Check if array contains element in Swift 4

Question

I am trying to check if array categories contain number 1 as Int since categories = [Int]() for example categories = {1, 2, 3, 4, 5}

I have tried the below code which gives me error Binary operator '==' cannot be applied to operands of type 'Any' and 'Int'

if categories.contains (where: {$0 == 1}) {
    // 1 is found
}

also tried it without the where and brackets as below which gives me the same error

if categories.contains { $0 == 1 } {
    // 1 is found
}

I tried using just the element as below which gives me error Missing argument label 'where:' in call

if categories.contains(1) {
    // 1 is found
}

How can I do that?

How did you declare the categories array?

Mateen Kajabadi
– Mateen Kajabadi

2018-02-02 04:22:52 +00:00
Commented Feb 2, 2018 at 4:22 — Mateen Kajabadi
– Mateen Kajabadi, Commented Feb 2, 2018 at 4:22
Your categories declaration it is not a valid syntax

Leo Dabus
– Leo Dabus

2018-02-02 04:22:56 +00:00
Commented Feb 2, 2018 at 4:22 — Leo Dabus
– Leo Dabus, Commented Feb 2, 2018 at 4:22

Malik · Accepted Answer · 2018-02-02 04:43:51Z

6

It seems like your category array is of type Any

Ways to fix it

You can declare your array as an Int array
```
var categories: [Int]
```
OR
You can change the following piece of code
```
if categories.contains { $0 == 1 } {
    // 1 is found
}
```
to
```
if categories.contains { ($0 as! Int) == 1 } {
    // 1 is found
}
```
Note: This method might cause your app to crash if your category array has an element other than of type Int

answered Feb 2, 2018 at 4:43

Malik

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2 Comments

Mohamed Ezzat Over a year ago

What is the meaning of "$0" ? @Malik

Malik Over a year ago

@MohamedEzzat $0 is the first parameter passed into a closure. In this instance, when the categories array is traversed with an contains check, $0 holds the value in each iteration

iOS Geek · Accepted Answer · 2018-02-02 04:24:31Z

3

it is working See my output in PlayGround

Code used:

var categories : [Int] = [0,1,2,3,4,5,6,7,8,9]

if categories.contains(5)
{
    print("Yes it contains")
}
else
{
    print("it do not")
}

and also This condition is working

if categories.contains (where: {$0 == 1}) {
    print("yes")
}

see your Array Declaration I think there is main Issue

Declaration 1 :

var categories = [Int]()
categories = [0,1,2,3,4,5,6,7,8,9]

Declaration 2 :

var categories : [Int] = [0,1,2,3,4,5,6,7,8,9]

answered Feb 2, 2018 at 4:24

iOS Geek

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2 Comments

Malik Over a year ago

iOS Geek did mention to check the array declaration. The OP stated in the first line that the array is an Int array. I realise that the error states otherwise which tells me that the OP might have declared the array wrongly (exactly like iOS Geek stated). He is not assuming anything my friend.

iOS Geek Over a year ago

Yes, @Malik, You are right I had mentioned to check the array declaration For that

TheTiger · Accepted Answer · 2018-02-02 07:40:52Z

Regarding error message Binary operator '==' cannot be applied to operands of type 'Any' and 'Int'

Your array is not an Int array instead it contains Any so it needs typecasting before comparision. Declaration of array is also wrong use [] instead of {}. And typecast object as an int ($0 as! Int) == 1 (I'm using force casting here because I know its an Int array).

There are many ways to check if array contains any element.

1> Just try to get the index of element with guard if index is nil means array doesn't contain the element. Although you didn't declare array in right way still I'm considering it a valid array.

let categories: [Int] = [1, 2, 3, 4, 5]
guard categories.index(of: 1) != nil else {
    print("Doesn't Contain")
    return
}
print("Contains")

2> Use contains method

if (categories.contains(1)) {
    print("Contains")
}
else {
    print("Doesn't Contain")
}

3> Not Recommended for this case But still you can get this

let result = categories.filter({$0 == 1})
if result.count == 0 {
   print("Doesn't Contain")
}
else {
   print("Contains")
}

filter returns an array of element which matches with condition. So that if there are multiple 1 in array so it will give you an array of all elements. And $0 describes the object while enumerating the array.

4> Not Recommended for this case

let contains = categories.contains(where: {$0 == 1})
if contains {
    print("Contains")
}
else {
   print("Doesn't Contain")
}

Jumana Alhaddad · Accepted Answer · 2018-02-02 04:53:37Z

0

Thanks to your comments made me check the declaration of the array and the problem was that was declared as [Any] after I get it's value from the UserDefaults. I have checked and found the solution on How do I save an Int array in Swift using NSUserDefaults?

// old declaration
let categories = userDefaults.array(forKey:"categories") ?? [Int]()

// new correct declaration
var categories = [Int]()
if let temp = userDefaults.array(forKey:"categories") as? [Int] {
    categories = temp
}

answered Feb 2, 2018 at 4:53

Jumana Alhaddad

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1 Comment

TheTiger Over a year ago

You didn't mention that you are getting your array from UserDefaults. If you mention first line of your code you will get the answer sooner.

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