Swift 2.2: Class 'XX' has no initializers

Question

Probably this question have been asked previously, yet i am asking again. Because i couldn't find a solution for my problem. I have a fairly simple class on which i am getting this error. Please take a look at the bellow code.

import UIKit
import QuartzCore


protocol AddItemViewControllerDelegate {
    func addItemViewControllerDidCancel(controller: InsertItemViewController)
    func addItemViewController(controller: InsertItemViewController, didFinishAddingItem item: ChecklistItem)
    func addItemViewController(controller: InsertItemViewController, didFinishEditingItem item: ChecklistItem)
}


class InsertItemViewController: UITableViewController, UITextFieldDelegate, UITextViewDelegate {

    @IBOutlet var notesField: UITextView!

    var notes: String = ""
    var shouldRemind: Bool = false
    var dueDate: NSDate = NSDate()
    var delegate: AddItemViewControllerDelegate
    var itemToEdit: ChecklistItem {
        get {
            return self.itemToEdit
        }
        set(newItem) {
            if itemToEdit != newItem {
                self.itemToEdit = newItem
                notes = itemToEdit.notes
                shouldRemind = itemToEdit.shouldRemind
                dueDate = itemToEdit.dueDate
            }
        }
    }
    @IBOutlet var dueDateLabel: UILabel!
    var activityViewController: UIActivityViewController!


    convenience required init(coder aDecoder: NSCoder) {
        self.init(coder: aDecoder)
        notes = ""
        shouldRemind = true
        dueDate = NSDate()
    }


    @IBAction func cancel() {
        self.delegate.addItemViewControllerDidCancel(self)
    }

    @IBAction func done() {
        if self.itemToEdit == "" {
            let item: ChecklistItem = ChecklistItem()
            item.notes = self.notesField.text!
            item.shouldRemind = true
            item.dueDate = dueDate
            self.delegate.addItemViewController(self, didFinishAddingItem: item)
        }
        else {
            self.itemToEdit.notes = self.notesField.text!
            self.itemToEdit.shouldRemind = true
            self.itemToEdit.dueDate = dueDate
            self.delegate.addItemViewController(self, didFinishEditingItem: self.itemToEdit)
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
            ///wecreate
        let doneButton: UIBarButtonItem = UIBarButtonItem(barButtonSystemItem: .Done, target: self, action: #selector(InsertItemViewController.done))
        self.navigationItem.rightBarButtonItems = [doneButton]

        if self.itemToEdit.itemId != 0 {
            self.title = "Edit Note"
        }
        else {
            self.title = "Add Note"
        }
        self.notesField.text = notes
        self.notesField.delegate = self
    }

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

    override func scrollViewWillBeginDragging(scrollView: UIScrollView) {
        self.notesField.resignFirstResponder()
    }

    override func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
        if indexPath.section == 0 {
            cell.backgroundColor = TableCellBackgroundColor
        }
    }

    override func tableView(tableView: UITableView, willSelectRowAtIndexPath indexPath: NSIndexPath) -> NSIndexPath? {
        if indexPath.row == 0 {
            return indexPath
        } else {
            return nil;
        }
    }


    func textViewShouldBeginEditing(textView: UITextView) -> Bool {
        return true
    }

    func imageFromLayer(layer: CALayer) -> UIImage {
        layer.renderInContext(UIGraphicsGetCurrentContext()!)
        let outputImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return outputImage
    }
}

I am not able to identify the reason behind this error. Can anyone please take a look into the code and tell me what i am going wrong ? I am new to Swift, so please pardon my ignorence.

Answer 1

Your problem is that all the properties inside a class need to be initialized in the init or before, but need to be initialized, you can fix it declaring your delegate as Optional

As @Sultan said in his comment you should always implement your delegates using weak references to avoid any kind of retain-cycles, for do that you need to specify in your protocol that it always be implemented by classes, like in this way:

protocol AddItemViewControllerDelegate: class {
   func addItemViewControllerDidCancel(controller: InsertItemViewController)
   func addItemViewController(controller: InsertItemViewController, didFinishAddingItem item: ChecklistItem)
   func addItemViewController(controller: InsertItemViewController, didFinishEditingItem item: ChecklistItem)
}

And then you can do declare as a weak reference inside your class like this:

weak var delegate: AddItemViewControllerDelegate?

I hope this help you.

Answer 2

You are getting this error because of this line.

var delegate: AddItemViewControllerDelegate

Replace that line with this.

var delegate: AddItemViewControllerDelegate!

But if you are not initializing the delegate then it will crash. So to avoid crash, use the following.

var delegate: AddItemViewControllerDelegate?