How to stop enumerating attributes of a NSAttributedString?

Question

In the documentation of the enumerateAttribute method it is said, regarding the stop argument of the block, that:

The block

Answer 1

The parameter is a reference that holds the actual value:

let attributed: NSAttributedString = ...

attributed.enumerateAttribute(
    NSFontAttributeName,
    in: NSRange(location: 0, length: attributed.length),
    options: []
) { value, range, stop in
    stop.pointee = true
}

See the reference for UnsafeMutablePointer.