Removing object from array in Swift 3

Question

In my application I added one object in array when select cell and unselect and remove object when re-select cell. I used that code but give me error.

extension Array {
    func indexOfObject(object : AnyObject) -> NSInteger {
        return (self as NSArray).indexOfObject(object)
    }

    mutating func removeObject(object : AnyObject) {
        for var index = self.indexOfObject(object); index != NSNotFound; index = self.indexOfObject(object) {
            self.removeAtIndex(index)
        }
    }
}

class MyViewController: UITableViewController {
    var arrContacts: [Any] = []
    var contacts: [Any] = []

    func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
        arrContacts.removeObject(contacts[indexPath.row])
    }
}

It gives me 2 error like that:

C-style for statement has been removed in Swift 3
Value of type '[Any]' has no member 'removeObject'

You can use a Set<Contact> rather than an Array. Can you provide more information about your contact object? If you have made it yourself you will need it to conform to Hashable and Equatable in order to put it in a set — Paulw11
– Paulw11, Commented Nov 29, 2016 at 6:58

vadian · Accepted Answer · 2022-01-27 09:00:40Z

203

The Swift equivalent to NSMutableArray's removeObject is:

var array = ["alpha", "beta", "gamma"]

if let index = array.firstIndex(of: "beta") {
    array.remove(at: index)
}

if the objects are unique. There is no need at all to cast to NSArray and use indexOfObject:

The API index(of: also works but this causes an unnecessary implicit bridge cast to NSArray.

Of course you can write an extension of RangeReplaceableCollection to emulate the function. But due to value semantics you cannot name it removeObject.

extension RangeReplaceableCollection where Element : Equatable {
    @discardableResult
    mutating func remove(_ element : Element) -> Element?
    {
        if let index = firstIndex(of: element) {
            return remove(at: index)
        }
        return nil
    }
}

Like remove(at: it returns the removed item or nil if the array doesn't contain the item.

If there are multiple occurrences of the same object use filter. However in cases like data source arrays where an index is associated with a particular object firstIndex(of is preferable because it's faster than filter.

Update:

In Swift 4.2+ you can remove one or multiple occurrences of beta with removeAll(where:):

array.removeAll{$0 == "beta"}

edited Jan 27, 2022 at 9:00

answered Nov 29, 2016 at 7:40

vadian

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6 Comments

zeeple Over a year ago

This is the best answer, but it is beyond stupid not to have a remove(object: "beta").

Adam Waite Over a year ago

I think .index(of: is only available if the collection contains Equatable types.

vadian Over a year ago

@AdamWaite Yes but this applies also to the Foundation types.

juancazalla Over a year ago

This isn't right, what if you have more than one "beta"? This only works if the array does not contain more than one occurrences. The right answer is using a filter or running this answer in a while, while let index = array.index(of: "beta") { array.remove(at: index) }

vadian Over a year ago

@juancazalla You are right but in the case if the array can contain more than one occurrence use the filter solution. But if the objects are unique use always index(of because it's much more performant than filter

|

nyxee · Accepted Answer · 2017-06-22 13:21:25Z

74

var a = ["one", "two", "three", "four", "five"]

// Remove/filter item with value 'three'
a = a.filter { $0 != "three" }

answered Jun 22, 2017 at 13:21

nyxee

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3 Comments

Michael Over a year ago

That is the correct Swift solution, that makes use of syntax goodies offered by the language.

TomSawyer Over a year ago

What if item is an object?

Mike Taverne Over a year ago

@TomSawyer to filter out an object, use $0 !==

Mark Semsel · Accepted Answer · 2017-08-01 18:36:58Z

26

For Swift 3, you can use index(where:) and include a closure that does the comparison of an object in the array ($0) with whatever you are looking for.

var array = ["alpha", "beta", "gamma"]
if let index = array.index(where: {$0 == "beta"}) {
  array.remove(at: index)
}

answered Aug 1, 2017 at 18:36

Mark Semsel

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1 Comment

Mohamed Irshad Over a year ago

will this work if I want to remove multiple objects? like (where: {$0 == "beta" || $0 == "gamma" })

Luca Davanzo · Accepted Answer · 2017-06-13 10:35:44Z

17

Another nice and useful solution is to create this kind of extension:

extension Array where Element: Equatable {

    @discardableResult mutating func remove(object: Element) -> Bool {
        if let index = index(of: object) {
            self.remove(at: index)
            return true
        }
        return false
    }

    @discardableResult mutating func remove(where predicate: (Array.Iterator.Element) -> Bool) -> Bool {
        if let index = self.index(where: { (element) -> Bool in
            return predicate(element)
        }) {
            self.remove(at: index)
            return true
        }
        return false
    }

}

In this way, if you have your array with custom objects:

let obj1 = MyObject(id: 1)
let obj2 = MyObject(id: 2)
var array: [MyObject] = [obj1, obj2]

array.remove(where: { (obj) -> Bool in
    return obj.id == 1
})
// OR
array.remove(object: obj2)

answered Jun 13, 2017 at 10:35

Luca Davanzo

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2 Comments

juancazalla Over a year ago

This only works if the array does not contain more than one occurrences. The right answer is using a filter or running this answer in a while. As a user of this extension, I expect it to remove all the occurrences and not only one

Radek Wilczak Over a year ago

It's nice, but it should be remove(element: Element) because in Array you can store also types like Int, Double - they are not objects.

Mohsenasm · Accepted Answer · 2020-01-27 13:11:55Z

14

In Swift 5, Use this Extension:

extension Array where Element: Equatable{
    mutating func remove (element: Element) {
        if let i = self.firstIndex(of: element) {
            self.remove(at: i)
        }
    }
}

example:

var array = ["alpha", "beta", "gamma"]
array.remove(element: "beta")

In Swift 3, Use this Extension:

extension Array where Element: Equatable{
    mutating func remove (element: Element) {
        if let i = self.index(of: element) {
            self.remove(at: i)
        }
    }
}

example:

var array = ["alpha", "beta", "gamma"]
array.remove(element: "beta")

edited Jan 27, 2020 at 13:11

answered Oct 14, 2018 at 12:57

Mohsenasm

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Comments

Cœur · Accepted Answer · 2019-02-26 01:51:12Z

6

for var index = self.indexOfObject(object); index != NSNotFound; index = self.indexOfObject(object) is for loop in C-style and has been removed

Change your code to something like this to remove all similar object if it have looped:

let indexes = arrContacts.enumerated().filter { $0.element == contacts[indexPath.row] }.map{ $0.offset }
for index in indexes.reversed() {
   arrContacts.remove(at: index)
}

edited Feb 26, 2019 at 1:51

Cœur

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answered Nov 29, 2016 at 7:50

Tj3n

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1 Comment

Ryan X Over a year ago

enumerated -> filter -> map and remove(at) is smart solution. Recommend this one

Serhii Didanov · Accepted Answer · 2018-08-01 08:03:12Z

5

Swift 4

var students = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]

if let index = students.firstIndex(where: { $0.hasPrefix("A") }) {
   students.remove(at: index)
}

answered Aug 1, 2018 at 8:03

Serhii Didanov

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Comments

yoAlex5 · Accepted Answer · 2023-01-06 08:33:40Z

5

Swift Remove object from array

In Swift 3 and Swift 4

var array = ["a", "b", "c", "d", "e", "f"]

for (index, element) in array.enumerated().reversed() {
    array.remove(at: index)
}

From Swift 4.2 you can use more advanced approach(faster and memory efficient)

array.removeAll(where: { $0 == "c" })

instead of

array = array.filter { !$0.hasPrefix("c") }

Comments

Joerg · Accepted Answer · 2017-06-13 10:23:19Z

4

The correct and working one-line solution for deleting a unique object (named "objectToRemove") from an array of these objects (named "array") in Swift 3 is:

if let index = array.enumerated().filter( { $0.element === objectToRemove }).map({ $0.offset }).first {
   array.remove(at: index)
}

answered Jun 13, 2017 at 10:23

Joerg

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Comments

Dileep · Accepted Answer · 2016-11-29 08:19:17Z

1

Try this in Swift 3

array.remove(at: Index)

Instead of

array.removeAtIndex(index)

Update

"Declaration is only valid at file scope".

Make sure the object is in scope. You can give scope "internal", which is default.

index(of:<Object>) to work, class should conform to Equatable

edited Nov 29, 2016 at 8:19

answered Nov 29, 2016 at 7:26

Dileep

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Comments

Mahesh Cheliya · Accepted Answer · 2019-08-03 11:57:48Z

1

This is official answer to find index of specific object, then you can easily remove any object using that index :

var students = ["Ben", "Ivy", "Jordell", "Maxime"]
if let i = students.firstIndex(of: "Maxime") {
     // students[i] = "Max"
     students.remove(at: i)
}
print(students)
// Prints ["Ben", "Ivy", "Jordell"]

Here is the link: https://developer.apple.com/documentation/swift/array/2994720-firstindex

answered Aug 3, 2019 at 11:57

Mahesh Cheliya

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Comments

Renetik · Accepted Answer · 2020-01-11 16:55:24Z

1

Extension for array to do it easily and allow chaining for Swift 4.2 and up:

public extension Array where Element: Equatable {
    @discardableResult
    public mutating func remove(_ item: Element) -> Array {
        if let index = firstIndex(where: { item == $0 }) {
            remove(at: index)
        }
        return self
    }

    @discardableResult
    public mutating func removeAll(_ item: Element) -> Array {
        removeAll(where: { item == $0 })
        return self
    }
}

edited Jan 11, 2020 at 16:55

answered Mar 14, 2019 at 22:03

Renetik

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2 Comments

jeet.chanchawat Over a year ago

Argument labels '(where:)' do not match any available overloads

Renetik Over a year ago

@jeet.chanchawat well probably different swift version then ... Oh this question was for 3 ? Well I think I had 4.2 at time of writing but don't remember now, will check it later, it definitely worked for me

Andrew Kingdom · Accepted Answer · 2020-08-14 07:18:56Z

This is what I've used (Swift 5)...

    extension Array where Element:Equatable
    {
        @discardableResult
        mutating func removeFirst(_ item:Any ) -> Any? {
            for index in 0..<self.count {
                if(item as? Element == self[index]) {
                    return self.remove(at: index)
                }
            }
            return nil
        }
        @discardableResult
        mutating func removeLast(_ item:Any ) -> Any? {
            var index = self.count-1
            while index >= 0 {
                if(item as? Element == self[index]) {
                    return self.remove(at: index)
                }
                index -= 1
            }
            return nil
        }
    }

    var arrContacts:[String] = ["A","B","D","C","B","D"]
    var contacts: [Any] = ["B","D"]
    print(arrContacts)
    var index = 1
    arrContacts.removeFirst(contacts[index])
    print(arrContacts)
    index = 0
    arrContacts.removeLast(contacts[index])
    print(arrContacts)

Results:

   ["A", "B", "D", "C", "B", "D"]
   ["A", "B", "C", "B", "D"]
   ["A", "B", "C", "D"]

Important: The array from which you remove items must contain Equatable elements (such as objects, strings, number, etc.)

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