Refresh Certain Row of Uitableview Based on Int in Swift

Refresh certain row of UITableView based on Int in Swift

You can create an NSIndexPath using the row and section number then reload it like so:

let indexPath = NSIndexPath(forRow: rowNumber, inSection: 0)
tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Top)

In this example, I've assumed that your table only has one section (i.e. 0) but you may change that value accordingly.

Update for Swift 3.0:

let indexPath = IndexPath(item: rowNumber, section: 0)
tableView.reloadRows(at: [indexPath], with: .top)

How to reload and animate just one UITableView cell/row?

Use the following UITableView instance method:

- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation

You have to specify an NSArray of NSIndexPaths that you want to reload. If you just want to reload. If you only want to reload one cell, then you can supply an NSArray that only holds one NSIndexPath. For example:

NSIndexPath* rowToReload = [NSIndexPath indexPathForRow:3 inSection:0];
NSArray* rowsToReload = [NSArray arrayWithObjects:rowToReload, nil];
[myUITableView reloadRowsAtIndexPaths:rowsToReload withRowAnimation:UITableViewRowAnimationNone];

You can see the UITableViewRowAnimation enum for all the possible ways of animating the row refresh. If you don't want any animation then you can use the value UITableViewRowAnimationNone, as in the example.

Reloading specific rows has a greater advantage than simply getting the animation effect that you'd like. You also get a huge performance boost because only the cells that you really need to be reloaded are have their data refreshed, repositioned and redrawn. Depending on the complexity of your cells, there can be quite an overhead each time you refresh a cell, so narrowing down the amount of refreshes you make is a necessary optimization that you should use wherever possible.

How to Refresh particular cell in tableview and store that changed data to show later on same tableview

You need to maintain the state of your UITableViewCell in your tableView's dataSource model. I'll try to elaborate that through an example.

1. Let's assume you model looks something like:

class Post {
    var isLiked = false
    var likeCount = 0
}

2. Next, you need to create the custom UITableViewCell such that it modifies the dataSource and the UI as per the button action, i.e.

class CustomCell: UITableViewCell {
    @IBOutlet weak var countLabel: UILabel!
    @IBOutlet weak var likeButton: UIButton!

    var post: Post?

    func configure(with post: Post) {
        countLabel.text = "\(post)"
        likeButton.isSelected = post.isLiked
    }

    @IBAction func likeButtonTapped(_ sender: UIButton) {
        sender.isSelected = !sender.isSelected
        if let post = post {
            post.isLiked = sender.isSelected
            if sender.isSelected {
                post.likeCount += 1
            } else {
                post.likeCount -= 1
            }
            countLabel.text = "\(post.likeCount)"
        }
    }
}

3. Finally, the UITableViewDataSource methods will be,

class VC: UIViewController, UITableViewDataSource {
    var posts = [Post]()

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return posts.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! CustomCell
        cell.configure(with: posts[indexPath.row])
        return cell
    }
}

In the above code, whenever the likeButton is pressed, the UI and the dataSource will be updated. So, whenever the cell is displayed again, you'll see the last updated data automatically.

There is no need to reload the tableView or cell everytime the likeButton is tapped. Reloading will only result in the extra overhead.

Swift: How to reload new content (eg. array) every time the tableview appears?

Your reloadData() call is before updating array.

It should be after updating the datasource:

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

    weightArray = UserDefaults.standard.array(forKey: "favorites") as! [String]
    tableView.reloadData()    
}

---

Anyways, you can make use of the didSet property observer of your datasource object.

//your weightArray declaration
var weightArray = [String]() {
    didSet {
        tableView.reloadData()
    }
}

and then you can do:

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

    weightArray = UserDefaults.standard.array(forKey: "favorites") as! [String]   
}

This way, anytime you change the array, your tableView will reload.

Swift UITableView messing up after reloadData()

This is because of the reuse of cells.

Set the default color in else condition.

} else {
  cell.cost.textColor = UIColor.gray
  cell.cost.text = "\(items[indexPath.row].XP) XP"
}

Another way, you can set the default style property inside the prepareForReuse method of UITableViewCell

class TableViewCell: UITableViewCell {
    override func prepareForReuse() {
        super.prepareForReuse()
        // Set default cell style
    }
}

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