Allow app to access Files app by creating its own app folder using the FileManager framework

Files.swift

/**
  Step 1: info.plist, set:
  UIFileSharingEnabled = YES
  LSSupportsOpeningDocumentsInPlace = YES
 */

/**
  Step 2: I used a pod that is a thin wrapper over FileManager, created by Sundell
  Podfile, set
  pod 'Files', '~> 4.0.2'
 */

/**
  Step 3: In AppDelegate
 */
import Files // Files pod by Sundell

// Access the document directory using FileManager
let docsDirUrl = try! FileManager.default.url(for: .documentDirectory,
                                              in: .userDomainMask,
                                              appropriateFor: nil,
                                              create: true)

// Using files, access the document folder by using its folder url path
let docsFolder = try! Folder(path: docsDirUrl.path)
// Check if the docs folder has a subfolder for the app name
if docs.constainsSubfolder(named: App.displayName) {
  // If it does, make sure a folder is printed with the App.displayName
  docs.subfolders.recursive.forEach { print($0.name) }
} else {
  let appFolder = try! docs.createSubfolder(named: App.displayName)
  // Make sure a folder is printed with the App.displayName
  docs.subfolders.recursive.forEach { print($0.name) }
}