Swift update value inside Dictionary<String, Any> in an Array - swift

Question

I have an array of Dictionaries, like so
var myArray: [Dictionary<String, Any>] = [Dictionary<String, Any>]()
Somewhere in my class i add values there, like so:
var myDict = Dictionary<String, Any>()
myDict["Id"] = "someUniqueId"
myDict["v1"] = -42
self.myArray.append(myDict)
Then later i try to update the v1 inside this dict like so:
self.myArray.first(where: { $0["Id"] == "someUniqueId" })?["v1"] = -56
However, the compiler tells me:
Cannot assign through subscript: function call returns immutable value
Any way i can modify the value in array outside of copying the whole dictionary, removing it from array, and re-inserting?
UPDATE This dictionary is not strongly typed because what is inside the dictionary, both types and fieldnames, are controlled by the user in an external system. E.g. we download some metadata and then render controls for this dynamic data.

Answer 1

This is because Swift Dictionary is a value type.
Use a custom class or you can use NSMutableDictionary for this purpose (because NSDictionary is immutable).
var myArray = [NSMutableDictionary]()
var myDict = NSMutableDictionary()
myDict["Id"] = "someUniqueId"
myDict["v1"] = -42
myArray.append(myDict)
myArray.first(where: { $0["Id"] as? String == "someUniqueId" })?["v1"] = -56
print(myArray)
// [{
// Id = someUniqueId;
// v1 = "-56";
// }]

Answer 2

You can make it easier for yourself by wrapping your dictionary in a simple class
class Config {
private var dict: [String: Any]
init(_ dict: [String: Any]) {
self.dict = dict
}
func valueFor(_ key: String) -> Any? {
return dict[key]
}
func setValue(_ value: Any, forKey key: String) {
dict[key] = value
}
}
and use that in your array
var myArray = [Config]()
And use it like this
array.filter { $0.valueFor("Id") as? String == "someUniqueId" }
.first?.setValue(-56, forKey: "v1")
That way you can avoid using classes like NSMutableDictionary and keeping it more pure Swift. Another advantage with a custom class is that you can add functionality to it to simplify your code using it, so for instance if you will be looking up dictionaries by "Id" a lot we can add a computed property for it
var id: String? {
return valueFor("Id") as? String
}
and then the example above would become
array.filter { $0.id == "someUniqueId" }.first?.setValue(-56, forKey: "v1")