add @LocalStorageEntry property wrapper

Sources/SpeziLocalStorage/LocalStorage.swift

@@ -130,6 +130,7 @@ public final class LocalStorage: Module, DefaultInitializable, EnvironmentAccess
 
         try encryptedData.write(to: fileURL)
         try setResourceValues()
+        key.publisher.send(value)
     }
 
 
@@ -199,6 +200,7 @@ public final class LocalStorage: Module, DefaultInitializable, EnvironmentAccess
         if fileManager.fileExists(atPath: fileURL.path) {
             do {
                 try fileManager.removeItem(atPath: fileURL.path)
+                key.publisher.send(nil)
             } catch {
                 throw LocalStorageError.deletionNotPossible
             }

Sources/SpeziLocalStorage/LocalStorageEntry.swift

@@ -0,0 +1,49 @@
+//
+// This source file is part of the Stanford Spezi open-source project
+//
+// SPDX-FileCopyrightText: 2025 Stanford University and the project authors (see CONTRIBUTORS.md)
+//
+// SPDX-License-Identifier: MIT
+//
+
+import Combine
+import SwiftUI
+
+
+/// Access ``LocalStorage`` entries within a SwiftUI View.
+@propertyWrapper
+public struct LocalStorageEntry<Value>: DynamicProperty {
+    private let key: LocalStorageKey<Value>
+
+    @Environment(LocalStorage.self) private var localStorage
+    @State private var internals = LocalStorageEntryInternals<Value>()
+
+    public init(_ key: LocalStorageKey<Value>) {
+        self.key = key
+    }
+
+    public func update() {
+        internals.subscribe(to: key, in: localStorage)
+    }
+
+    public var wrappedValue: Value? {
+        get { internals.value }
+        set { try? localStorage.store(newValue, for: key) }
+    }
+}
+
+
+@Observable private final class LocalStorageEntryInternals<Value> {
+    fileprivate var value: Value?
+
+    @ObservationIgnored
+    private var cancellable: AnyCancellable?
+
+    func subscribe(to key: LocalStorageKey<Value>, in localStorage: LocalStorage) {
+        cancellable?.cancel()
+        cancellable = key.publisher.sink { [weak self] newValue in
+            self?.value = newValue
+        }
+        value = try? localStorage.load(key)
+    }
+}

Sources/SpeziLocalStorage/LocalStorageKey.swift

@@ -6,7 +6,7 @@
 // SPDX-License-Identifier: MIT
 //
 
-import Dispatch
+import Combine
 import Foundation
 import SpeziFoundation
 
@@ -70,6 +70,7 @@ public final class LocalStorageKey<Value>: LocalStorageKeys, @unchecked Sendable
     let encode: @Sendable (Value) throws -> Data
     let decode: @Sendable (Data) throws -> Value?
     private let lock = RWLock()
+    let publisher = PassthroughSubject<Value?, Never>()
 
     /// Creates a Local Storage Key that uses custom encoding and decoding functions.
     public init(
@@ -101,7 +102,7 @@ extension LocalStorageKey {
     }
 
     /// Creates a Local Storage Key that uses a custom encoder and decoder.
-    public convenience init<E: TopLevelEncoder & Sendable, D: TopLevelDecoder & Sendable>(
+    public convenience init<E: SpeziFoundation.TopLevelEncoder & Sendable, D: SpeziFoundation.TopLevelDecoder & Sendable>(
         _ key: String,
         setting: LocalStorageSetting = .default, // swiftlint:disable:this function_default_parameter_at_end
         encoder: E,