iOS tableHeaderView in UITableViewController never displayed - ios

Question

I'm trying to implement a tableViewHeader (and not "viewForHeaderInSection") for my tableview in a UITableViewController "TBVC1".
I tried two solution (don't work of course...):
1ST : Added a UIView in the top of my UITableViewController in my storyboard. If I add a UILabel (with constraints etc) in this UIView, and try to display my View TBVC1.... I see nothing. The full View is empty. But, if I delete the UILabel inserted in the header UIView, I can see all my cells and the headerView background Color...
Do you have any idea why I can't put any UI component in this UIView?
2ND : If I try load a specific nib UIView like this :
Bundle.main.loadNibNamed("Title", owner: nil, options: nil)!.first as! UIView
self.tableView.setTableHeaderView(headerView: customView)
self.tableView.updateHeaderViewFrame()
extension UITableView {
/// Set table header view & add Auto layout.
func setTableHeaderView(headerView: UIView) {
headerView.translatesAutoresizingMaskIntoConstraints = false
// Set first.
self.tableHeaderView = headerView
// Then setup AutoLayout.
headerView.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
headerView.widthAnchor.constraint(equalTo: self.widthAnchor).isActive = true
headerView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
}
/// Update header view's frame.
func updateHeaderViewFrame() {
guard let headerView = self.tableHeaderView else { return }
// Update the size of the header based on its internal content.
headerView.layoutIfNeeded()
// ***Trigger table view to know that header should be updated.
let header = self.tableHeaderView
self.tableHeaderView = header
}
}
it doesn't work too... my full View is empty...
Do you have any ideas why I don't succeed to display a simple UILabel in my UIView for the tableViewheader?

Answer 1

I'm not sure my way is proper, but every time I set tableHeaderView, I also set its height manually.
If you want to use auto-layout in your tableHeaderView, you can call systemLayoutSizeFitting(UIView.layoutFittingCompressedSize) on the header view to get the calculated size and assign the height to headerView.
You can try this simple example in Playground.
import UIKit
import PlaygroundSupport
class MyViewController: UITableViewController {
override func loadView() {
super.loadView()
let headerView = UIView()
headerView.backgroundColor = .red
let label = UILabel()
label.translatesAutoresizingMaskIntoConstraints = false
label.text = "Hello World!"
label.textAlignment = .center
label.textColor = .white
headerView.addSubview(label)
let attributes: [NSLayoutConstraint.Attribute] = [.leading, .top, .centerX, .centerY]
NSLayoutConstraint.activate(attributes.map {
NSLayoutConstraint(item: label, attribute: $0, relatedBy: .equal, toItem: headerView, attribute: $0, multiplier: 1, constant: 0)
})
// We have to set height manually, so use `systemLayoutSizeFitting` to get the layouted height
headerView.frame.size.height = headerView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize).height
tableView.tableHeaderView = headerView
}
}
PlaygroundPage.current.liveView = MyViewController()