Check if optional array is empty in Swift

Question

I realize there are a ton of questions on SO with answers about this but for some reason, I can't get any to work. All I want to do is test if an array has at least one member. For some reason, Apple has made this complicated in Swift, unlike Objective-C where you just tested if count>=1. The code crashes when the array is empty.

Here is my code:

let quotearray = myquotations?.quotations

if (quotearray?.isEmpty == false) {

let item = quotearray[ Int(arc4random_uniform( UInt32(quotearray.count))) ] //ERROR HERE

}

However, I get an error:

Value of optional type '[myChatVC.Quotation]?' must be unwrapped to refer to member 'subscript' of wrapped base type '[myChatVC.Quotation]'.

Neither of the fix-it options to chain or force unwrap solve the error. I have also tried:

if array != nil && array!. count > 0  and if let thearray = quotearray

but neither of those will work either

Thanks for any suggestions.

matt · Accepted Answer · 2020-06-16 19:05:32Z

3

randomElement already exists, so don't reinvent the wheel:

var pepBoys: [String]? = ["manny", "moe", "jack"]
// ... imagine pepBoys might get set to nil or an empty array here ...
if let randomPepBoy = pepBoys?.randomElement() {
    print(randomPepBoy)
}

The if let will fail safely if pepBoys is nil or empty.

answered Jun 16, 2020 at 19:05

matt

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1 Comment

zztop Over a year ago

This code worked as well. Marking it correct as this version is slightly shorter than @Frankenstein's which also worked.

Frankenstein · Accepted Answer · 2020-06-16 19:19:07Z

0

You could unwrap the optional array and use that like this, also use the new Int.random(in:) syntax for generating random Ints:

if let unwrappedArray = quotearray,
    !unwrappedArray.isEmpty {
    let item = unwrappedArray[Int.random(in: 0..<unwrappedArray.count)]
}

edited Jun 16, 2020 at 19:19

answered Jun 16, 2020 at 19:02

Frankenstein

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2 Comments

zztop Over a year ago

Using if let and isEmpty together looks like a good way to test for an optional array having an element

Frankenstein Over a year ago

There is always room for improvement. Just like making the bool check shorter as I just did with unwrappedArray.isEmpty == false statement or calling randomElement on array directly.

yoodu · Accepted Answer · 2021-05-27 02:15:59Z

0

check the first element is exist or not

var arr: [Int]? = [1, 2, 3, 4]
if let el = arr?.first{
  print(el)
}

answered May 27, 2021 at 2:15

yoodu

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Comments

Yehor Chernenko · Accepted Answer · 2021-06-01 14:30:11Z

0

I would recommend use guard statement

guard let array = optionalArray, !array.isEmpty else { return }

edited Jun 1, 2021 at 14:30

answered Jun 16, 2020 at 19:16

Yehor Chernenko

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