Hex viewer

[davedelong]

This adds a hex viewer to Pasteboard Viewer and fixes #24.

This uses the HexFiend framework to add a hex viewer to the app, which can be accessed by toggling a picker in the toolbar.

Some things to note:

• This depends on the package branch of the HexFiend project, as that is the branch that adds a Package.swift file. It is technically unreleased, although it appears to be fully functional.
• The format of the "extra info" in the toolbar is meant to mimic the format shown in the Hex Fiend app as closely as possible.
• Selection is not preserved when toggling between text and hex modes.

[sindresorhus]

Thanks for working on this! This is already looking pretty good.

• You need to if-def it out for iOS.
• The selection needs to be reset when the pasteboard changes.
  • I also think it makes sense to reset the selection when switching between pasteboard items.
• I noticed it's quite slow to select something when viewing an image. Not sure if the problem is the framework or the wrapper code.
• Would be useful to have the text/hex picker in the "View" menu bar menu too, with keyboard shortcuts. But not a requirement for this pull request.

[davedelong]

• I noticed it's quite slow to select something when viewing an image. Not sure if the problem is the framework or the wrapper code.

I took a quick look at this in instruments, and from what I can tell there's an identical spike when showing the text view as showing the hex view. I'm reasonably confident that this is down to retrieving the type.data() from the pasteboard to provide to the UI. There's probably an optimization that could be made there around caching it once it's been read, so that subsequent calls to .data() are instantaneous.

[davedelong]

Besides the hiccup when showing large datas (like images), all the other feedback has been addressed, including adding the ⌘1 and ⌘2 switcher in the View menu. 😃

[davedelong]

(I also confirmed that the branch builds cleanly for iOS)

[sindresorhus]

Looks great 🙌

[sindresorhus]

Update submitted.