Get section header cell in gesture method - ios

Question

I am working on a 'UITableView' with different section headers. Section header contains a tab gesture recognization to expand and collapse the section.
In the section header view, I have used an image for the accessory icon to show the user the section is expanded or collapsed.
My concern is when I tap section header then control goes to the gesture method. In that method how should I get the header cell to update the image accordingly?
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView?
{
if self.useSearchDefinitions {
if let ret = tableView.dequeueReusableCell(withIdentifier: INBOX_HEADER_CELL_IDENTIFIER) as? InboxHeaderCell {
ret.contentView.backgroundColor = UIColor(red: 236 / 255.0, green: 236 / 255.0, blue: 236 / 255.0, alpha: 1.0)
ret.contentView.tag = section
ret.lblHeaderTitle?.textColor = UIColor(red: 110 / 255.0, green: 110 / 255.0, blue: 110 / 255.0, alpha: 1.0)
ret.lblHeaderTitle?.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.headline)
ret.lblHeaderTitle?.text = presenter.sectionTitle(section)
ret.accessoryImage.image = UIImage(named: "inbox-expand.png")
// Set tap gesture
let headerViewTapRecognizer = UITapGestureRecognizer(target: self, action: #selector(self.headerViewGestureHandler))
headerViewTapRecognizer.delegate = self
headerViewTapRecognizer.numberOfTouchesRequired = 1
headerViewTapRecognizer.numberOfTapsRequired = 1
ret.contentView.addGestureRecognizer(headerViewTapRecognizer)
return ret.contentView
}
}
return nil
}
and this is to get the gesture
func headerViewGestureHandler(_ sender: UIGestureRecognizer)
{
tableView.beginUpdates()
if let tag = sender.view?.tag {
let section = Int(tag)
let shouldCollapse: Bool = !collapsedSections.contains((section))
let numOfRows = Int(presenter.numberOfRows(tag))
}
}
how should I get the particular clicked section header cell in this method so I can update the image accordingly?
Thanks in advance.

Answer 1

I would recommend:
put the Gesture code inside your section header
using a "call back" closure for passing the tap back to the view controller
Here is a simple example (assumes you have a View Controller with a Table View, hooked up via IBOutlet):
class SimpleSectionHeaderView: UITableViewHeaderFooterView, UIGestureRecognizerDelegate {
// typical UILabel
var lblHeaderTitle: UILabel = {
let v = UILabel()
v.translatesAutoresizingMaskIntoConstraints = false
return v
}()
// this is our "call back" closure
var headerTapCallback: (() -> ())?
func headerViewGestureHandler(_ sender: UIGestureRecognizer) {
// just for debugging, so we know the tap was triggered
print("tapped!!!")
// "call back" to the view controller
headerTapCallback?()
}
func commonInit() {
// set our backgroundColor
contentView.backgroundColor = .cyan
// add a label and set its constraints
self.addSubview(lblHeaderTitle)
lblHeaderTitle.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 8.0).isActive = true
lblHeaderTitle.centerYAnchor.constraint(equalTo: self.centerYAnchor, constant: 0.0).isActive = true
// Set tap gesture
let headerViewTapRecognizer = UITapGestureRecognizer(target: self, action: #selector(self.headerViewGestureHandler))
headerViewTapRecognizer.delegate = self
headerViewTapRecognizer.numberOfTouchesRequired = 1
headerViewTapRecognizer.numberOfTapsRequired = 1
// add it to self
self.addGestureRecognizer(headerViewTapRecognizer)
}
override init(reuseIdentifier: String?) {
super.init(reuseIdentifier: reuseIdentifier)
commonInit()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
}
class TableWithSectionHeadersViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var theTableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
// standard cell registration
theTableView.register(UITableViewCell.self, forCellReuseIdentifier: "reuseIdentifier")
theTableView.register(SimpleSectionHeaderView.self, forHeaderFooterViewReuseIdentifier: "simpleHeaderView")
// make sure these are set (in case we forgot in storyboard)
theTableView.delegate = self
theTableView.dataSource = self
}
func handleHeaderTap(_ section: Int) -> Void {
// do whatever we want based on which section header was tapped
print("View Controller received a \"tapped\" in header for section:", section)
}
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let v = tableView.dequeueReusableHeaderFooterView(withIdentifier: "simpleHeaderView") as! SimpleSectionHeaderView
// set the view's label text
v.lblHeaderTitle.text = "Section \(section)"
// set the view's "call back" closure
v.headerTapCallback = {
_ in
self.handleHeaderTap(section)
}
return v
}
func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 60;
}
// MARK: - Table view data source
func numberOfSections(in tableView: UITableView) -> Int {
return 5
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 4
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath)
// Configure the cell...
cell.textLabel?.text = "\(indexPath)"
return cell
}
}
This also eliminates any need to set any .tag properties (which is generally a bad idea, for a number of reasons).