Iterate over collection two at a time in Swift

Question

Say I have an array [1, 2, 3, 4, 5]. How can I iterate two at a time?

Iteration 1: (1, 2)
Iteration 2: (3, 4)
Iteration 3: (5, nil)

Answer 1

I personally dislike looping through half the list (mainly because of dividing), so here is how I like to do it:

let array = [1,2,3,4,5];
var i = 0;

while i < array.count {
    var a = array[i];
    var b : Int? = nil;
    if i + 1 < array.count {
        b = array[i+1];
    }
    print("(\(a), \(b))");

    i += 2;
}

You loop through the array by incrementing by 2.

If you want to have nil in the element, you need to use optionals.