三元条件运算符为零/不为零

Question

I can use the ternary conditional operator for an if {} else {} statement like this: a ? x : y a ? x : y , or question ? answer1 : answer2 question ? answer1 : answer2 .

Is it possible to use this format to check if, instead of whether a is true or false , a == nil or a != nil ?

---

UPDATE: This was arguably the biggest brain fart of my career.

Answer 1

You can do this:

(a == nil) ? x : y

(Parentheses are not required but may make the code clearer.)

You can do this if you want something more confusing:

a.map { _ in x } ?? y

Answer 2

  a != nil ? a! : b

The code above uses the ternary conditional operator and forced unwrapping (a!) to access the value wrapped inside a when a is not nil, and to return b otherwise. The nil coalescing operator provides a more elegant way to encapsulate this conditional checking and unwrapping in a concise and readable form.

example :

let defaultColorName = "red"
var userDefinedColorName: String?   // defaults to nil

var colorNameToUse = userDefinedColorName ?? defaultColorName
// userDefinedColorName is nil, so colorNameToUse is set to the default of "red"

Reference : Apple documentation

Answer 3

You can use ternary operator as long as your statement returns boolean value. Here, a == nil or a != nil returns boolean value so 'Yes' you can use it.