Q:

How do I sort an array of objects in reverse order efficiently? 

Suppose I have an array of dictionaries:
[ { "id": 2 }, { "id": 59 }, { "id": 31 } ... ]

How can I sort this so that it's in descending order, sorted by "id"? 
My initial approach is something like:
Loop through each element, find the biggest one, and put it into a new array.  Then, remove that from the element.  Repeat. 

But I know that's wrong and not efficient. 

A:

You can use the sort function in Swift.  Something like this:
let arr = [["id": 2], ["id": 59], ["id": 31]]
let sortedArr = arr.sort { Int($0["id"]!)  > Int($1["id"]!) }