Few changes in Swift Code (#191)

* Replaced the confusing construction

* The algorithm works faster than the previous version

02_selection_sort/swift/01_selection_sort.swift

@@ -4,13 +4,9 @@ import Foundation
 func findSmallestIndex <T: Comparable> (_ arr: [T]) -> Int {
     // Stores the smallest value
     var smallest = arr[0]
-    // We don't need any calculation if the array length is 1
-    if arr.count == 1 {
-        return 0
-    }
     // Stores the index of the smallest value
     var smallestIndex = 0
-    for i in 1...arr.count-1 {
+    for i in 1..<arr.count {
         if arr[i] < smallest {
             smallest = arr[i]
             smallestIndex = i
@@ -21,14 +17,17 @@ func findSmallestIndex <T: Comparable> (_ arr: [T]) -> Int {
 
 // Sort array
 func selectionSort <T: Comparable> (arr: [T]) -> [T] {
+    // We don't need any calculation if the array length is 1
+    guard arr.count > 1 else { return arr }
+    
     var newArr: [T] = []
+    
     // We have to make mutableArray reference copy of original array, because Swift 3 doesn't allow to get var parameter
     var mutableArr = arr
-    for _ in 0...mutableArr.count-1 {
+    for _ in 0..<mutableArr.count {
        //Finds the smallest element in the array and adds it to the new array
         let smallestIndex = findSmallestIndex(mutableArr)
-        newArr.append(mutableArr[smallestIndex])
-        mutableArr.remove(at: smallestIndex)
+        newArr.append(mutableArr.remove(at: smallestIndex))
     }
     return newArr
 }