Sort an array of optional items that holds yet another optional

Question

How can I sort an array of optionals that holds an optional NSdate?

class HistoryItem {
   var dateCompleted: NSDate?
}

let firstListObject = someListOfObje         


        

Answer 1

Your sort function could use a combination of optional chaining and the nil coalescing operator:

sort(&array) {
    (item1, item2) -> Bool in
    let t1 = item1?.dateCompleted ?? NSDate.distantPast() as! NSDate
    let t2 = item2?.dateCompleted ?? NSDate.distantPast() as! NSDate
    return t1.compare(t2) == NSComparisonResult.OrderedAscending
}

This would sort the items on the dateCompleted value, and all items that are nil and items with dateCompleted == nil are treated as "in the distant past" so that they are ordered before all other items.

---

Update for Swift 3 (assuming that dateCompleted is a Date):

array.sort { (item1, item2) -> Bool in
    let t1 = item1?.dateCompleted ?? Date.distantPast
    let t2 = item2?.dateCompleted ?? Date.distantPast
    return t1 < t2
}

Answer 2

Swift 4. if you want to keep optional values at the end, for example, use Int.max:

self.values.sort { (item1, item2) -> Bool in
    let value1 = item1.seconds ?? Int.max
    let value2 = item2.seconds ?? Int.max
    return value1 < value2
}