Adding additional items to dictionary - swift

Question

Would like to add John together with Peter in this combination:
var myData0: [String: String] = ["Item": "Milk", "Description": "Milk is white", "DrinksMilk": "Peter"]
myData0["DrinksMilk"] = "John"
println(myData0)
Println gives only John back instead Peter AND John. Is there a way to add John without overwriting Peter?

Answer 1

If you want to keep a string value of dictionary, you can do like that
var myData0: [String: String] = ["Item": "Milk", "Description": "Milk is white", "DrinksMilk": "Peter"]
myData0["DrinksMilk"] = myData0["DrinksMilk"]! + ", John"
println(myData0)
If not, you can change the type of dictionary value to AnyObject like that :
var myData0: [String: AnyObject] = ["Item": "Milk", "Description": "Milk is white", "DrinksMilk": "Peter"]
myData0["DrinksMilk"] = [myData0["DrinksMilk"]!, "John"]
println(myData0)

Answer 2

It appears that you are attempting to encode a data type into a dictionary. A better approach, not knowing anything more about your specific problem, is to define a class for this:
class Drink {
var name:String
var desc:String
var drinkers:[Person]
// ...
func addDrinker (person:Person) {
drinkers.append(person)
}
}
You've declared your dictionary to hold values of type String but, as you describe, now you want the dictionary values to be String or Array. The common type of these type value types is Any (it can be AnyObject if you've imported Foundation; but that is a Swift anomaly). You will then need to 'fight' the type system to coerce the "DrinksMilk" field as a modifiable array and to add "John".
// First extract `"DrinksMilk"` and force it to a mutating array:
var drinkers:[String] = myData0["DrinksMilk"]! as [String]
// Add the new drinker
drinkers.append("John")
// Reassign back into data
myData0["DrinksMilk"] = drinkers