Learning Swift, 2nd Edition

Chapter 6. User Interfaces and iCloud

In its current state, our note-taking app for macOS allows you to view and edit the text in documents. In this chapter, we’ll add the ability to work with attachments, and then we’ll add support for iCloud.

First, we’ll add support for the general concept of attachments—that is, attaching arbitrary files to a notes document, including the user interface; and then we’ll expand it, adding support for double-clicking attachments to open them, including attachments that represent a real-world location, and dragging and dropping files on notes to attach them. We’ll also add support for Quick Look on our notes file format, allowing users to view the contents of a note from within the macOS Finder.

As you learned in “Package File Formats”, when we set up the file wrappers for this app, attachments are stored in the document’s Attachments directory. This means that the Document class needs tools for working with the contents of this directory. It also needs an interface for presenting the attachments and a method of adding new attachments.

In this chapter, we’ll use NSCollectionView, some more advanced features of FileWrapper, and NSOpenPanel to select files to add as attachments. The NSCollectionView and NSOpenPanel classes are advanced user interface elements of macOS that will allow you to present a grid or list of data, and allow users to pick files from the filesystem for use in your app, respectively.

Updating the UI

The first thing we need ...