Swift - 从另一个 ViewController 在 TableView 中插入项目

Question

I am having a problem where I seem to add items to a tableView in another ViewController but they don't appear if presenting the VC.

I am also having different tableViews which makes it a bit more difficult:

This is inside my first ViewControllerA from where I can access the 2nd ViewControllerB :

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    // if indexPath.item is less than data count, return a "Content" cell
    if indexPath.item < wishListTitlesArray.count {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ContentCell", for: indexPath) as! ContentCell

        cell.cellLabel.text = wishListTitlesArray[indexPath.item]

        cell.buttonView.setImage(wishListImagesArray[indexPath.item], for: .normal)

        cell.customWishlistTapCallback = {

            // track selected index
            self.currentWishListIDX = indexPath.item

            let vc = self.storyboard?.instantiateViewController(withIdentifier: "WishlistVC") as! WishlistViewController
            // set image
            vc.wishlistImage.image = self.wishListImagesArray[indexPath.item]
            // set label
            vc.wishlistLabel.text = self.wishListTitlesArray[indexPath.item]
            // set wishlist
            vc.theTableView.wishList = self.userWishListData[indexPath.item]

            vc.currentWishListIDX = self.currentWishListIDX

            vc.userWishListData = self.userWishListData

            vc.theTableView.tableView.reloadData()
            self.present(vc, animated: true, completion: nil)

        }

        return cell
    }

func insertWish(){

    insertWishDelegate?.insertWish(wishName: popUpView.whishName!, idx: selectedWishlistIDX!, currentWishlistIDX: currentWishListIDX,data: userWishListData)

    // save Wish to database -> DataHandler
    saveWish()

}

And this is inside my 2nd ViewController:

func insertWish(wishName: String, idx: Int, currentWishlistIDX: Int, data: [[Wish]]) {
    // append the new wish to the user's currently selected wishlist
    var wishes: [Wish] = data[idx]
    wishes.append(Wish(withWishName: wishName, checked: false))
    userWishListData[currentWishlistIDX] = wishes
    // set the updated data as the data for the table view
    theTableView.wishList = userWishListData[currentWishlistIDX]
    theTableView.tableView.reloadData()
}

Presenting the 2nd ViewController works just fine. All the variables I pass are the right ones. The only problem I have is that I am not able to insert a "Wish". There is no error or something. The user can add Wishes from the first ViewController:

@objc func wishButtonTapped(){
    dismissPopUpView()
    insertWish()
}

For the whole project you can look at my git (very messy though): Git Project

I probably miss something very basic but I can not get behind what it is so I am very grateful for every help :)

Answer 1

Your code cannot work because you are accessing UI elements in vc which are not connected (yet) right after instantiating the view controller.

Secondly you are strongly discouraged from using multiple arrays for the data source. Never do that. Create a custom struct to hold all parameters of one item (in the code below called Item ) and use one data source array (called datasourceArray ).

Then assign the item to a temporary variable ( wishList in vc ) and assign the values to the UI elements in viewDidLoad

This example assumes that the values from the three arrays ( image , title and data ) are in one instance of the custom struct. You have to redesign the entire data model. In the closure pass the Item instance to vc

cell.customWishlistTapCallback = {

        // track selected index
        self.currentWishListIDX = indexPath.item

        let vc = self.storyboard?.instantiateViewController(withIdentifier: "WishlistVC") as! WishlistViewController
        vc.wishlist = datasourceArray[indexPath.item]
        vc.currentWishListIDX = self.currentWishListIDX
        vc.userWishListData = self.userWishListData
        self.present(vc, animated: true, completion: nil)
    }

and in vc in viewDidLoad populate the UI elements and reload the table view

var wishList : Item!

override func viewDidLoad()
    super.viewDidLoad()
    wishlistImage.image = wishList.image
            // set label
    wishlistLabel.text = wishList.title
            // set wishlist
    theTableView.wishList = wishList.data
    theTableView.tableView.reloadData()
}