Rather than attempting to eliminate error cases, use your iterative design process to understand failure modes and design for them. You should seek to understand failure cases in two ways. First, to identify whether an ‘escalation’ or executive judgment is required. In certain cases such as fraud detection, a user that attempts to correct an erroneous fraud label needs a streamlined way to do so, as these exceptional cases can be highly stressful! Second, you can use iterative design to better understand your own criterion of success. Many problems don’t have a binary true-false answer. Sometimes, in cases such as recommendation, quality follows a gradient from terrible to excellent.
A design language is a standard way to communicate a set of concepts so that people don’t have to re-learn things over and over. They make roads easier to drive on, kitchen utensils easier to use, and technology more intuitive. Every time you tap on a button on a website and see the button change color to signal that you ‘clicked’ it, you’re interfacing with a design language. Design can bring clarity, intuition, and usability to these kinds of experiences. But more importantly, design is a lens with which we should make change in the world.
Like many things in UI design, something that appears random and subjective (like font sizes) is actually depending on remarkably sensible principle: we like to read paragraphs whose letters are about the same subjective size – namely, something like 0.3° tall, from baseline to cap height, in our field of vision.
First, why are we measuring font sizes in degrees? Frankly, it’s the most sensible way to do it when comparing across devices. What else you got – inches? If you talk about trying to make your type half an inch tall, well, great, but half an inch text is crazy big on a phone (one foot from your face), and pretty small on a TV screen (10 feet from your face). The simple truth is: when a font is twice as far away, it needs to be twice as big to compensate.
Now this is great in theory, but in practice, it’s incredibly arduous to calculate:
Not everyone views their phone or monitor from the same distance
Not all devices have the same size pixels
Not all fonts are the same readability – even at the same font size, pixel-density, and viewing distance!
So while you will probably never be calculating this out by hand, I think there are two general lessons that are worth bearing in mind.
The 1/16” Rule
Across a wide variety of viewing distances, you can size your body text according to the following formula:
Font size (in inches) = 1/16" x (the number of feet between the user’s eyeballs and the device)*
*Measuring baseline to cap height, and presuming a fairly readable body font
I don’t expect you to whip out a ruler the next time you make an Android app, but this could come in handy when you take your digital design knowledge to a medium you’ve never worked with: presentation posters, TV apps, slideshows for viewing in an auditorium hall, etc.
The Pixel Density-Viewing Distance Offset
In general, smaller devices have smaller pixels*.
*By “pixel”, I mean not physical pixels, but the concept alternatively referred to as “CSS pixels” (web), “density-indepent pixels” (Android), or “points” (iOS) – in-depth explanation here.
That means smaller devices have more pixels per inch. And that means the same font size appears physically smaller on phones than tablets, and physically smaller on tablets than desktops (and so on for TVs as well, by the way).
That’s not the end of the world, since we hold phones closer to our face. But if the average phone is twice as close to our eyeballs as the average desktop, is the pixel density decrease enough on desktop to make the desktop font twice as big? Short answer: no. Longer answer: as of writing, the typical desktop now has about 33% smaller pixels than your typical mobile device. This means that it’s not stupid to make any desktop text about 33% larger than its mobile equivalent, at least on a page optimized for long form reading.
The sizes are listed as:
iPad Pro, iPad, iPad mini About 44px by 44px
iPhone 6,7,8s, iPhone 6, iPhone SE About 44px by 44px
iPhone 6,7,8s Plus, iPhone 6 Plus About 66px by 66px
The difference is because the iPhone 6,7,8[s] Plus uses the @3x resources while the others use the @2x images. So your @2x and @3x sizes are correct, your @1x image should however be half the size of your @2x image.
Apple and Android dominate the smartphone market, owning over 90 percent of the industry.
To take advantage of this fact, many companies that already have an app based on one platform look to make it work across both Apple and Android devices. But this isn't as easy as it sounds, and taking shortcuts to do so can have serious consequences.
Identify the SD Card - Flashing an SD card is quite straight forward with Mac OS X. Start by pressing CMD SPACE to reveal the Spotlight search bar at the top right hand side of the screen. In this search bar, type terminal and press return to launch the Terminal application.
It’s easy to understand the difference between font-size units when you see them in action. Generally, 1em = 12pt = 16px = 100%. When using these font-sizes, let’s see what happens when you increase the base font size (using the body CSS selector) from 100% to 120%.