ClosureWithoutSelf.swift

import Foundation
import UIKit

class ListViewController: UIViewController {
    
    var listTitle: (() -> String)?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        listTitle = {
            print("closure executed")
            return "Fiction Books"
        }
    }

}


class DetailViewController: UIViewController {
    var listTitle: (() -> String)?

    override func viewDidLoad() {
        super.viewDidLoad()
        guard let title = listTitle?() else { return }
        self.title = title
    }
}