解开核心数据中的可选值时发现nil

Question

I've been trying to address this issue for a few days and it seems I'm only going in circles.

I'm adding data to core data by tapping on tableView cells and then displaying the items on another tableView .

That works great, the problem is this:

When I click on the other table view rows, to be able to see the item with all the other values stored in core data, I get

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value on the showMeTheGoodiesTwo(entry: myCart) line 

...Inside viewDidLoad . But I do not know why that's happening, as the entity is not empty.

Here's the code of the view controller where I want to display the item's details.

Hope somebody can give me a hand.

Cheers!

import UIKit

class productQuantityViewController: UIViewController {

    var myCart: Cart!

    @IBOutlet weak var productImage: UIImageView!
    @IBOutlet weak var productNameLabel: UILabel!
    @IBOutlet weak var productDescriptionLabel: UILabel!
    @IBOutlet weak var productAmountLabel: UITextField!
    @IBOutlet weak var minusButton: UIButton!
    @IBOutlet weak var plusButton: UIButton!


    override func viewDidLoad() {
        super.viewDidLoad()

        productImage.layer.cornerRadius = 10
        minusButton.layer.cornerRadius = minusButton.frame.size.width/2
        plusButton.layer.cornerRadius = plusButton.frame.size.width/2

        showMeTheGoodiesTwo(entry: myCart)

    }


    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    func showMeTheGoodiesTwo(entry: Cart) {

        let name = entry.product
        let quantity = entry.inventory
        let description = entry.productDescription

        let image = entry.productImage as Data?
        let xNSNumber = quantity as NSNumber

        productNameLabel!.text = name
        productDescriptionLabel!.text = description
        productAmountLabel!.text = xNSNumber.stringValue
        productImage!.image = UIImage(data:image!)

        print(productNameLabel.text as Any)

    }


}

Answer 1

You need to change

var myCart: Cart! 

To

var myCart: Cart?

? is use to make it optional. And in viewDidLoad use

if (myCart != nil){
            showMeTheGoodiesTwo(entry: myCart)
        } else {
            //do something.
        }

instead of

showMeTheGoodiesTwo(entry: myCart)