Populating a global dictionary from a loop - swift

Question

I'm trying to loop through some parsed JSON from an API and build a global dictionary that can be accessed throughout the app. I'm getting an error when trying to set the dictionary item.
The global var is set as
var propListArray = [Int : [String : String]] ()
//LOOP THROUGH PROPERTIES
let itemArray = dataDictionary["properties"] as! NSArray //HAVE DATA HERE JUST FINE
var i = 0
for item in itemArray {
let propertyID = item["id"]! as! String
print(propertyID) //THIS PRINTS FINE IN CONSOLE
propListArray[i]!["propertyID"] = propertyID //THIS THROWS AN ERROR ON EXECUTION
i++
}
I want to end up with an array like this
propertyListArray[0]["propertyID"] = "16001"
propertyListArray[1]["propertyID"] = "16001"
propertyListArray[2]["propertyID"] = "16001"
propertyListArray[3]["propertyID"] = "16001"
There will be other vars per item as well such as title, etc. But just trying to get at least the one var in on each item.
Any help would be amazing!! Thank you.

Answer 1

propListArray is empty so trying to get the dictionary at any index will return nil, Then when you try to set a value it will cause the error.
You can fix it by creating the dictionary then assigning it to you global dictionary at the correct index.
var propListArray = [Int : [String : String]] ()
let itemArray = dataDictionary["properties"] as! NSArray
for (index, item) in itemArray.enumerate() { {
let propertyID = item["id"]! as! String
let data = ["propertyID": propertyID]
propListArray[index] = data
}

Answer 2

Quick fix:
var propListArray = [Int : [String : String]] ()
let itemArray = dataDictionary["properties"] as! NSArray
var i = 0
for item in itemArray {
let propertyID = item["id"]! as! String
propListArray[i] = ["propertyID": propertyID]
i++
}
However, i++ within the for loop is not idiomatic Swift. In fact, i++ and C-style for loops are going to be removed in Swift 3. It is better to use enumerate():
var propListArray = [Int : [String : String]] ()
let itemArray = dataDictionary["properties"] as! NSArray
for (i, item) in itemArray.enumerate() {
let propertyID = item["id"]! as! String
propListArray[i] = ["propertyID": propertyID]
}
propListArray[0]?["propertyID"]