How to append elements into a dictionary in Swift?

Question

I have a simple Dictionary which is defined like:

var dict : NSDictionary = [ 1 : \"abc\", 2 : \"cde\"]

Now I want to add an element into t

Answer 1

Swift 3+

Example to assign new values to Dictionary. You need to declare it as NSMutableDictionary:

var myDictionary: NSMutableDictionary = [:]
let newValue = 1
myDictionary["newKey"] = newValue
print(myDictionary)

Answer 2

As of Swift 5, the following code collection works.

 // main dict to start with
 var myDict : Dictionary = [ 1 : "abc", 2 : "cde"]

 // dict(s) to be added to main dict
 let myDictToMergeWith : Dictionary = [ 5 : "l m n"]
 let myDictUpdated : Dictionary = [ 5 : "lmn"]
 let myDictToBeMapped : Dictionary = [ 6 : "opq"]

 myDict[3]="fgh"
 myDict.updateValue("ijk", forKey: 4)

 myDict.merge(myDictToMergeWith){(current, _) in current}
 print(myDict)

 myDict.merge(myDictUpdated){(_, new) in new}
 print(myDict)

 myDictToBeMapped.map {
     myDict[$0.0] = $0.1
 }
 print(myDict)

Answer 3

To add new elements just set:

listParrameters["your parrameter"] = value

Answer 4

[String:Any]

For the fellows using [String:Any] instead of Dictionary below is the extension

extension Dictionary where Key == String, Value == Any {
    
    mutating func append(anotherDict:[String:Any]) {
        for (key, value) in anotherDict {
            self.updateValue(value, forKey: key)
        }
    }
}

Answer 5

Up till now the best way I have found to append data to a dictionary by using one of the higher order functions of Swift i.e. "reduce". Follow below code snippet:

newDictionary = oldDictionary.reduce(*newDictionary*) { r, e in var r = r; r[e.0] = e.1; return r }

@Dharmesh In your case, it will be,

newDictionary = dict.reduce([3 : "efg"]) { r, e in var r = r; r[e.0] = e.1; return r }

Please let me know if you find any issues in using above syntax.

Answer 6

I know this might be coming very late, but it may prove useful to someone. So for appending key value pairs to dictionaries in swift, you can use updateValue(value: , forKey: ) method as follows :

var dict = [ 1 : "abc", 2 : "cde"]
dict.updateValue("efg", forKey: 3)
print(dict)