Passing Data Forward In Swift Without Segue

Question

I'm currently making a to do list app using Swift 4. The home view controller has a tableview with some categories in it and when one is selected, it takes the user to a view controller where the items in that category are listed. I have a bug however as only the most recent item is showing in the list.

I think this is due to the way I am navigating to the list view controller. I am currently doing this:

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let destinationVC = ListVC()
    if let indexPath = tableView.indexPathForSelectedRow {
        destinationVC.selectedCategory = categoryArray[indexPath.row]
    }
    navigationController?.pushViewController(destinationVC, animated: true)
    
    tableView.deselectRow(at: indexPath, animated: true)
}

And in the list view controller, I just have this to load the data:

var selectedCategory : Category? {
    didSet {
        loadItems()
    }
}

I firstly created this app using storyboards and when using segues, it worked completely fine.

override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    performSegue(withIdentifier: "goToItems", sender: self)
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    let destinationVC = segue.destination as! TodoListVC
    
    if let indexPath = tableView.indexPathForSelectedRow {
        destinationVC.selectedCategory = categoryArray[indexPath.row]
    }
}

So basically, the problem is that in the secondary list view controller, it will only show the most recently added item and no other ones even when they are stored in core data. I think it is to do with the way I am showing the secondary view controller as I am creating a new object every time.

How to properly go to the next view controller?

Answer 1

Remove the segue and add the storyboard id

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let vc = self.storyboard?.instantiateViewController(withIdentifier: "storyboard_id") as! TodoListVC
        vc.selectedCategory = categoryArray[indexPath.row]
        self.navigationController?.pushViewController(vc, animated: true)
    }

Answer 2

Try this it will help you:-

You can send data from one view controller to another using storyboard instance.

let next = self.storyboard?.instantiateViewController(withIdentifier: "NextControllerStoryBoard_id")as! NextController

next.str = "data which you want to pass"

self.navigationController?.pushViewController(next, animated: true)

here NextController is your controller class name where you want to go.str is the string name which you declare on NextController like

let str = String() you are able to send string in that variable in same way you send any thing array dictionary ,image, Int value etc.

NextControllerStoryBoard_id is id which you declare at storyboard of that controller

In storybard id add your storybard id

Hope this will help you

Answer 3

I think that with this chunk of code I already sensed that you are passing data to the other view controller the incorrect way:

let destinationVC = ListVC()
if let indexPath = tableView.indexPathForSelectedRow {
    destinationVC.selectedCategory = categoryArray[indexPath.row]
}

...

What I would suggest is that, instead of passing the data this way, you have to pass an array containing the items within the selected category using an array, then pass that array via the prepare for segue.

Then from the viewdidappear or viewdidload method in the receiving view controller, use the passed array from the source VC and use that as a datasource for your table view within that 2nd VC.