无法更改标题中的按钮标题

如何解决无法更改标题中的按钮标题

我有一个带有标题的 UICollectionView VC。这个标题是一个自定义单元格，在该单元格内有一个按钮可以打开 UITableView（下拉菜单）。

每当我点击该按钮并选择一个值时，我都需要更改该按钮标题，但我一定是做错了什么，因为它没有改变。

您可以在 UITableView 下面看到 didSelectRowAt 我做了以下操作：

let title = self.dropdownDataSource[indexPath.row]
selectedButton.setTitle(title,for: .normal)

HeaderCell

protocol HeaderCellDelegate: class {
    func setDropdown()
    func tapOnSelection()
}

class HeaderCell: UIGestureRecognizerDelegate {

    // delegate
    weak var hDelegate: HeaderCellDelegate?

    @objc
    lazy var selectionBtn: UIButton = {
        let button = UIButton(type: .system)
        button.setTitle("One",for: .normal)
        button.addTarget(self,action: #selector(changeSelection),for: .touchUpInside)
        return button
    }()
    
    @objc
    lazy var oneOrTwo: UIButton = {
        let button = UIButton()
        button.setimage(UIImage(named: "oneOff")?.withRenderingMode(.alwaystemplate),action: #selector(toggleOneOrTwo),for: .touchUpInside)
        return button
    }()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
    
        // I setup view helper
        // Just a button and icon on the right
        // button opens DropDown list
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    // MARK: - Delegate Functions
    
    @objc
    func toggleOneOrTwo(_ sender: Any) {
        self.hDelegate?.setDropdown()
    }
    
    @objc
    func changeSelection(sender: UIButton) {
        self.hDelegate?.tapOnSelection()
    }
}

视图控制器

class CellClass: UITableViewCell {
}

class ViewController: UICollectionViewController,UIGestureRecognizerDelegate {

    let transparentView = UIView()
    let tableView = UITableView()
    var dropdownDataSource: [String] = ["One","Two"]
    var selectedButton = UIButton()
    fileprivate let headerCellId = "headerCellId"
    lazy var headerCell = HeaderCell()

    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Register Cell Class
        self.collectionView.register(HeaderCell.self,forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader,withReuseIdentifier: headerCellId)

        // Dropdown table
        tableView.delegate = self
        tableView.dataSource = self
        tableView.register(CellClass.self,forCellReuseIdentifier: "Cell")
    }

    override func collectionView(_ collectionView: UICollectionView,viewForSupplementaryElementOfKind kind: String,at indexPath: IndexPath) -> UICollectionReusableView {
        switch kind {
        case UICollectionView.elementKindSectionHeader:
            let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind,withReuseIdentifier: headerCellId,for: indexPath) as! HeaderCell
            header.backgroundColor = .groupTableViewBackground
            header.hDelegate = self
            
            return header
        default:
            fatalError("This should never happen!!")
        }
    }

    // This is for the background of dropdown view
    func addTransparentView(frames: CGRect) {
         let window = UIApplication.shared.keyWindow
         transparentView.frame = window?.frame ?? self.view.frame
         self.view.addSubview(transparentView)
    
         tableView.frame = CGRect(x: frames.origin.x,y: frames.origin.y + frames.height,width: frames.width,height: 0)
         self.view.addSubview(tableView)
         tableView.layer.cornerRadius = 5
         
         transparentView.backgroundColor = UIColor.black.withAlphaComponent(0.9)
         tableView.reloadData()
         let tapgesture = UITapGestureRecognizer(target: self,action: #selector(removeTransparentView))
         transparentView.addGestureRecognizer(tapgesture)
         transparentView.alpha = 0
         UIView.animate(withDuration: 0.4,delay: 0.0,usingSpringWithdamping: 1.0,initialSpringVeLocity: 1.0,options: .curveEaseInOut,animations: {
             self.transparentView.alpha = 0.5
             self.tableView.frame = CGRect(x: frames.origin.x + 200,y: frames.origin.y + frames.height + 5,width: frames.width + 130,height: CGFloat(self.dropdownDataSource.count * 50))
         },completion: nil)
     }
    
    @objc
    func removeTransparentView() {
        let frames = selectedButton.frame
        UIView.animate(withDuration: 0.4,animations: {
             self.transparentView.alpha = 0
             self.tableView.frame = CGRect(x: frames.origin.x,height: 0)
         },completion: nil)
     }
}

extension ViewController: HeaderCellDelegate {
    func setDropdown() {
        // do something
    }
    
    func tapOnSelection() {
        selectedButton = headerCell.selectionBtn
        addTransparentView(frames: headerCell.selectionBtn.frame)
    }
}

extension ViewController: UITableViewDelegate,UITableViewDataSource {
    func tableView(_ tableView: UITableView,numberOfRowsInSection section: Int) -> Int {
        return dropdownDataSource.count
    }
    
    func tableView(_ tableView: UITableView,cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell",for: indexPath)
        cell.textLabel?.text = dropdownDataSource[indexPath.row]
        cell.textLabel?.font = UIFont.openSansFontOfSize(14)
        return cell
    }
    
    func tableView(_ tableView: UITableView,heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 50
    }
    
    func tableView(_ tableView: UITableView,didSelectRowAt indexPath: IndexPath) {
        tableView.deselectRow(at: indexPath,animated: true)
        let title = self.dropdownDataSource[indexPath.row]
        selectedButton.setTitle(title,for: .normal)
        removeTransparentView()
    }
}

解决方法

首先取headerView Globly

var headerView: DemoHeaderView?

现在viewForSupplementaryElementOfKind函数

func collectionView(_ collectionView: UICollectionView,viewForSupplementaryElementOfKind kind: String,at indexPath: IndexPath) -> UICollectionReusableView {
  // 1
  switch kind {
  // 2
  case UICollectionView.elementKindSectionHeader:
    // 3
    guard
        let headerView = collectionView.dequeueReusableSupplementaryView(
        ofKind: kind,withReuseIdentifier: "DemoHeaderView",for: indexPath) as? DemoHeaderView
      else {
        fatalError("Invalid view type")
    }

    self.headerView = headerView
    self.headerView?.label.text = "Demo"
    return self.headerView ?? UICollectionReusableView()
  default:
    // 4
    assert(false,"Invalid element type")
  }
}

和 UICollectionReusableView（我使用标签进行演示）

   class DemoHeaderView: UICollectionReusableView {
      @IBOutlet weak var label: UILabel!
    }

现在在 didSelectRowAt

 guard let header = self.headerView else { return }
        header.label.text = "Button Tapped"

希望能帮到你。谢谢。