UserDefaults property wrapper

DefaultsStorage.swift

public protocol AnyOptional {
    var isNil: Bool { get }
}

extension Optional: AnyOptional {
    public var isNil: Bool { self == nil }
}

@propertyWrapper
public struct DefaultsStorage<T> where T: Codable {
    let key: String
    let defaultValue: T
    let userDefaults = UserDefaults.standard

    init(_ key: String, defaultValue: T) {
        self.key = key
        self.defaultValue = defaultValue
    }

    public var wrappedValue: T {
        get {
            if let data = userDefaults.data(forKey: key) {
                let value = try? JSONDecoder().decode(T.self, from: data)
                return value ?? defaultValue
            } else {
                return defaultValue
            }
        }
        set {
            if let value = newValue as? AnyOptional, value.isNil {
                userDefaults.removeObject(forKey: key)
            } else {
                let data = try? JSONEncoder().encode(newValue)
                userDefaults.set(data, forKey: key)
            }
        }
    }
}

// see more: https://swiftbysundell.com/articles/property-wrappers-in-swift/
extension DefaultsStorage where T: ExpressibleByNilLiteral {
    init(_ key: String) {
        self.key = key
        self.defaultValue = nil
    }
}