Negative for Mac – a simple PDF reader for night owls

Finally you can read your e-books and e-textbooks in PDFs after dark without tiring your eyes.

The history of its creation is linked to my own attempts to learn Swift. For more than two years, I had been learning Swift primarily from textbooks by Paul Hudson (Hacking with Swift), Simon Ng (Appcoda) and those published by Most of them are available in various formats: ePub, PDF, and even Mobi for e-book readers.

I tested various formats and I know that for programming textbooks, in which fragments of code are presented on almost every page, static, rigidly stacked PDFs are best suited. In the case of ePubs, the code is often wrapped or truncated if the font is too large. Learning to program from a Kindle textbook is also very uncomfortable.

PDFs worked for me the best. Unfortunately, they have one drawback. It’s not possible to change their parameters, which bothers me especially when I’m learning after dark. For almost two years, my eyes were tormented by the white background pages of such textbooks. Reducing the brightness of the display on a Mac or iPad did not give much. It always shone too brightly.

Manuals in the ePub format, opened in iBooks on a Mac or iPad (or finally on an iPhone) allow you to change colors, enable night mode, but problems with the correct display of the code (I have mentioned above) disqualified this solution. Obviously, I could reverse colors in the entire operating system, but that would be desperation (in fact most programs offer dark mode, also a code editor in Xcode).

So I was looking for a PDF reader for Mac that would offer color inversion and unfortunately I did not find it. So I decided to write myself a PDF reader for Mac for night owls like me. I have done it with help of much more experienced Swift developer – Marcin Maciukiewicz.

Negative has three working modes:

  • Normal – no inverted colors. In this way, you can open documents to yourself, for example, in Preview on Mac
  • Inverted – here the colors are just reversed, everything is in reverse
  • Inverted with Sepia – the picture in the negative with the sepia added, which in my opinion further improves the comfort of reading in the dark.

Each of the modes is activated one after the other, like on a carousel, after next clicking on the button with the eye on the toolbar.

On the toolbar you will also find a field for entering the page number to which you want to jump.

You can also toggle colour of the toolbar between light and dark.

There is still a lot to do:

  • adding a vertical navigation window with page thumbnails in the document, as in the MacOS Preview
  • remembering the last page open for the document so that it opens directly on it
  • adding bookmarks
  • improvement of the interface (I do not have experience in this topic, therefore Negative is deprived of UX spurts).