DataManager.swift

import UIKit

class DataManager{
    //Documentに関する情報
    struct MyDocInfo{
        static let NAME = "document"
        static let ECTENSION = "doc"
        static var LOCAL_DOCUMENTS_PATH:String? = nil
    }
    //アプリのサンドボックスのパスを格納する変数
    var localDocumentsPath:String{
        if let dir = MyDocInfo.LOCAL_DOCUMENTS_PATH{
            return dir
        }else {
            let dir = NSSearchPathForDirectoriesInDomains(.documentDirectory,.userDomainMask, true)[0] + "/"
            MyDocInfo.LOCAL_DOCUMENTS_PATH = dir
            return dir
        }
    }
    
    func openDocument(completion:@escaping (MyDocument)->()){
        let filePath = localDocumentsPath + MyDocInfo.NAME + "." + MyDocInfo.ECTENSION
        let fileURL = URL(fileURLWithPath:filePath)
        //ファイルの存在チェック
        let isFileExists = FileManager.default.fileExists(atPath: filePath)
        let document = MyDocument(fileURL:fileURL)
        if isFileExists{
            document.open { (isSuccess) in
                if isSuccess{
                    print("Documentを開きましたtext\(document.text!):\(document.date!)")
                    completion(document)
                }else{
                    print("Documentを開けませんでした。")
                }
            }
        }else {
            print("ファイルがありません")
        }
    }
    
    func saveDocument(text:String,date:Date,completion:@escaping ()->()) {
        let filePath = localDocumentsPath + MyDocInfo.NAME + "." + MyDocInfo.ECTENSION
        let fileURL = URL(fileURLWithPath:filePath)
        let document = MyDocument(fileURL:fileURL)
        
        //ここで保存したい内容を書く
        document.text = text
        document.date = date
        
        document.save(to: fileURL, for: .forCreating) { (isSuccess) in
            if isSuccess{
                print("Documentを保存しました。text\(document.text)")
                completion()
            }else{
                print("Documentを保存できませんでした")
            }
        }
    }
    
    func saveDocument(text:String,date:Date,img:UIImage,images:[UIImage],completion:@escaping ()->() ){
        
        let filePath = localDocumentsPath + MyDocInfo.NAME + "." + MyDocInfo.ECTENSION
        let fileURL = URL(fileURLWithPath:filePath)
        let document = MyDocument(fileURL:fileURL)
        
        //ここで保存したい内容を書く
        document.text = text
        document.date = date
        document.img = img
        document.images = images
        
        document.save(to: fileURL, for: .forCreating) { (isSuccess) in
            if isSuccess{
                print("Documentを保存しました。text\(document.text)")
                completion()
            }else{
                print("Documentを保存できませんでした")
            }
        }
    }
}

MyDocument.swift

import UIKit

class MyDocument: UIDocument {
    //各データに対応したStatic定数を宣言
    struct Keys{
        static let IMG = "MyDocument.img"
        static let TEXT = "MyDocument.text"
        static let DATE = "MyDocument.date"
        static let IMAGES = "MyDocument.imgarray"
    }
    
    //記録したい内容を保持するメンバ変数を宣言
    var img:UIImage!
    var text:String!
    var date:Date!
    var images:[UIImage]!
    
    //上記の内容をひとまとめにするNSFileWrapper
    var fileWrapper:FileWrapper?
    
    override func load(fromContents contents: Any, ofType typeName: String?) throws {
        //引数で渡されたcontentsをダウンキャストし、fileWrapperにつめる。
        if let fileWrapper = contents as? FileWrapper {
            self.fileWrapper = fileWrapper
            let dict = fileWrapper.fileWrappers
            
            if let fw = dict![Keys.IMG] as FileWrapper?,
                let contents = fw.regularFileContents{
                self.img = UIImage(data:contents)
            }
            if let fw = dict![Keys.TEXT] as FileWrapper?,
                let contents = fw.regularFileContents{
                self.text = String(data:contents,encoding:String.Encoding(rawValue: String.Encoding.utf8.rawValue))
            }
            if let fw = dict![Keys.DATE] as FileWrapper?,
                let contents = fw.regularFileContents{
                self.date = NSKeyedUnarchiver.unarchiveObject(with: contents) as! Date
            }
            if let fw = dict![Keys.IMAGES] as FileWrapper?,let contents = fw.regularFileContents{
                self.images = NSKeyedUnarchiver.unarchiveObject(with: contents) as! [UIImage]
            }
        }
    }
    
    override func contents(forType typeName: String) throws -> Any {
        if self.fileWrapper == nil{
            //空のディクショナリを渡す
            self.fileWrapper = FileWrapper(directoryWithFileWrappers: [:])
        }
        if let text = self.text,
            let data = text.data(using: String.Encoding.utf8){
            let fw = FileWrapper(regularFileWithContents: data)
            fw.preferredFilename = Keys.TEXT
            self.fileWrapper?.addFileWrapper(fw)
        }
        if let img = self.img,
            let data  = UIImageJPEGRepresentation(img, 1.0){
            let fw = FileWrapper(regularFileWithContents: data)
            fw.preferredFilename = Keys.IMG
            self.fileWrapper?.addFileWrapper(fw)
        }
        if let date = self.date{
            let data = NSKeyedArchiver.archivedData(withRootObject: date)
            let fw = FileWrapper(regularFileWithContents: data)
            fw.preferredFilename = Keys.DATE
            self.fileWrapper?.addFileWrapper(fw)
        }
        if let images = self.images{
            let data = NSKeyedArchiver.archivedData(withRootObject: images)
            let fw = FileWrapper(regularFileWithContents:data)
            fw.preferredFilename = Keys.IMAGES
            self.fileWrapper?.addFileWrapper(fw)
        }
        return self.fileWrapper!
    }

}

ViewController.swift

import UIKit

class ViewController:UIViewController {
  
    override func viewDidLoad() {
        super.viewDidLoad()

        let dataManager = DataManager()
        //Documentが保存されていれば表示
        dataManager.openDocument { (doc) in
            print(doc.text)
        }
    }
  
    @IBAction func btnTapped(_ sender: UIButton) {
        let dataManager = DataManager()
        //適当にボタンを押した時に保存
        dataManager.saveDocument(text: "hogehoge", date: Date()) {
            print("save完了!")
        }
    }
  
  
}