createDocFile.swift

  func createDocFile(fileName: String, content: String) {
        // get the document directory url
        guard let docDir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }

        // choose the location of the file to be withinthe document directory
        let fileURL = docDir.appendingPathComponent(fileName)
        print("file url: ", fileURL)

        do {
            // creating or appending to a file by writing to the file url
            print("writing data to file...")
            try content.write(to: fileURL, atomically: true, encoding: .utf8)

            // instantiate the contents of a file into an appropriate type
            let newString = try String(contentsOf: fileURL)
            print("new string: ", newString)
        } catch {
            print("data writing error \(error)")
        }
    }