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，单元格应展开到不同的高度并显示底层内容。

我的第一个实现有一个自定义 UICollectionViewCell，可以通过点击顶部按钮展开，但 collectionview 也不会展开。自动取款机。该单元格是集合视图中的最后一个单元格，只需向下滑动足够多的时间，您就可以看到展开的内容。如果您停止触摸，则滚动视图会向上跳跃，并且无法看到展开的单元格。

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
    })
  }
}

我也无法正确实现以下方法，因为我没有直接引用单元格：

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

基本上所有东西都应该是动画的。

屏幕截图显示了一个展开而不是展开的单元格。希望对您有所帮助！

谢谢！

Answer 1

如果在集合视图单元格内触摸按钮时需要将多个单元格扩展到不同的高度，那么，这里是代码。

我已经使用委托模式让控制器知道，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（ViewController），它会相应地更新 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)
        }
    }
}

查看控制器类

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")
        })
    }
}

Answer 2

不要直接更改单元格框架。实现func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize 并在那里处理高度。

假设您的 collectionView 中有一个单元格，其上方有一个顶部按钮：

let expanded = false

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize{
if expanded{
   // what is the size of the expanded cell?
   return collectionView.frame.size 
}else{
    // what is the size of the collapsed cell?
   return CGSizeZero
}
}

@IBAction func didTouchUpInsideTopButton(sender: AnyObject){
    // top button tap handler
    self.expanded = !self.expanded
    // this call will reload the cell and make it redraw (animated) Since the expanded flag changed, the sizeForItemAt call above will return a different size and animate the size change
    self.collectionView.reloadItemsAtIndexPaths([NSIndexPath(forRow: 0, inSection: 0)])
}

Answer 3

您可以使用标题来显示非展开单元格。当你在其中两个按钮或其他东西时，你可以将其他部分（扩展部分）作为一行插入到标题所属的部分中。

好处 - 展开时您可以使用许多提供的动画。