Метод делегата не срабатывает

Question

У меня есть протокол & делегат, чтобы взять данные JSON и передать его обратно в предыдущий контроллер просмотра в некоторые поля текстов. Я думал, что это правильно, но метод делегата не стреляет в AddBookViewController. Нет раскадровки, все это делается программно/с перьями.

Любая помощь будет оценена в отношении почему, большое спасибо.

ImportISBNViewController

import UIKit 

protocol BookInfoReceived { 
    func sendBookInfo(author: String, title: String) 
} 

class ImportISBNViewController: UIViewController { 

    var session: NSURLSession! 
    var lookUpID:String = "" //0586057242 
    var a: String = "" 
    var t: String = "" 
    var delegate: BookInfoReceived? 

    @IBOutlet weak var isbnNumber: UITextField! 

    init() { 
     super.init(nibName:"ImportISBNViewController", bundle: nil) 
     let config = NSURLSessionConfiguration.defaultSessionConfiguration() 
     session = NSURLSession(configuration: config, delegate: nil, delegateQueue: nil) 
    } 

    required init (coder aDecoder: NSCoder) { 
     super.init(coder: aDecoder) 

    } 

    func importISBN(sender: AnyObject) { 

     lookUpID = isbnNumber.text! 
     println("Pressed Import. ISBN: \(lookUpID)") 
     fetchItem() 
    } 

    func fetchItem() { 

     let requestURL = ("https://openlibrary.org/api/books?bibkeys=" + lookUpID + "&f&jscmd=data&format=json") 
     if let url = NSURL(string: requestURL) { 
      let req = NSURLRequest(URL: url) 

      let dataTask = session.dataTaskWithRequest(req) { 
       (data, response, error) in 
       if data != nil { 
        var error: NSError? 
        if let jsonObject = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &error) as? NSDictionary { 

         println("JSON Found: \(jsonObject.count)") 

         if jsonObject.count == 0 { 
          println("JSON URL has no data.") 
          //COMPUTER SAYS NO 
          self.showAlert() 

         } else { 

          if let bookInfoDictionary: AnyObject = jsonObject["\(self.lookUpID)"]{ 

           //Retrieve the author name. 
           var names = [String]() 
           if let authors = bookInfoDictionary["authors"] as? NSArray { 
            for author in authors { 
             if let author = author as? NSDictionary, 
              let name = author["name"] as? String { 
               names.append(name) 
             } 
            } 
           } 

           self.a = join(",", names) 
           self.t = (bookInfoDictionary["title"] as? String)! 
           println("JSON Done. Title: \(self.t) Author: \(self.a) ") 

           self.delegate?.sendBookInfo(self.a, title: self.t) 
           self.dismissViewControllerAnimated(true, completion: nil) 


          } 

         } 
        } else { 
         if let error = error { 
          println("Error parsing JSON: \(error)") 
         } 
        } 
       } else { 
        println("Error fetching Item: \(error.localizedDescription)") 
       } 
      } 
      dataTask.resume() 
     } 

    } 
func showAlert() { 
     let alert = UIAlertController(title: "ISBN not found", message: "The ISBN entered was not found, would you like to try another?", preferredStyle: .Alert) 

     let okAction = UIAlertAction(title: "OK", style: .Default) { 
      UIAlertAction in 
      println("ALERT: OK Pressed") 
      self.isbnNumber.text = "" 
     } 

     let cancelAction = UIAlertAction(title: "Cancel", style: .Default) { 
      UIAlertAction in 
      println("ALERT: Cancel Pressed") 
      self.dismissImport(self) 
     } 

     NSOperationQueue.mainQueue().addOperationWithBlock { 
      alert.addAction(okAction) 
      alert.addAction(cancelAction) 
      self.presentViewController(alert, animated: true, completion: nil) 
     } 
    } 


func dismissImport(sender: AnyObject) { 
     self.dismissViewControllerAnimated(true, completion: nil) 
    } 

@IBAction func lookUpBook(sender: UIButton) { 
     importISBN(self) 
    } 

@IBAction func cancelImport(sender: AnyObject) { 
    dismissImport(self) 
    } 
} 

AddBookViewController

import UIKit 

class AddBookViewController: UIViewController, BookInfoReceived { 

    @IBOutlet weak var bookTitle: UITextField! 
    @IBOutlet weak var bookAuthor: UITextField! 

    let bookStore: BookStore 

    init (bookStore: BookStore) { 
     self.bookStore = bookStore 
     super.init(nibName: "AddBookViewController", bundle: nil) 

     navigationItem.title = "Add New Book" 

    } 

    required init(coder aDecoder: NSCoder) { 
     fatalError("init(coder:) has not been implemented") 
    } 

    func sendBookInfo(author: String, title: String) { 
     println("HELLO IT'S ME THE DELEGATE") 
     bookTitle.text = title 
     bookAuthor.text = author 
    } 

    @IBAction func importISBN(sender: UIButton) { 

     let importVC = ImportISBNViewController() 
     navigationController!.presentViewController(importVC, animated: true, completion: nil) 
     } 

    @IBAction func saveNewBook(sender: UIButton) { 

     let author = self.bookAuthor.text! 
     let title = self.bookTitle.text! 
     println("Adding book: Author: \(author) Title: \(title)") 

     bookStore.addBook(author, bookTitle: title) 
     println("Book count: \(self.bookStore.allBooks.count)") 
     } 

} 

Answer 1

Делегат не стреляя на любом экземпляре AddBookViewController, потому что вы никогда не устанавливать какой-либо экземпляр AddBookViewController в качестве делегата! Ваш ImportISBNViewController имеет no делегат - так что ничего не происходит.

Answer 2

линия для установки делегата отсутствует

@IBAction func importISBN(sender: UIButton) { 

    let importVC = ImportISBNViewController() 
    importVC.delegate = self 
    navigationController!.presentViewController(importVC, animated: true, completion: nil) 
    }