ios - 可扩展的 UICollectionViewCell

Question

我正在尝试编写一个可扩展的 UICollectionViewCell。 如果用户按下顶部按钮，单元格应扩展到不同的高度并显示下面的内容。

我的第一个实现有一个自定义的 UICollectionViewCell，可以通过单击顶部按钮展开，但 Collection View 不会展开。大气压该单元格是 collectionview 中的最后一个单元格，只需向下滑动足够多，您就可以看到展开的内容。如果你停止触摸，scrollview 会跳起来，展开的单元格什么都看不到。

这是我的代码:

import Foundation
import UIKit

class ExpandableCell: UICollectionViewCell {

  @IBOutlet weak var topButton: IconButton!

  public var expanded : Bool = false

  private var expandedHeight : CGFloat = 200

  private var notExpandedHeight : CGFloat = 50

  @IBAction func topButtonTouched(_ sender: AnyObject) {
    if (expanded == true) {
      self.deExpand()
    } else {
      self.expand()
    }
  }

  public func expand() {
   UIView.animate(withDuration: 0.8, delay: 0.0, usingSpringWithDamping: 0.9, initialSpringVelocity: 0.9, options: UIViewAnimationOptions.curveEaseInOut, animations: {
      self.frame = CGRect(x: self.frame.origin.x, y: self.frame.origin.y, width: self.frame.size.width, height: self.expandedHeight)
    }, completion: { success in
      self.expanded = true
    })
  }

  public func deExpand() {
    UIView.animate(withDuration: 0.8, delay: 0.0, usingSpringWithDamping: 0.9, initialSpringVelocity: 0.9, options: UIViewAnimationOptions.curveEaseInOut, animations: {
      self.frame = CGRect(x: self.frame.origin.x, y: self.frame.origin.y, width: self.frame.size.width, height: self.notExpandedHeight)
    }, completion: { success in
      self.expanded = false
    })
  }
}

我在正确实现以下方法时也遇到了问题，因为我没有直接引用该单元格:

 func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize

基本上一切都应该是动画的。

屏幕截图显示了展开和未展开的单元格。希望对您有所帮助!

谢谢!

Answer 1

如果您有多个单元格需要在 Collection View 单元格内触摸按钮时扩展到不同的高度，那么，这里是代码。

我使用委托(delegate)模式让 Controller 知道使用 indexPath 触摸了哪个单元格的按钮。 创建cell时需要将cell的indexpath传递给cell。

当按钮被触摸时，单元格调用委托(delegate)(ViewController)，它相应地更新 isExpandedArray 并重新加载特定的单元格。

CollectionViewCell

 protocol ExpandedCellDelegate:NSObjectProtocol{
    func topButtonTouched(indexPath:IndexPath)
}

class ExpandableCell: UICollectionViewCell {

    @IBOutlet weak var topButton: UIButton!
    weak var delegate:ExpandedCellDelegate?

    public var indexPath:IndexPath!

    @IBAction func topButtonTouched(_ sender: UIButton) {
        if let delegate = self.delegate{
            delegate.topButtonTouched(indexPath: indexPath)
        }
    }
}

View Controller Class

class ViewController: UIViewController {

    @IBOutlet weak var collectionView: UICollectionView!
    var expandedCellIdentifier = "ExpandableCell"

    var cellWidth:CGFloat{
        return collectionView.frame.size.width
    }
     var expandedHeight : CGFloat = 200
     var notExpandedHeight : CGFloat = 50

     var dataSource = ["data0","data1","data2","data3","data4"]
     var isExpanded = [Bool]()

    override func viewDidLoad() {
        super.viewDidLoad()
        isExpanded = Array(repeating: false, count: dataSource.count)
    }
}


extension ViewController:UICollectionViewDataSource{
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return dataSource.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
          let cell = collectionView.dequeueReusableCell(withReuseIdentifier: expandedCellIdentifier, for: indexPath) as! ExpandableCell
            cell.indexPath = indexPath
            cell.delegate = self
            //configure Cell
            return cell

    }
}

extension ViewController:UICollectionViewDelegateFlowLayout{
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

        if isExpanded[indexPath.row] == true{
             return CGSize(width: cellWidth, height: expandedHeight)
        }else{
            return CGSize(width: cellWidth, height: notExpandedHeight)
        }

    }

}

extension ViewController:ExpandedCellDelegate{
    func topButtonTouched(indexPath: IndexPath) {
        isExpanded[indexPath.row] = !isExpanded[indexPath.row]
        UIView.animate(withDuration: 0.8, delay: 0.0, usingSpringWithDamping: 0.9, initialSpringVelocity: 0.9, options: UIViewAnimationOptions.curveEaseInOut, animations: {
              self.collectionView.reloadItems(at: [indexPath])
            }, completion: { success in
                print("success")
        })
    }
}