CODEWITHSUNDEEP
swiftuitableviewswift3
Fr0zt
Fr0zt

Reputation: 1255

Going from one ViewController to another ViewController and updating

Now I have 3 Viewcontrollers like this:

HomeViewcontroller = VC1.
Viewcontroller2 = VC2 --> has a table view with cells on it.
Viewcontroller3 = VC3 --> allows me to edit each cell in VC2 or delete.

I am using NavigationController between Viewcontrollers, to get the nice "back" button :)

Lets say I am in VC1, I press a button and I go to VC2. Now let's say I have 4 cells. I press cell number 2 and I go to VC3, where I can edit what I have in the cell or even delete it. This is all working OK (tested it).

Let's say I want to delete that cell. I have a button on VC3 and I use it and I delete the cell (this is tested and also working OK).

Now when I do this I push into VC2 again like this:

let viewController = storyboard?.instantiateViewController(withIdentifier: "VC2") as! VC2!
self.navigationController?.pushViewController(viewController!, animated: true)

The problem is that when I do this I go to VC2 but I doesn't reload my tableView has it should (the erased cell it's still there).

To fix this I tried adding some code in VC2, in the viewDidLoad:

self.tableView.reloadData()

Now I managed to do it work. I mean when I delete a cell from VC3 I am pushed to VC2 and the cell it's not there. However If I press the back button it takes me to the previous cell that I have deleted,,, If the cell doesn't exist anymore I don''t want it to take me there. I want it to take me to the VC1 (home).

How can I make this work?

Perhaps I should do this in another way and not pushing like that?

Upvotes: 3

Views: 1236

Answers (4)

Hasya
Hasya

Reputation: 9898

Practically you are doing wrong, when delete / edit operation done on VC3 and you want to come back on VC2, why you are doing pushViewController , you have to apply popViewController.

You have to apply self.navigationController?.popViewController(animated: true) coming back to VC2 from VC3.

Remove

let viewController = storyboard?.instantiateViewController(withIdentifier: "VC2") as! VC2!
self.navigationController?.pushViewController(viewController!, animated: true)

Add 

self.navigationController?.popViewController(animated: true)

Also

Put reloadData() method for table view in viewWillAppear. like below code.

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

    self.tableView.reloadData()

}

Some reference material to read about UINavigationController.

https://developer.apple.com/reference/uikit/uinavigationcontroller

Upvotes: 2

MacUserT
MacUserT

Reputation: 1953

N.,

Normally when different view controllers are embedded in a navigation controller, you push up the stack and going back you pop from the stack. As I understand your story it seems you are only pushing new view controllers on the stack.

Your first view controller is VC1. You press a button and you push the new view controller on the stack, VC2. The navigation controller now has 2 view controllers on the stack VC1 and VC2. Then you select a cell in the table view of VC2 and it takes you to VC3.

The navigation controller now holds 3 view controllers on the stack VC1, VC2 and VC3. Now you delete a cell and you push a NEW view controller on the stack, which is again a VC2, but a new one. The navigation controller now has four view controllers on the stack VC1, VC2, VC3 and another instance of VC2.

I would assume you have a model object containing the data in the table views of VC2 and VC3. When you delete the cell you should delete the cell in your model object and not push a new VC2 on the stack, but dismiss the VC3. You can do this with an @IBAction in VC2 to which your delete button is connected. It then pops the VC3 from the stack and you land back in VC2 in the IBAction method to which you have linked the delete button. The navigation controller then only has 2 view controllers on the stack again, VC1 and VC2.

In that IBAction method you can reload the table view and the table view will call the datasource method 

tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell

This method will look at your model object and not find the deleted data and your cell is gone.

When you then push the back button, the navigation controller pushes the VC2 from the stack and is left with only one view controller VC1. You will land back on your page.

Hope this helps.

Upvotes: 1

Nirav D
Nirav D

Reputation: 72460

Instead of pushing ViewController2 again from ViewController3 you need to create one delegate and implement that delegate within your ViewController2 now create the instance of that delegate in viewController3 and set that delegate when you are moving from ViewController2 to ViewController3. Now when you update or delete data of ViewController2's simply use that delegate to call method from ViewController2 and inside that method update your DataSource and reload the tableView.

Upvotes: 1

vacawama
vacawama

Reputation: 154711

Put your self.tableView.reloadData() in an override of viewWillAppear. viewDidLoad is only called once after the viewController is created, but viewWillAppear is called every time it is about to appear on screen.

Also, don't use a push to return to VC2 from VC3. You should pop the current viewController.

self.navigationController?.popViewController(animated: true)

Upvotes: 2

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