Swift Dictionary [String:String] to NSMutableDictionary? - swift

Question

I am trying to create and assign a Swift Dictionary of type [String : String] at the SKSpriteNode property userData which requires an NSMutableDictionary. When I try this I get the error:
'[String : String]' is not convertible to 'NSMutableDictionary'
Can anyone point me in the right direction?
// USER DATA
var dictionary: [String : String] = Dictionary()
dictionary["Orbit"] = orbit
dictionary["Zone"] = zone
dictionary["Impact"] = impact
var foundationDictionary = dictionary as NSMutableDictionary
neoSprite.userData = foundationDictionary

Answer 1

There’s no built-in cast for this. But instead you can use NSMutableDictionary’s initializer that takes a dictionary:
var foundationDictionary = NSMutableDictionary(dictionary: dictionary)

Answer 2

One alternative answer to the answers above is to cast your dictionary to NSDictionary create a mutable copy of it and cast it to NSMutableDictionary. Too complicated, right ? Therefore I recommend creating new NSMutableDictionary from Dictionary this is just an alternative
var foundationDictionary = (dictionary as NSDictionary).mutableCopy() as! NSMutableDictionary

Answer 3

Can you try to replace this line:
var foundationDictionary = dictionary as NSMutableDictionary
With this code:
var foundationDictionary = NSMutableDictionary(dictionary: dictionary)

Answer 4

Dictionaries
Create immutable dictionary
let dictionary = ["Item 1": "description", "Item 2": "description"]
Create mutable dictionary
var dictionary = ["Item 1": "description", "Item 2": "description"]
Append new pair to dictionary
dictionary["Item 3"] = "description"

Answer 5

I know I am so late in answering this question and one answer is already accepted, but still to help someone.
Sometime converting swift dictionary ([String : String] or [AnyHashable : String] or any other) to Objective-C NSMutableDictionary, if there are some nested objects like array or dictionaries within that will not get mutable as so when updating the values will get error of [NSDictionaryI setObject:forKey:]: unrecognised selector sent to instance
To prevent this error one can convert the object in objective-c class.
In my case I am converting a JSON string into swift dictionary and passing it to objective c class by casting it in NSMutableDictionary as per my core requirement. This gives me an above error when I try to update the NSMutableDictionary in Objective C class.
After surfing and trying much I found that if I try to convert my JSON string in NSMutableDictionary in Objective-C class itself than it worked for me.
So try this: In aVC.swift
let Str: String = nsmanagedobject.value(forKey: "<key>") as? String {
if let mutableDict: NSMutableDictionary = ApplicationData.convertJsonObject(fromJsonString: Str) as? NSMutableDictionary {
......
<Your code to pass NSMutableDictionary to respected Objective-C class>
......
}
ApplicationData.h
+ (NSObject *)convertJsonObjectFromJsonString:(NSString *)jsonString;
ApplicationData.m
+ (NSObject *)convertJsonObjectFromJsonString:(NSString *)jsonString {
NSObject *jsonObject = nil;
if ([jsonString length] > 0) {
NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
if (jsonData) {
jsonObject = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:nil];
}
}
NSLog(#"jsonObject: %#",jsonObject);
return jsonObject;
}
I hope this will help someone and save some time.