How to update UITableview Header height while scrolling programatically

Question

In My application I have top navigation bar and a tableview below the navigation bar. I have CollectionViewCell with two rows which added inside the UITableViewHeader programmatically. When ever I scroll the the TableView to top, i want the header to stop just below the navigation bar, and update the TableView Header height so I can show only one row. I just want to do an animation (like Shrinked)when the TableViewHeader sticks to the navigationbar the two collectionview rows should turn into one row by decreasing the Header Height. How can I do it programmatically

Below is my code for showing CustomHeaderView

func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
    let headerView = UIView.init(frame: CGRect(x: 0, y: 0, width: self.view.frame.width, height: 183))
    let headerCell = tableView.dequeueReusableCell(withIdentifier: kLastPlayedidentifier) as! LastPlayedTVC
    headerCell.frame = headerView.frame
    headerCell.category = lastPlayedData
    headerView.addSubview(headerCell)
    return headerView
}

Also i'm checking for the scroll position to set the tableview header height progmmatically which isn't successful for me.

    func scrollViewDidScroll(_ scrollView: UIScrollView) {
    print(scrollView.contentOffset)
    if scrollView.contentOffset.y > 237 //This value is to check when the header reached the top position {
//Condition to check and animate the headerview height to make collectionview cell two rows into one rows.
    }

How can I achieve the TableViewHeader height update when header sticks on top while scrolling.

Any help is appreciated.

[Read this. Near the bottom is an answer uses Swift.](https://stackoverflow.com/questions/2659428/how-to-animate-the-height-change-of-an-section-header-in-uitableview) — AgRizzo, Aug 05 '19 at 18:01
@AgRizzo Nope this din't helped me out, but it made sense to me. I have created utiableviewcell with collectionviewcells inside it programatically, is that causing the headerview height to be fixed even when i update the frame it is not changing. Any idea what might be the problem? — Madhu, Aug 05 '19 at 18:48

Chris · Answer 1 · 2019-08-06T23:12:21.547

What you are looking for is "sticky header" and you want to change the header as well.

Sticky part is built in automatically I think if you just use UITableViewController(style: .plain), if that doesn't work for you, you can just google sticky header and there are lots of answers.
the part about changing the height or animating it. you are doing it right, just do something like:

// update your viewForHeader method to account for headerRows variable above

// update your viewForHeader method to account for headerRows variable above

// default 2, you modify this in your scroll
var headerRows = 2

    func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? { 
let height = headerRows == 2 ? 183 : 91
        let headerView = UIView.init(frame: CGRect(x: 0, y: 0, width: self.view.frame.width, height: height))
        let headerCell = tableView.dequeueReusableCell(withIdentifier: kLastPlayedidentifier) as! LastPlayedTVC
        headerCell.frame = headerView.frame
        headerCell.category = lastPlayedData
        headerView.addSubview(headerCell)
        return headerView
    }

    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        print(scrollView.contentOffset)
        if scrollView.contentOffset.y > 237 {
            updatedHeader.frame.size.height = 40
            self.tableviewObj.tableHeaderView = updatedHeader
            headerRows = 1 } else {
            headerRows = 2
        }
        self.tableView.reloadSectionHeaders()
    }

If you want to do some animating instead, what you would do is store reference to your headerView in a variable of your view controller and inside your scrollViewDidScroll animate it using UIView.animate{...}

hope this helps man.

Thank you for your comment. i'm showing header only for particular section, when i try to update the header height it isn't updating. Do we need to user begin update and endupdates on tableview? i have update my question , please have a look and help me out. Thanks — Madhu, Aug 06 '19 at 10:27
beginupdate and endupdate are only a transaction thing, its for performing multiple operations (similar to database) in single transaction. someone suggested an edit with more detail which is good, hopefully this clarifies a bit. — Chris, Aug 06 '19 at 23:10

How to update UITableview Header height while scrolling programatically

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