InsertionSort.swift

// Using Playground
func insertionSort(_ numbers: Array<Int>) -> Array<Int>
{ 
  var nums = numbers
  
  if (nums.count <= 1) { return nums }
  
  for i in 1..<nums.count {
      
    for j in (1...i).reversed() {
      if (nums[j] < nums[j - 1]) {
        // do swap
        let temp = nums[j]
        nums[j] = nums[j - 1]
        nums[j - 1] = temp
      }
      else {
        // suppose the array before index j is sorted
        // no need for the next iteration
        break
      }
      
    }
    
  }
  
  return nums
}

let array1 = [5, 4, 3, 2 ,1]
let array2 = [9, 5, 6, 11, 1, 2, 3, 4]

print(insertionSort(array1))
print(insertionSort(array2))