如何计算Swift中选定的UITableView行。 indexPathForSelectedRow中的可选项

Question

I'm trying to get number of selected rows in my tableView:

self.tableView.setEditing(true, animated: true)

tableView.allowsMultipleSelection = true

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
   updateCount()
}

func tableView(tableView: UITableView, didDeselectRowAtIndexPath indexPath: NSIndexPath) {
    updateCount()
}

func updateCount(){

  let list = tableView.indexPathsForSelectedRows() as [NSIndexPath]

  println(list.count)

Everything works good until something is selected. But when there is no selected row, app crashes with "fatal error: unexpectedly found nil while unwrapping an Optional value". I think it is because selection is nil, but how to write this code with Optionals? I tried many ways but app still crashes when I uncheck all selection.

Answer 1

Yes, you're on the right track. The error is happening because no rows are selected. Use conditional binding like so:

func updateCount(){        
    if let list = tableView.indexPathsForSelectedRows() as? [NSIndexPath] {
        println(list.count)
    }
}

Answer 2

You can simply do

func updateCount(){
   if let list = tableView.indexPathsForSelectedRows {
        print(list.count)
   }
 }