Ticket to ride

Mon, 05 Dec 2022 00:00:00 +0000

A couple of days ago I was lauding the learning benefits of writing your own projects over completing tutorial projects - since your own projects push your boundaries further. Of course, its also the case that the project requirements might so completely exceed your current ability that it grinds to a halt. That’s the case with my behaviour ticket app.

The part of the app for collecting the data is pretty much done and how I imagined it, but the output needs to be pretty tickets that can be printed on paper. I managed to write the ticket data to a CSV file and export that to the files app with a .fileExporter, but really what I wanted is to have one of those share screens where you can chose to AirDrop, Print etc, and for the tickets to have been rendered to a PDF or series of images to be shared. That will have to wait. I’m just up to a bit in the #100Days about writing images so I’ll push on with that for a bit and come back to my app.

In the meantime, it’s worth going over how to create and export the text file briefly.

First of all, I stole this TextFile code from Paul Hudson (here) that wraps some complexity neatly into a struct.

//
// TextFile.swift
// Stolen from Paul Hudson @twostraws
// https://www.hackingwithswift.com/quick-start/swiftui/how-to-create-a-document-based-app-using-filedocument-and-documentgroup
//

import SwiftUI
import UniformTypeIdentifiers

struct TextFile: FileDocument {
 // tell the system we support only plain text
 static var readableContentTypes = [UTType.plainText]

 // by default our document is empty
 var text = ""

 // a simple initializer that creates new, empty documents
 init(initialText: String = "") {
 text = initialText
 }

 // this initializer loads data that has been saved previously
 init(configuration: ReadConfiguration) throws {
 if let data = configuration.file.regularFileContents {
 text = String(decoding: data, as: UTF8.self)
 } else {
 throw CocoaError(.fileReadCorruptFile)
 }
 }

 // this will be called when the system wants to write our data to disk
 func fileWrapper(configuration: WriteConfiguration) throws -> FileWrapper {
 let data = Data(text.utf8)
 return FileWrapper(regularFileWithContents: data)
 }
}

Now here’s all the modifiers I’ve got attached to the list of tickets.

The toolbar button just assigns a string to the instance of Paul’s TextFile(). The string is built by just stepping through the tickets in a for loop and appending csv strings for each ticket to the big string that becomes the file.

The .fileExporter then does the heavy lifting. It slides up a view of the files in the “On My Phone” folder, lets the user name the file and saves it.

 .navigationTitle("Tickets")
 .fileExporter(isPresented: $showingExporter, document: exportFile, contentType: .plainText) { result in
 switch result {
 case .success(let url):
 print("Saved to \(url)")
 case .failure(let error):
 print(error.localizedDescription)
 }
 }
 .toolbar {
 Button {
 exportFile.text = ticketsExportText()
 showingExporter = true
 } label: {
 Image(systemName: "square.and.arrow.up")
 .padding(.horizontal)
 }
 }

Ticket-App on blog.iankulin.com

Ticket to ride