Swift - Update Value of a specific item in a nested dictionary - arrays

Question

I have a tableview and each cells are meant to be linked to an array inside a dictionary.
var buttonAction : [String: [ButtonAction]] = [:]
below is the struct of the buttonAction
struct ButtonAction: Codable {
var action: String
var array_linked_of_buttons: [[String:String]]
init(action: String, array_linked_of_buttons: [[String:String]]) {
self.action = action
self.array_linked_of_buttons = array_linked_of_buttons
}
}
It gets a bit complicated to explain the whole code but when I connect two buttons together, I can get the data for the variable "singleAction" which then can be added to the button action dictionary "array_linked_of_buttons".
let singleAction = [linkedButtonUUID: connectorMarker.UUIDpic.uuidString, linkedButtonCategory: "", linkedButtonName: connectorMarker.name]
let mainMarkerAction = mainMarker.buttonAction["button actions array"]!
for existingMarker in mainMarkerAction {
actionArray.append(existingMarker)
}
var actionSub = actionArray[indexRowTag].array_linked_of_buttons
if let addAction = actionSub.filter({$0[linkedButtonUUID] == connectorMarker.UUIDpic.uuidString}).first {
print("MARKER Exists", addAction)
} else {
actionSub.append(singleAction)
print("UPDATED MARKER", actionSub)
}
let action = ButtonAction(action: actionArray[indexRowTag].action, array_linked_of_buttons: actionSub)
//ISSUE--?? mainMarker.buttonAction.updateValue(VALUE forKey: "button actions array")
saveData()
I can workout which item of the dictionary needs to be edited but how do I update that specific value? I am really confused has it just creates a new item but I want to update a previous one.
So for example, I want to append the "array_linked_buttons" of the item 0 and have 4 items instead of 3.
This is how my dictionary looks like if that helps too
I have searched other questioned but I still work it out.
Any help pointing me in the right direction is much appreciated!

Answer 1

Copying instead of changing value happened because you're using struct for ButtonAction which has value semantics and swift create copy on assigning to any variable.
You need to use class instead. Classes have reference semantics, so it won't create new instance on assigning to variable so you'll be able to update property of needed instance.

Answer 2

I worked out i was updating the main dictionary array and not the nested array.
The code below is what I used in the end.
let singleAction = [linkedButtonUUID: connectorMarker.UUIDpic.uuidString, linkedButtonCategory: "", linkedButtonName: connectorMarker.name]
var mainMarkerAction = mainMarker.buttonAction["button actions array"]!
for existingMarker in mainMarkerAction {
actionArray.append(existingMarker)
}
var actionSub = actionArray[indexRowTag].array_linked_of_buttons
if let addAction = actionSub.filter({$0[linkedButtonUUID] == connectorMarker.UUIDpic.uuidString}).first {
print("MARKER HERE", addAction)
} else {
actionArray[indexRowTag].array_linked_of_buttons.append(singleAction)
}
mainMarkerAction[indexRowTag] = actionArray[indexRowTag]