Swift 3 object to JSON file layer

JSONPersistence.swift

//
//  JSONPersistence.swift
//  Fobo
//
//  Created by Lacy Rhoades on 7/11/17.
//  Copyright © 2017 Colordeaf. All rights reserved.
//

import Foundation
import SwiftyJSON

protocol Initializeable {
    init()
}

protocol JSONMappable {
    static func decode(json: JSON) -> Self?
    static func encode(_ object: Self) -> JSON
}

protocol JSONPersistable {
    static var persistenceFileName: String { get }
    static var persistenceURL: URL { get }
    func didLoad()
    func didPersist()
}

extension JSONPersistable {
    static var persistenceURL: URL {
        return FileManager()
            .urls(for: .documentDirectory, in: .userDomainMask)
            .first!
            .appendingPathComponent(
                self.persistenceFileName.appending(".json")
        )
    }
    
    func didLoad() {
    }
    
    func didPersist() {
    }
}

extension JSONPersistable where Self: JSONMappable, Self: Initializeable {
    static func load() -> Self {
        var result: Self
        
        if let fileData = FileManager().contents(atPath: persistenceURL.path),
            let stored = Self.decode(json: JSON(data: fileData)) {
            result = stored
        } else {
            result = Self()
        }
        
        result.didLoad()
        
        return result
    }
    
    static func persist(_ instance: Self) {
        let url = Self.persistenceURL
        let data = Self.encode(instance).rawString(.utf8)?.data(using: .utf8)

        let _ = FileManager().createFile(atPath: url.path, contents: data, attributes: nil)

        do {
            try data?.write(to: url)
            dl("JSONPersistable", "Wrote")
            instance.didPersist()
        } catch {
            dl("JSONPersistable", "Error")
        }
    }
}