Swift - "use of unresolved identifier"

Question

I am studying Swift! I want create Main interface on xib. But have error "use of unresolved identifier".

Add code from MainViewController

import Foundation

public class MainViewController : BaseViewController {

    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)

        // TODO: Write your test code here
        // ...
    } }

UPD:(Add image)

Answer 1

1) Right Click your MainViewController.swift

2) Select Show File Inspector

3) On Right side panel, look at Target Membership

4) Add your class to target by check the box :)