swift - how to retain the value of the last iteration on a sequence in for-in -

var index: int=0 index in 1...3{     print(index) } print(index)//prints 0 

if run code, last print gives 0, means index inside for-in not same outside. seems force declares new constant.
looking similar way retain last value in sequence

i know can

var index_out: int=0 index in 1...3{     print(index)     index_out = index } print(index_out) 

if you're gonna loop through , want know end index use amount of times looped through it:

let n = 3 index in 1...n{     print(index) } print(n) 

or array:

let array = [int](count: 10, repeatedvalue: 2)  index in 0..<array.count {     print(index) }  print(array.count)