Why does passing an unnamed function as transform to array add one to iteration count in playground in furthest abstractions

Question

I'm in the process of getting comfortable passing unnamed functions as arguments and I am using this to practice with, based off of the examples in the Swift Programming Guide.

So we have an array of Ints:

var numbers: Int[] = [1, 2, 3, 4, 5, 6, 7]

And I apply a transform like so: (7)

func transformNumber(number: Int) -> Int {
    let result = number * 3
    return result
}

numbers = numbers.map(transformNumber)

Which is equal to: (7)

numbers = numbers.map({(number: Int) -> Int in
    let result = number * 3
    return result;
    })

Which is equal to: (8)

numbers = numbers.map({number in number * 3})

Which is equal to: (8)

numbers = numbers.map({$0 * 3})

Which is equal to: (8)

numbers = numbers.map() {$0 * 3}

As you can see in the following graphic, the iteration count in the playground sidebar shows that in the furthest abstraction of a function declaration, it has an 8 count.

Question

Why is it showing as 8 iterations for the last two examples?

Answer 1

It's not showing 8 iterations, really. It's showing that 8 things executed on that line. There were 7 executions as part of the map function, and an 8th to do the assignment back into the numbers variable.

It looks like this could probably provide more helpful diagnostics. I would highly encourage you to provide feedback via https://bugreport.apple.com.