Merge pull request #2 from amine2233/feature/usererdefaults-combine

feat: add propertywrapper to userdefaults

Author: amine2233

Sources/CombineExtensionUserDefaults/UserDefaults/CombineUserDefaultOnChange.swift

@@ -15,9 +15,9 @@ public extension Publishers {
         public typealias Failure = Never
 
         private let userDefaults: UserDefaults
-        private let key: Key
+        private let key: UserDefaultsKey
 
-        public init(userDefaults: UserDefaults, key: Key) {
+        public init(userDefaults: UserDefaults, key: UserDefaultsKey) {
             self.userDefaults = userDefaults
             self.key = key
         }
@@ -36,11 +36,11 @@ public extension Publishers {
 extension Publishers.DefaultsObservation {
     private final class SubscriptionDefaultsObservation<S: Subscriber, T: PropertyListValue>: NSObject, Subscription where S.Input == T? {
         private var subscriber: S?
-        private var key: Key
+        private var key: UserDefaultsKey
         private var isDisposed: Bool = false
         private var userDefaults: UserDefaults
 
-        init(subscriber: S, userDefaults: UserDefaults, key: Key) {
+        init(subscriber: S, userDefaults: UserDefaults, key: UserDefaultsKey) {
             self.subscriber = subscriber
             self.userDefaults = userDefaults
             self.key = key

Sources/CombineExtensionUserDefaults/UserDefaults/DefaultsObservation.swift

@@ -10,20 +10,17 @@ import Combine
 import CombineExtension
 
 final class DefaultsObservation<T: PropertyListValue>: NSObject, Cancellable {
-    let key: Key
-    private var onChange: (T?) -> Void
+    let key: UserDefaultsKey
     var isDisposed: Bool = false
     var userDefaults: UserDefaults
+    private var onChange: (T?) -> Void
 
-    init(key: Key, userDefaults: UserDefaults = .standard, onChange: @escaping (T?) -> Void) {
+    init(key: UserDefaultsKey, userDefaults: UserDefaults = .standard, onChange: @escaping (T?) -> Void) {
         self.key = key
         self.onChange = onChange
         self.userDefaults = userDefaults
-    }
-
-    func configure() -> DefaultsObservation<T> {
-        userDefaults.addObserver(self, forKeyPath: key.rawValue, options: [.new], context: nil)
-        return self
+        super.init()
+        self.userDefaults.addObserver(self, forKeyPath: key.rawValue, options: [.new], context: nil)
     }
 
     // swiftlint:disable block_based_kvo

Sources/CombineExtensionUserDefaults/UserDefaults/DefaultsStorage.swift

@@ -0,0 +1,88 @@
+//
+//  File.swift
+//  
+//
+//  Created by amine on 27/12/2022.
+//
+
+import Combine
+#if canImport(SwiftUI)
+import SwiftUI
+
+/// A property wrapper type that reflects a value from `UserDefaults` and
+/// invalidates a view on a change in value in that user default.
+@frozen @propertyWrapper
+public struct DefaultsStorage<Value: PropertyListValue>: DynamicProperty {
+
+    @ObservedObject private var _value: DefaultsObservationStorage<Value>
+
+    private init(
+        value: Value,
+        userDefaults: UserDefaults = .standard,
+        key: UserDefaultsKey
+    ) {
+        _value = DefaultsObservationStorage(
+            defaultValue: value,
+            key: key,
+            userDefaults: userDefaults
+        )
+    }
+
+    public var wrappedValue: Value {
+        get {
+            _value.value
+        }
+        nonmutating set {
+            _value.value = newValue
+        }
+    }
+
+    public var projectedValue: Binding<Value> {
+        Binding(
+            get: { self.wrappedValue },
+            set: { self.wrappedValue = $0 }
+        )
+    }
+
+    public var publisher: AnyPublisher<Value, Never> {
+        _value.publisher
+    }
+}
+
+@usableFromInline
+final class DefaultsObservationStorage<T: PropertyListValue>: NSObject, ObservableObject {
+    var defaultValue: T
+    let key: UserDefaultsKey
+    var isDisposed: Bool = false
+    var userDefaults: UserDefaults
+    var value: T {
+        get { userDefaults.value(forKey: key.rawValue) as? T ?? defaultValue }
+        set { userDefaults.setValue(newValue, forKey: key.rawValue) }
+    }
+    var publisher: AnyPublisher<T, Never> { subject.eraseToAnyPublisher() }
+
+    private var subject: CurrentValueSubject<T, Never>
+
+    init(
+        defaultValue: T,
+        key: UserDefaultsKey,
+        userDefaults: UserDefaults = .standard
+    ) {
+        self.defaultValue = defaultValue
+        self.key = key
+        self.userDefaults = userDefaults
+        self.subject = CurrentValueSubject(defaultValue)
+        super.init()
+        self.userDefaults.addObserver(self, forKeyPath: key.rawValue, options: [.new], context: nil)
+    }
+
+    // swiftlint:disable block_based_kvo
+    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey: Any]?, context _: UnsafeMutableRawPointer?) {
+        guard let change = change, object != nil, keyPath == key.rawValue else { return }
+        let newValue = change[.newKey] as? T
+        subject.send(newValue ?? defaultValue)
+    }
+    // swiftlint:enable block_based_kvo
+}
+
+#endif

Sources/CombineExtensionUserDefaults/UserDefaults/PropertyListValue.swift

@@ -10,15 +10,15 @@ import CombineExtension
 
 public protocol PropertyListValue {}
 
-public struct Key: RawRepresentable {
+public struct UserDefaultsKey: RawRepresentable {
     public let rawValue: String
 
     public init(rawValue: String) {
         self.rawValue = rawValue
     }
 }
 
-extension Key: ExpressibleByStringLiteral {
+extension UserDefaultsKey: ExpressibleByStringLiteral {
     public init(stringLiteral value: String) {
         rawValue = value
     }

Sources/CombineExtensionUserDefaults/UserDefaults/UserDefaults+Extension.swift

@@ -10,14 +10,13 @@ import Combine
 import CombineExtension
 
 extension CombineExtension where Base: UserDefaults {
-    public func change<T: PropertyListValue>(key: Key) -> AnyPublisher<T?, Never> {
+    public func change<T: PropertyListValue>(key: UserDefaultsKey) -> AnyPublisher<T?, Never> {
         Publishers.DefaultsObservation(userDefaults: base, key: key)
             .eraseToAnyPublisher()
     }
 
-    public func onChange<T:PropertyListValue>(key: Key, callback: @escaping (T?) -> Void) -> AnyCancellable {
+    public func onChange<T:PropertyListValue>(key: UserDefaultsKey, callback: @escaping (T?) -> Void) -> AnyCancellable {
         DefaultsObservation(key: key, userDefaults: base, onChange: callback)
-            .configure()
             .eraseToAnyCancellable()
     }
 }