Swift inline conditional?

Question

How do I do this in Swift ?

(someboolexpression ? "Return value 1" : "Return value 2")

(no I have not read the whole manual yet... I probably missed it on page 2!)

OK so its on page 91 and the above appears to be correct. However I am trying to use this in a string like so:

println(" some string \(some expression ? "Return value 1" : "Return value 2")"

but the compiler is not happy. Any idea if this if possible?

This is as close as I have been able to get

let exists = "exists"
let doesnotexist= "does not exist"

println("  something \(fileExists ? exists : doesnotexist)")

It's probably an oversight in the grammar, and you might want to file a bug on it. I haven't checked the grammar for this, but it could be worth noting that it doesn't like escaped literals, only variables. Ie. you cannot do this: println("hello \\("world")"), but you can do this: let world = "world"; println("hello \\(world)"), as you noted. Summed up, it seems to want a variable and not an expression. — Chris Conover, Oct 04 '14 at 05:37
I'll do that, cheers. In the meantime I'll accept @MikeS answer as the best option for now — Duncan Groenewald, Oct 04 '14 at 12:52
you need a space after `let doesnotexist` or an preprocessor error will occur and make sure you have declared `let fileExists: Bool` some where before the `println` statement which should actually be `print` as of Swift 2.0. Otherwise I tried your code it works just fine — rolling_codes, Aug 13 '16 at 15:42

score 155 · Accepted Answer · answered Oct 04 '14 at 04:31

155

If you're looking for a one-liner to do that, you can pull the ?: operation out of the string interpolation and concatenate with + instead:

let fileExists = false // for example
println("something " + (fileExists ? "exists" : "does not exist"))

Outputs:

something does not exist

answered Oct 04 '14 at 04:31

Mike S

41,895
11
89
84

why is this not compiling to me? ` let answer = (enterName_text == nil)? "" : enterName_text.text! ` – Elad Benda Feb 13 '16 at 10:55
@EladBenda this would be better not as a comment, but as a separate question with details on what enterName_text is and the error you're getting. Best guess though is that you really want: if let answer = enterName_text?.text { ... } – Mike S Feb 13 '16 at 16:15
1

When I first tried this ternary operator, I thought it did not work in Swift. Looked here and found this answer. The problem (coming from a C/C++ background) was not putting a space between the '?' and the first argument. The '?' is treated specially in Swift for optional values and the space character makes it clear that it is really a ternary operator. – Jeff Muir May 04 '17 at 01:24

score 32 · Answer 2 · edited Sep 11 '19 at 15:36

32

You can use the new Nil-Coalescing Operator, introduced in Swift 3. It will return default value if someOptional is nil.

let someValue = someOptional ?? ""

Here, if someOptional is nil, this operator will assign "" to someValue.

edited Sep 11 '19 at 15:36

Shemetz

109
1
9

answered Dec 14 '16 at 21:03

Vitalii Gozhenko

9,220
2
48
66

This is such a swifty answer! Exactly what I was looking for. – dustinrwh Nov 07 '17 at 18:36

score 21 · Answer 3 · answered Mar 16 '15 at 16:14

21

var firstBool = true
var secondBool: Bool

firstBool == true ? (secondBool = true) : (secondBool = false)

If in this case, it changes the secondBool to whatever the firstBool is. You can do this with integers and strings too

answered Mar 16 '15 at 16:14

Esqarrouth

38,543
21
161
168

score 11 · Answer 4 · answered Mar 18 '17 at 17:46

It is called a "ternary operator".

With regards to @Esqarrouth's answer, I think a better format would be:

Swift 3:

var firstBool = true
var secondBool: Bool

secondBool = firstBool ? true : false

This is the same as:

var firstBool = true
var secondBool: Bool

if (firstBool == true) {
    secondBool = true
} else {
    secondBool = false
}

score 9 · Answer 5 · answered Sep 26 '17 at 03:25

9

simple solution i used in my projects

Swift 3+

var retunString = (state == "OFF") ? "securityOn" : "securityOff"

answered Sep 26 '17 at 03:25

Sathya Baman

3,424
7
44
77

score 7 · Answer 6 · edited Sep 01 '16 at 04:45

7

You were oh so close. Just needed to assign it to a variable:

self.automaticOption = (automaticOptionOfCar ? "Automatic" : "Manual")

Edit:

Any idea why that same expression can't be embedded in a string?

You can do that:

let a = true
let b = 1
let c = 2

println("\(a ? 1: 2)")

edited Sep 01 '16 at 04:45

Félix Saparelli

8,424
6
52
67

answered Oct 04 '14 at 03:51

Steve Rosenberg

19,348
7
46
53

Any idea why that same expression can't be embedded in a string? – Duncan Groenewald Oct 04 '14 at 03:56
Mmm but this does not work `println("something \(automaticOptionOfCar ? "Automatic" : "Manual")")` ? – Duncan Groenewald Oct 04 '14 at 04:05

Tanmay Bakshi · Answer 7 · 2014-12-26T02:48:51.483

6

Well,

If you concatenate the conditional with the string using the + operator, it should work.

Therefore, Mike is correct.

var str = "Something = " + (1 == 1 ? "Yes" : "No")

edited Dec 26 '14 at 02:48

answered Dec 16 '14 at 04:29

Tanmay Bakshi

61
1
2

score 5 · Answer 8 · answered Nov 28 '17 at 22:35

I have use inline conditional like this :

isFavorite function returns a Boolen

favoriteButton.tintColor = CoreDataManager.sharedInstance.isFavorite(placeId: place.id, type: 0) ? UIColor.white : UIColor.clear

tourOperatorsButton.isHidden = place.operators.count != 0 ? true : false

score 1 · Answer 9 · answered Jun 25 '21 at 09:21

1

For Multiple Condition this can work like this

 let dataSavingTime: DataSavingTime = value == "0" ? .ThirtySecs : value == "1" ? .Timing1 : .Timing2

answered Jun 25 '21 at 09:21

Lalit Pratap

119
1
11

score -1 · Answer 10 · answered Oct 28 '22 at 13:34

-1

One line condition without if and ternary operator

let value = "any"
// set newValue as true when value is "any"
let newValue = value == "any"
print(newValue)
//answer: true

answered Oct 28 '22 at 13:34

Hariharan Sivakumar

82
4

Swift inline conditional?

10 Answers10

Edit: