I have recently started learning Swift and the Xcode documentation. Nonetheless, I am facing quite some problems with the handlers in general as seen in the code below:
let deleteAction = UIContextualAction(style: .destructive, title: "Delete") { (action, sourceView, completionHandler) in
// Delete the row from the data source
self.restaurantNames.remove(at: indexPath.row)
self.restaurantLocations.remove(at: indexPath.row)
self.restaurantTypes.remove(at: indexPath.row)
self.restaurantIsVisited.remove(at: indexPath.row)
self.restaurantImages.remove(at: indexPath.row)
self.tableView.deleteRows(at: [indexPath], with: .fade)
// Call completion handler with true to indicate
completionHandler(true)
}
I don't quite understand why did the tutorial that I am following (which is appcoda) has written (action, sourceView, completionHandler). For better understanding I tried changing this tuple to (action, sourceView, completionHandler) and it yielded the same result, which surprised me a lot. Therefore I wanted to ask you, what should I put inside these tuples and what is there purpose?
These are the parameters for your closure that you get when the completionHandler is called. This is what they are:
action:
The object containing information about the selected action.
sourceView:
The view in which the action was displayed.
completionHandler:
The handler block for you to execute after you have performed the action. This block has no return value and takes the following parameter: actionPerformed A Boolean value indicating whether you performed the action. Specify true if you performed the action or false if you were unable to perform the action for some reason.