Affordance is the quality or property of an object that defines its possible uses or makes clear how it can or should be used.

1. Using Affordance
for Clearer
Source Code

5. Affordance
The quality or property of an object that defines its possible
uses or makes clear how it can or should be used.

6. Showing Action
⠀
var array = [2, 2, 6]
array.remove(2)
⠀
var array = [2, 2, 6]
array.remove(at: 2) // [2, 2]
array.remove(value: 2) // [6]

7. Showing Parameter Usage
⠀
var post = Post()
post.add(string: textField.text)
⠀
var post = Post()
post.add(commentText: textField.text)

8. Grammatical Correctness Helps
⠀
let posts = db.posts(author: currentUser)
⠀
let posts = db.posts(authoredBy: currentUser)

9. Grammatical Correctness Helps
(Except in Initializers)
⠀
let post = Post(authoredBy: currentUser, withText: textView.text)
⠀
let post = Post(author: currentUser, text: textView.text)

10. Good affordances strike a balance
between assuming too much
and assuming too little.

11. Side Effects
let distance = x.distance(to: y)
let success = x.move(toDistanceOf: 3, from: y)
let success = x.set(distanceFrom: y equals: 3)

12. Past Participle
The noun form of a verb
⠀
array.sort()
array.append(item)
let sortedArray = array.sorted()
let completeArray = array.appending(item)

13. More Examples?
isHidden
hasBackButton
past participle UIImage(named: String) already exists
should future of is
clearsSelectionOnViewDidAppear

14. For next month...
uses for completion closures
doSomething(thenDoThis: (ResultType) -> Void) {
queue.async {
let result = expensiveOperation()
mainQueue.async {
thenDoThis(result)
}
}
}
web or file system request
arbitrary event handling
did set event handler
workflow result