Why is 'self' used outside of a class?

Question

I'm following this tutorial on GitHub on how to implement SwiftyDropbox in an iOS app. There's a point where it tells me to add this code to my ViewController

import UIKit
import SwiftyDropbox

func myButtonInControllerPressed()
{
    DropboxClientsManager.authorizeFromController(UIApplication.shared, controller: self, openURL: { (url: URL) -> Void in UIApplication.shared.openURL(url)})
}

I then get an error saying

Use of unresolved identifier 'self'

Presumably this is because I'm declaring a function outside of a class. What am I doing wrong? Does anyone know of a tutorial/sample-app that actually works and is up to date with the latest Swift and Xcode that could teach me how to use SwiftyDropbox?

Answer 1

The paragraph before that snippet does say

You can commence the auth flow by calling authorizeFromController:controller:openURL:browserAuth method in your application's view controller.

So it is telling you to write that snippet INSIDE your View Controller (where using self makes sense).

Here's an example

class Controller: UIViewController {

    func myButtonInControllerPressed() {
        DropboxClientsManager.authorizeFromController(UIApplication.shared,
                                                      controller: self,
                                                      openURL: { (url: URL) -> Void in
                                                        UIApplication.shared.openURL(url)
        })
    }

}