UserDefaults Wrapper with Generic Keys (swift)

DefaultKey.swift

//
//  DefaultKey.swift
//
//  Created by Kellen Styler on 9/9/19.
//


/// Default Key -Used by Defaults for keyed values
public struct DefaultKey<DefaultType> {
    
    // MARK: Properties
    
    let name: String
    
    
    // MARK: Lifecycle
    
    /// Init with name and initial value
    ///
    /// - Parameters:
    ///   - name: String
    ///   - initialValue: Any
    public init(_ name: String, initialValue: Any) {
        self.name = name
        
        // Register the initial value
        Defaults.registerValue(initialValue, forKeyName: name)
    }
}


// MARK: - Equatable

extension DefaultKey: Equatable {
    
    public static func ==<T>(lhs: DefaultKey<T>, rhs: DefaultKey<T>) -> Bool {
        return lhs.name == rhs.name
    }
}

Defaults.swift

//
//  Defaults.swift
//
//  Created by Kellen Styler on 9/10/19.
//


/// Defaults -UserDefaults wrapper
final public class Defaults {

    // MARK: Public
    
    /// Get Value for key
    ///
    /// - Parameter key: DefaultKey<DefaultType>
    /// - Returns: DefaultType
    public static func getValue<DefaultType>(for key: DefaultKey<DefaultType>) -> DefaultType {
        synchronize()
        
        return standard.value(forKey: key.name) as! DefaultType
    }
    
    /// Register Value for key name
    /// - NOTE: `forKeyName` is a string value to allow registration during init
    ///         of `DefaultKey`s.
    ///
    /// - Parameters:
    ///   - value: DefaultType
    ///   - name: String
    public static func registerValue<DefaultType>(_ value: DefaultType, forKeyName name: String) {
        standard.register(defaults: [name: value])
        synchronize()
    }
    
    /// Set Value for key
    ///
    /// - Parameters:
    ///   - value: DefaultType?
    ///   - key: DefaultKey<DefaultType>
    public static func setValue<DefaultType>(_ value: DefaultType?, for key: DefaultKey<DefaultType>) {
        
        // Set
        if let value = value {
            standard.setValue(value, forKey: key.name)
            synchronize()
        }
        
        // Clear if nil
        else {
            clearValue(for: key)
        }
    }
}


// MARK: - Private Helpers

fileprivate extension Defaults {
    
    // MARK: Static Properties
    
    static var standard = UserDefaults.standard
    
    
    // MARK: Static Methods
    
    /// Synchronize
    static func synchronize() {
        standard.synchronize()
    }
}


// MARK: - Private Extension

fileprivate extension Defaults {
    
    /// Clear Value for key
    ///
    /// - Parameter key: DefaultKey<DefaultType>
    static func clearValue<DefaultType>(for key: DefaultKey<DefaultType>) {
        standard.removeObject(forKey: key.name)
        synchronize()
    }
}

YouDefaultKeyExtension.swift

// MARK: - Your DefaultKey Extention

public extension DefaultKey {
    static var yourKeyName: DefaultKey<Date> { return DefaultKey<Date>("your_key_name", initialValue: Date.distantPast) }
}

// Just simply create your keys like shown above.  
// Then, use them like so:

Defaults.setValue(Date.distantPast, for: .yourKeyName)
let yourKeyValue = Defaults.getValue(for: .yourKeyName)