７つの数字が入った配列を作り、１ずつ引く

var arr = [9, 8, 7, 6, 5, 4, 3, 2]

var i = 0

while i < arr.count {
    
    arr[i] = arr[i] - 1
    
    i++

}

print(arr) => "[8, 7, 6, 5, 4, 3, 2, 1]\n"