UserDefaults Key with a Property Wrapper

UserDefaultsKey.swift

import Foundation

// MARK:- Usage

extension UserDefaults.Key where Value == Bool {
    static let shouldDoSomething = Self(name: "shouldDoSomething", default: false)
}

struct View {

    @UserDefault(key: .shouldDoSomething) private var shouldDoSomething

    func f() {

        guard shouldDoSomething else { return }

        // DO SOMETHING
    }
}

// MARK:- UserDefault Property Wrapper

@propertyWrapper
public final class UserDefault<Value> {

    private let defaults: UserDefaults
    private let key: UserDefaults.Key<Value>

    public init(key: UserDefaults.Key<Value>, defaults: UserDefaults = .standard) {
        self.defaults = defaults
        self.key = key
    }

    public var wrappedValue: Value {
        get { defaults.value(for: key) ?? key.default }
        set { defaults.set(newValue, for: key) }
    }
}

// MARK:- UserDefaults Key

extension UserDefaults {

    /// A wrapper around a user defaults key, to enable a type-safe
    /// way of accessing values in an instance of UserDefaults.
    public struct Key<Value> {
        fileprivate let name: String
        fileprivate let `default`: Value
        public init(name: String, default: Value) {
            self.name = name
            self.default = `default`
        }
    }

    /// Sets the value of the specified key.
    ///
    /// - Parameters:
    ///   - value: The value to store in the defaults database.
    ///   - key: The key with which to associate the value.
    public func set<Value>(_ value: Value?, for key: UserDefaults.Key<Value>) {
        set(value, forKey: key.name)
    }

    /// Returns the value associated with the specified key.
    ///
    /// - Parameter key: The key which is associated with the value.
    /// - Returns: The value associated with the specified key, or nil if the key was not found.
    public func value<Value>(for key: UserDefaults.Key<Value>) -> Value? {
        return object(forKey: key.name) as? Value
    }

    /// Removes the value of the specified key.
    ///
    /// - Parameter key: The key whose value you want to remove.
    public func remove<Value>(for key: UserDefaults.Key<Value>) {
        removeObject(forKey: key.name)
    }
}