About "Declaration is only valid at file scope"

Question

I have a class and extension Swift file. After adding a delegate that I declared in another file to the class, Xcode shows this error

Declaration is only valid at file scope

at the extension line. I don't know what the problem is.

Can anyone help me to fix it?

class ListViewController: UIViewController, AddItemViewControllerDelegate {...}

extension ListViewController: UITableViewDataSource{
    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        tableView.deselectRowAtIndexPath(indexPath, animated: true)
        performSegueWithIdentifier("ShowDetail", sender: indexPath)
    }

}

Chrystal

Can you show the code that's producing this error? – Yseulta

@0x7fffffff♦ yes sure – Chrystal

just in case, ensure that your extension is OUTSIDE your class! :) – Indefeasible

The extension must be at the root level - don't embed them into a class or whatever. – Chingchinghai

Answer 1

The error is somewhere in your ... — that error means that your ListViewController class didn't get closed, so the extension is being interpreted as nested inside, like this:

class ListViewController {
    ...
    extension ListViewController {
    }
}

Find the missing closing brace and you should solve the problem.

Deweese

Thanks for replying. I just double checked my code, the class is closed for sure. Or is it the matter of conforming protocol? – Chrystal

Oh, right—perhaps the error message is just bad. That method actually belongs to UITableViewDelegate. If you want to conform to UITableViewDataSource, you need at least tableView:numberOfRowsInSection: and tableView:cellForRowAtIndexPath:. – Deweese

yeap my closing curly brace was in the incorrect position. thanks – Gerthagerti

Answer 2

The extension must be at the root level - don't embed them into a class or whatever.

Chingchinghai

Answer 3

Make sure that the extension is declared at the end of your main class and after the last curly braces "}"

class ListViewController: UIViewController, AddItemViewControllerDelegate {
   //Make sure that everything is clean here! 
}

extension ListViewController: UITableViewDataSource{
    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        tableView.deselectRowAtIndexPath(indexPath, animated: true)
        performSegueWithIdentifier("ShowDetail", sender: indexPath)
    }
}

Neral

Answer 4

Make sure your class and extension are seperated.

class ViewController: UIViewController {}

extension name: type {}

Achromatous

Answer 5

I had my extension calls at the bottom of my file and put them at the top and that fixed it for me. At the bottom, they were outside the class scope so I was a little stumped and just tried this.

Rhapsodist

Answer 6

The extension should be out of the Class.

    class ListViewController: UIViewController, AddItemViewControllerDelegate {...}
    
    // Code...
    
    }
    
    extension ListViewController: UITableViewDataSource{
        func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
            tableView.deselectRowAtIndexPath(indexPath, animated: true)
            performSegueWithIdentifier("ShowDetail", sender: indexPath)
        }

Allene