The HIG is still good

Written by Duncan Wilcox
on April 7, 2008

Inside Macintosh

The “Inside Macintosh” book series, started in 1985, is without doubt a milestone in the modern computing experience, and not just on the Mac.

Inside Macintosh was largely a reference to what has today become Carbon. Part of the first volume was what has become the Human Interface Guidelines. The main goal of the HIG was to push applications towards a consistent appearance and behaviour. What is remarkable, and what still defines the Mac user experience today, is that Mac developers have pretty consistently adhered to the HIG.

Apple Human Interface Guidelines; Part 1: Application Design Fundamentals (10%); Part 2: The Macintosh Experience (9%); Part 3: The Aqua Interface (81%)

The current Human Interface Guidelines is a three part document: “Application Design Fundamentals”, “The Macintosh Experience” and “The Aqua Interface”. The first two, a fifth of the content, largely pertain to the design process and common sense application design issues. The third part, over 80% of the content, is a very specific and detailed set of guidelines on the purpose, interaction and visuals of the elements of the Aqua UI.

In the 23 years since the first Inside Macintosh much has changed in the Mac look and feel, but I believe a turning point in the evolution of the HIG was the development of iLife around 2002-2003. Apple engineers and designers experiment outside of the sanctioned guidelines. Apple is continuously pushing the envelope beyond HIG conformance out of necessity, to innovate and refresh the look and feel, and iLife was and is the testbed for this.


Extending the Interface

In “Extending the Interface”, the guidelines leave the door open for extensions to the Aqua UI: “When a need arises that can’t be met by the standard elements, you can extend the set of controls […]”. So you’re violating the HIG only if you’re extending the interface when a standard element would meet the needs of the UI you’re implementing.


In the context of solving user needs, this explains why for example Aperture and Final Cut use grayscale controls and translucent (“HUD”) panels: standard controls and panels create visual noise that interferes with the perception of color of the actual content the application is trying to render. But does it also explain the iPhoto toolbar location? The iTunes 7 dark scrollbar look?

A reasonable argument might be that while Apple is technically violating the current HIG, they aren’t violating future guidelines: system-provided controls and frameworks, and the guidelines themselves, will eventually be updated to reflect the innovation.

What should a third party developer do? John Gruber’s C4[0] talk “Consistency vs. Uniformity in UI Design” spurred some debate and spread the “the HIG is dead!” meme.

A guideline is not a hard rule, and the HIG is open to extensions when “a need arises” anyway. I can’t help thinking that while there are important details regarding what Aqua controls should look like, they are still only details. If you look at any productivity app, you’ll find that the major part of the UI is composed of elements that are impossible to codify in guidelines.

The image editor view of Acorn, Pixelmator, Photoshop? The spreadsheet and charts editor in Numbers and Excel? The waveform view in FuzzMeasure, Fission or Logic? Clearly the visualization and the interaction depend on the nature of the data, and while there are several types of data that have natural or established visual mappings, interaction and editing are a whole other can of worms. This is where developers spend a lot of their coding time, and take the tough decisions that make or break the app.

An application with visually distinctive window style or control look will never stand a chance against an application with distinctive data visualization and interaction. As JLG once put it, “At a risk of being called sexist, ageist and French, if you put multimedia, a leather skirt and lipstick on a grandmother and take her to a nightclub, she’s still not going to get lucky” — he was referring to Windows 98 at the time, but it’s a timeless quote.


Visual user interfaces

Now imagine you’re John Geleynse (oh perhaps you are — hi John!), you desperately want to help Mac developers build better apps, you’ve covered the use of system-provided user interface elements, now what? The closest to describing what goes in the main content view is probably the “Reflect the User’s Mental Model” section in the “Human Interface Design Principles” chapter. Good, solid principles, but kinda fuzzy when you’re trying to build a new UI.


The Apple Human Interface Guidelines never covered the hardest part of building user interfaces, beyond general high level design principles. What’s changing now is what is a good versus merely acceptable user interface:

… and so on.

Many apps already expose core content data visually. For many of the apps that don’t, the future is for the standard controls-based UI to be replaced with application specific graphic design and interaction design, packaged in a custom view with contextual editing controls and direct manipulation.

Edward Tufte’s work on information visualization is a great source of inspiration, I believe the main view of many apps could be implemented as interactive Tufteian graphics. Bret Victor dissects this process in his amazing Magic Ink essay, where he describes how he built the user interface for the award-winning BART widget (pictured above).

In my experience Apple UI people are quite helpful in anything from brainstorming to refining UI concepts, for example in the WWDC labs and UI design sessions. However, discussions inevitably are on a case by case basis. It has become apparent that building a high quality app on the Mac now requires having a designer on the team.


Visceral user interfaces

How has GUI interaction evolved? Let’s put a square on screen:

I love my iPhone

Each step removes a little bit of abstraction and a little bit of indirection, until interaction is natural, because while technically there is an interface, you’re manipulating the content with your hand and you don’t feel like there’s an intermediary.

And by the way the relevant part of the iPhone HIG is pretty much similar to the corresponding Mac OS X HIG section.


Is it dead?

The HIG is still good. In fact the first fifth of it is pure gold, still 100% current and relevant. The Aqua guidelines are just less relevant to applications where user interaction and data representation are tightly coupled, where content and UI aren’t separated by indirection, where interaction is more visceral, where the content is the user interface.



About the Author

Hi, I’m Duncan Wilcox, I’m a software developer and chocolate addict, living in Florence, Italy. I’m passionate about the Mac, photography and user interaction, among other things. Contact me at or follow me on Twitter. These days I work on Sparkle.