迅速4无法将类型UIView的值转换为UITableViewHeaderFooterView

Question

I have a class for a table view declared as:

class boatsVC: UIViewController, UITableViewDelegate, UITableViewDataSource {

In this class, I want to change the background color and the text color for the sections. To this end, I have implemented the following two classes:

func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
    let view = UIView()
    view.backgroundColor = Constants.ppsBlue
    return view
}

func tableView(_ tableView: UITableView, willDisplayHeaderView view: UIView, forSection section: Int) {
    let header = view as! UITableViewHeaderFooterView
    header.textLabel?.textColor = UIColor.white
}

When I run the code, I get a Thread 1: signal SIGABRT on the

let header = view as! UITableViewHeaderFooterView

line of the willDispayHeaderView function. If I comment out all of the code in both of these functions, the app runs as it should and I get the section title displaying correctly. But it isn't in the colors which I'd like to be using. All I'm trying to do is change the background color for the section and change the text color. If I comment out the code in the willDisplayHeaderView function, the app works, the section background color is the color I want, but I do not see the title of the section.

Any ideas?

Answer 1

Ok, here's what I did to fix this problem. I created a new class of type UITableViewHeaderFooterView:

protocol BoatHeaderViewDelegate {
func toggleSection(header: BoatHeaderView, section: Int)
}

class BoatHeaderView: UITableViewHeaderFooterView {

    var delegate: BoatHeaderViewDelegate?
    var section: Int!

    override init(reuseIdentifier: String?) {
        super.init(reuseIdentifier: reuseIdentifier)
        self.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(selectHeaderAction)))
    }


    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }


    @objc func selectHeaderAction(gestureRecognizer: UITapGestureRecognizer) {
        let cell = gestureRecognizer.view as! BoatHeaderView
        delegate?.toggleSection(header: self, section: cell.section)
    }

    func customInit(title: String, section: Int, delegate: BoatHeaderViewDelegate) {
        self.textLabel?.text = title
        self.section = section
        self.delegate = delegate
    }


    override func layoutSubviews() {
        super.layoutSubviews()
        self.textLabel?.textColor = UIColor.white
        self.contentView.backgroundColor = Constants.ppsBlue
    }
}

Then, in my boatsVC class:
1) I added the BoatHeaderViewDelegate to the class definition
2) I created a toggleSection
3) I removed the willDisplayHeaderView function
4) I changed the viewForHeaderInSection as follows:

func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
    let header = BoatHeaderView()
    header.customInit(title: thisRaceName, section: 1, delegate: self)
    return header
}

Now, when I run the app, the background color and the text color for the section is what I need it to be.

Answer 2

You can achieve it simply through a single function by,

 func tableView(_ tableView: UITableView, willDisplayHeaderView view: UIView, forSection section: Int){

    view.tintColor = UIColor.clear
    let header = view as! UITableViewHeaderFooterView
    header.textLabel?.textColor = UIColor.red
}