRepository<SpeziAnchor>>(from repository: Repository)
 }
 
@@ -25,6 +26,7 @@ extension Module {
         retrieveProperties(ofType: StorageValueCollector.self)
     }
 
+    @MainActor
     func injectModuleValues<Repository: SharedRepository<SpeziAnchor>>(from repository: Repository) {
         for collector in storageValueCollectors {
             collector.retrieve(from: repository)

Sources/Spezi/Capabilities/Communication/StorageValueProvider.swift

@@ -16,6 +16,7 @@ import SpeziFoundation
 protocol StorageValueProvider: SpeziPropertyWrapper {
     /// This method is called to collect all provided values into the given ``SpeziStorage`` repository.
     /// - Parameter repository: Provides access to the ``SpeziStorage`` repository.
+    @MainActor
     func collect<Repository: SharedRepository<SpeziAnchor>>(into repository: inout Repository)
 }
 
@@ -25,6 +26,7 @@ extension Module {
         retrieveProperties(ofType: StorageValueProvider.self)
     }
 
+    @MainActor
     func collectModuleValues<Repository: SharedRepository<SpeziAnchor>>(into repository: inout Repository) {
         for provider in storageValueProviders {
             provider.collect(into: &repository)

Sources/Spezi/Capabilities/Lifecycle/LifecycleHandler.swift

@@ -138,28 +138,22 @@ public protocol LifecycleHandler {
 )
 extension LifecycleHandler {
 #if os(iOS) || os(visionOS) || os(tvOS)
-    // A documentation for this method exists in the `LifecycleHandler` type which SwiftLint doesn't recognize.
-    // swiftlint:disable:next missing_docs
+    /// Empty default implementation.
     public func willFinishLaunchingWithOptions(_ application: UIApplication, launchOptions: [UIApplication.LaunchOptionsKey: Any]) {}
 
-    // A documentation for this method exists in the `LifecycleHandler` type which SwiftLint doesn't recognize.
-    // swiftlint:disable:next missing_docs
+    /// Empty default implementation.
     public func sceneWillEnterForeground(_ scene: UIScene) { }
 
-    // A documentation for this method exists in the `LifecycleHandler` type which SwiftLint doesn't recognize.
-    // swiftlint:disable:next missing_docs
+    /// Empty default implementation.
     public func sceneDidBecomeActive(_ scene: UIScene) { }
 
-    // A documentation for this method exists in the `LifecycleHandler` type which SwiftLint doesn't recognize.
-    // swiftlint:disable:next missing_docs
+    /// Empty default implementation.
     public func sceneWillResignActive(_ scene: UIScene) { }
 
-    // A documentation for this method exists in the `LifecycleHandler` type which SwiftLint doesn't recognize.
-    // swiftlint:disable:next missing_docs
+    /// Empty default implementation.
     public func sceneDidEnterBackground(_ scene: UIScene) { }
 
-    // A documentation for this method exists in the `LifecycleHandler` type which SwiftLint doesn't recognize.
-    // swiftlint:disable:next missing_docs
+    /// Empty default implementation.
     public func applicationWillTerminate(_ application: UIApplication) { }
 #endif
 }

Sources/Spezi/Capabilities/Notifications/RegisterRemoteNotificationsAction.swift

@@ -10,7 +10,7 @@ import SpeziFoundation
 import SwiftUI
 
 
-private final class RemoteNotificationContinuation: DefaultProvidingKnowledgeSource {
+private final class RemoteNotificationContinuation: DefaultProvidingKnowledgeSource, Sendable {
     typealias Anchor = SpeziAnchor
 
     static let defaultValue = RemoteNotificationContinuation()

Sources/Spezi/Capabilities/Observable/EnvironmentAccessible.swift

@@ -32,7 +32,7 @@ public protocol EnvironmentAccessible: AnyObject, Observable {}
 
 
 extension EnvironmentAccessible {
-    var viewModifierInitialization: any ViewModifierInitialization {
-        ModelModifierInitialization(model: self)
+    @MainActor var viewModifier: any ViewModifier {
+        ModelModifier(model: self)
     }
 }

Sources/Spezi/Capabilities/Observable/ModelPropertyWrapper.swift

@@ -50,7 +50,11 @@ public class _ModelPropertyWrapper<Model: Observable & AnyObject> {
 
 
     deinit {
-        clear()
+        // mirrors implementation of clear, however in a compiler proven, concurrency safe way (:
+        collected = false
+        Task { @MainActor [spezi, id] in
+            spezi?.handleViewModifierRemoval(for: id)
+        }
     }
 }
 
@@ -61,6 +65,7 @@ extension _ModelPropertyWrapper: SpeziPropertyWrapper {
         spezi?.handleViewModifierRemoval(for: id)
     }
 
+
     func inject(spezi: Spezi) {
         self.spezi = spezi
     }
@@ -97,15 +102,15 @@ extension Module {
 
 
 extension _ModelPropertyWrapper: ViewModifierProvider {
-    var viewModifierInitialization: (any ViewModifierInitialization)? {
+    var viewModifier: (any ViewModifier)? {
         collected = true
 
         guard let storedValue else {
             assertionFailure("@Model with type \(Model.self) was collected but no value was provided!")
             return nil
         }
 
-        return ModelModifierInitialization(model: storedValue)
+        return ModelModifier(model: storedValue)
     }
 
     var placement: ModifierPlacement {

Sources/Spezi/Capabilities/ViewModifier/ModifierPropertyWrapper.swift

@@ -48,7 +48,11 @@ public class _ModifierPropertyWrapper<Modifier: ViewModifier> {
     }
 
     deinit {
-        clear()
+        // mirrors implementation of clear, however in a compiler proven, concurrency safe way (:
+        collected = false
+        Task { @MainActor [spezi, id] in
+            spezi?.handleViewModifierRemoval(for: id)
+        }
     }
 }
 
@@ -97,14 +101,14 @@ extension Module {
 
 
 extension _ModifierPropertyWrapper: ViewModifierProvider {
-    var viewModifierInitialization: (any ViewModifierInitialization)? {
+    var viewModifier: (any ViewModifier)? {
         collected = true
 
         guard let storedValue else {
             assertionFailure("@Modifier with type \(Modifier.self) was collected but no value was provided!")
             return nil
         }
 
-        return WrappedViewModifier(modifier: storedValue)
+        return storedValue
     }
 }

Sources/Spezi/Capabilities/ViewModifier/ViewModifierProvider.swift

@@ -9,6 +9,7 @@
 import OrderedCollections
 import SwiftUI
 
+
 enum ModifierPlacement: Int, Comparable {
     case regular
     case outermost
@@ -28,7 +29,7 @@ protocol ViewModifierProvider {
     /// The view modifier instance that should be injected into the SwiftUI view hierarchy.
     ///
     /// Does nothing if `nil` is provided.
-    var viewModifierInitialization: (any ViewModifierInitialization)? { get }
+    @MainActor var viewModifier: (any ViewModifier)? { get }
 
     /// Defines the placement order of this view modifier.
     ///
@@ -48,13 +49,14 @@ extension ViewModifierProvider {
 
 extension Module {
     /// All SwiftUI `ViewModifier` the module wants to modify the global view hierarchy with.
-    var viewModifierEntires: [(UUID, any ViewModifierInitialization)] {
+    @MainActor
+    var viewModifierEntires: [(UUID, any ViewModifier)] {
         retrieveProperties(ofType: ViewModifierProvider.self)
             .sorted { lhs, rhs in
                 lhs.placement < rhs.placement
             }
             .compactMap { provider in
-                guard let modifier = provider.viewModifierInitialization else {
+                guard let modifier = provider.viewModifier else {
                     return nil
                 }
                 return (provider.id, modifier)