How to remove a key-value pair from swift dictionary?

Question

I want to remove a key-value pair from a dictionary like in the example.

var dict: Dictionary<String,String> = [:]
//Assuming dictionary is added some data.
var willRemoveKey = "SomeKey"
dict.removePair(willRemoveKey) //that's what I need

Hautbois

Answer 1

You can use this:

dict[willRemoveKey] = nil

or this:

dict.removeValueForKey(willRemoveKey)

The only difference is that the second one will return the removed value (or nil if it didn't exist)

Swift 3

dict.removeValue(forKey: willRemoveKey)

Mush

this should now be called dict.removeValue(willRemoveKey) since it looks like .removeValueForKey has been renamed - thanks for the help! – Sendoff

So nice and so clean. Love it! – Hyacinthhyacintha

If your values are optionals how can the subscript syntax work? – Hm

Has anyone else noticed that the docs say this is O(n) where n is the size of the dictionary?! – Futrell

@Hm Assigning the subscript to nil always deletes the key. To assign a true nil value in a dictionary with an optional Value type, assign .some(nil). – Aluminate

Answer 2

Swift 5, Swift 4, and Swift 3:

x.removeValue(forKey: "MyUndesiredKey")

Cheers

Whirlybird

Answer 3

dict.removeValue(forKey: willRemoveKey)

Or you can use the subscript syntax:

dict[willRemoveKey] = nil

Littlejohn

Answer 4

var dict: [String: Any] = ["device": "iPhone", "os": "12.0", "model": "iPhone 12 Pro Max"]

if let index = dict.index(forKey: "device") {
   dict.remove(at: index)
}

print(dict) // ["os": "12.0", "model": "iPhone 12 Pro Max"]

Words

Answer 5

For serial removal:

let forbidenParameters = [
            "key1",
            "key2",
            "key3"
        ]       
let cleanParameters = parameters.filter { !forbidenParameters.contains($0.key) }

Sulfapyrazine

Answer 6

let dict = ["k1": "v1" , "k2": "v2"]
  for ( k, _) in dict{
        dict.removeValue(forKey: k)
       }

• Just Loop through it and remove value for key
• removeValue(forKey : k) for value

Detruncate