var sr=["brazil","india","nepal","canda","usa"]

// YOUR SOLUTION. WORKS VERY WELL.

var myclosure = { (_ s1: String, _ s2: String) -> Bool in
    return s1 > s2
}
var sort=sr.sorted(by: myclosure)

// BUT JUST TO HELP YOU TO UNDERSTAND THE DIFFERENT WAYS TO WRITE A CLOSURE.
// THE OPERATIONS BELOW ACHIEVE THE EXACT SAME THING.

sr = sr.sorted(by: { return $0 > $1 })
sr = sr.sorted(by: { $0 > $1 })
sr = sr.sorted { $0 > $1 }