无法在 HeaderView 中添加 UISearchBar（tableview 的 header 视图）？

Question

Not able to see the searchBar in tableView section header everthing is done programmatically no storyboards used

import UIKit

class ConversationsViewController: UITableViewController {
    
    
    
    let searchBar:UISearchBar = {
        let bar = UISearchBar()
        bar.placeholder = "search conversations"
        bar.translatesAutoresizingMaskIntoConstraints = false
        return bar
    }()
    let headerView:UIView = {
        let hView = UIView()
//        hView.backgroundColor = .red
        hView.translatesAutoresizingMaskIntoConstraints = false
        return hView
        
    }()
    //    we want custom cell and header view
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Do any additional setup after loading the view.
    }
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

    }
//    override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
//        return "section \(section)"
//    }
    override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        headerView.addSubview(searchBar)
        searchBar.centerXAnchor.constraint(equalTo: headerView.centerXAnchor).isActive = true
        searchBar.centerYAnchor.constraint(equalTo: headerView.centerYAnchor).isActive = true
        searchBar.heightAnchor.constraint(equalToConstant: 100).isActive = true
        searchBar.widthAnchor.constraint(equalToConstant: 40).isActive = true
        return headerView
    }
    override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
        return 70
    }
}

here is the output photo

I tried diff ways but I found this method to add headerView in tableView and now I can't figure out how to add that search bar in headerView, I tried above but it doesn't work, please help thank you

Answer 1

Couple things...

A view for a section header should NOT have .translatesAutoresizingMaskIntoConstraints set to false . Leave it at the default of true .

Don't give the UISearchBar a height constraint -- let it use its intrinsic height.

We DO need to give the search bar a width constraint. If you want it to fit the width of the table, use:

searchBar.widthAnchor.constraint(equalTo: headerView.widthAnchor, constant: 0.0).isActive = true

If you want it to be only partial width, either give that line a negative value for the constant , or use a multiplier:

// this will make the search bar 90% of the width of the table
searchBar.widthAnchor.constraint(equalTo: headerView.widthAnchor, multiplier: 0.9).isActive = true

Here is your class with those modifications:

class ConversationsViewController: UITableViewController {
    
    let searchBar:UISearchBar = {
        let bar = UISearchBar()
        bar.placeholder = "search conversations"
        bar.translatesAutoresizingMaskIntoConstraints = false
        return bar
    }()

    let headerView:UIView = {
        let hView = UIView()

        // give it a background color so we can easily see
        //  if it is laying out correctly
        hView.backgroundColor = .red

        // section header view should leave this at the default TRUE
        //hView.translatesAutoresizingMaskIntoConstraints = false

        return hView
    }()

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        // add the searchBar
        headerView.addSubview(searchBar)
        
        // center it horizontally and vertically
        searchBar.centerXAnchor.constraint(equalTo: headerView.centerXAnchor).isActive = true
        searchBar.centerYAnchor.constraint(equalTo: headerView.centerYAnchor).isActive = true
        
        // don't set height constraint - use UISearchBar intrinsic height
        //searchBar.heightAnchor.constraint(equalToConstant: 100).isActive = true
        
        // constrain width equal to headerView width
        //  we can adjust the constant if we don't want it to span the entire width of the table
        //  by using a negative value for the constant, or using a mulitplier to get a percent of the width
        searchBar.widthAnchor.constraint(equalTo: headerView.widthAnchor, constant: 0.0).isActive = true
        
        return headerView
    }
    
    override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
        return 70
    }
    
}