How do I pass more parameters to a UIAlertAction's handler?

The easiest way is to just pass a closure to the UIAlertAction constructor:

func someFunc(){    //some stuff...    let listINeed = [ "myString" ]    let alert = UIAlertController(title: "Are you sure?", message: "message", preferredStyle: UIAlertControllerStyle.Alert)    alert.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: nil))    alert.addAction(UIAlertAction(title: "Confirm", style: .Destructive, handler:{ action in        // whatever else you need to do here        print(listINeed)    }))    presentViewController(alert, animated: true, completion: nil)}

If you really want to isolate the functional part of the routine, you can always just put:

handleConfirmPressedAction(action:action, needed:listINeed)

into the callback block

A slightly more obscure syntax, that would retain the feel of a function both in passing it to the completion routine and in the callback function itself would be to define handleConfirmPressed as a curried function:

func handleConfirmPressed(listINeed:[String])(alertAction:UIAlertAction) -> (){    print("listINeed: \(listINeed)")}

and then you can addAction using:

alert.addAction(UIAlertAction(title: "Confirm", style: .Destructive, handler: handleConfirmPressed(listINeed)))

Note that the curried function is shorthand for:

func handleConfirmPressed(listINeed:[String]) -> (alertAction:UIAlertAction) -> () {    return { alertAction in        print("listINeed: \(listINeed)")    }}