CODEWITHSUNDEEP
iosarraysswiftswift3
Kamlesh Shingarakhiya
Kamlesh Shingarakhiya

Reputation: 2777

Removing object from array in Swift 3

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'

Upvotes: 110

Views: 135124

Answers (13)

yoAlex5
yoAlex5

Reputation: 34175

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") }

Read more here

Upvotes: 4

vadian
vadian

Reputation: 285069

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"}

Upvotes: 202

Andrew Kingdom
Andrew Kingdom

Reputation: 403

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.)

Upvotes: 0

Mohsenasm
Mohsenasm

Reputation: 3141

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")

Upvotes: 15

Renetik
Renetik

Reputation: 6373

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
    }
}

Upvotes: 1

Mahesh Cheliya
Mahesh Cheliya

Reputation: 1364

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

Upvotes: 1

Tj3n
Tj3n

Reputation: 9923

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

  2. 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)
}

Upvotes: 6

Serhii Didanov
Serhii Didanov

Reputation: 2338

Swift 4

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

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

Upvotes: 5

Mark Semsel
Mark Semsel

Reputation: 7155

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)
}

Upvotes: 26

nyxee
nyxee

Reputation: 2811

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

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

Upvotes: 74

Luca Davanzo
Luca Davanzo

Reputation: 21520

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)

Upvotes: 17

Joerg
Joerg

Reputation: 41

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)
}

Upvotes: 4

Dileep
Dileep

Reputation: 2425

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

Upvotes: 1

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