slang (n.) — a type of language that consists of words and phrases that are regarded as very informal, are more common in speech than writing, and are typically restricted to a particular context or group of people.
The Human Interface Guidelines are the Elements of Style — largely prescriptive, focusing on the rules of usage and form and composition that feel less like style and more like structure.
But I think the key to building a warm interface is an understanding of not just how to appeal to the HIG but to appeal to how your users will attempt to use your interface.
(You must not only build sentences of structural soundness but aural soundness.)
Having used an iPhone for many years, I’ve developed some of these. Swiping to go back (and having a mental model of the navigation stack), pulling to refresh (a universal iOS protocol), sure. What about tapping the tab bar twice to scroll to the top? What about empty state? There’s a wealth of commonality in iOS design that isn’t covered in any particular place or location.
It’s all muscle memory. I don’t think about it when I do it; I think about it when suddenly I cannot.
Some of this is generational:
The microinteractions of Snapchat are alien to me because I don’t use snapchat.
The entire dimension of 3D Touch is largely invisible to me, despite having an iPhone 6S, because it just seems sort of distant.
It’s all ephemeral: when’s the last time you swiped an app up to close it? When’s the last time you shook an app to see if it would do anything?
It’s hard to form any concrete takeaway from this. Trying to assign a rigidity to the interactions and muscle memories defeats the purpose: slang is slang because it grooves and mutates and resists documentation. There is no Elements of The Way You Talked in Early 2016 To Your Friends But Not Necessarily Your Coworkers And Even Then Not All Of Your Friends.
The best you can do, I think, is aim for mindfulness in your designs and to let your users express themselves however they feel most comfortable — and to do both things with an understanding that the slang of 2015 is not the slang of 2016.
(And, of course, to do end-user testing. You can never do enough end-user testing.)