可扩展的UICollectionViewCell

时间:2016-11-26 22:50:02

标签: ios swift uicollectionview uicollectionviewcell

我正在尝试编写可扩展的UICollectionViewCell。 如果用户按下顶部按钮,则单元格应扩展到不同的高度并显示基础内容。

我的第一个实现具有自定义UICollectionViewCell,可以通过单击顶部按钮进行扩展,但collectionview也不会扩展。自动取款机。单元格是collectionview中的最后一个单元格,只需向下滑动,就可以看到展开的内容。如果你停止触摸,滚动视图会跳起来,看不到扩展单元格。

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,因为我还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。

屏幕截图显示了一个展开但未展开的单元格。希望有所帮助!

opened and closed cell

谢谢!

3 个答案:

答案 0 :(得分:17)

如果在集合视图单元格内触摸按钮时,有多个单元格需要扩展到不同的高度,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。 创建单元格时,需要将单元格的索引路径传递给单元格。

当触摸按钮时,单元格调用委托(ViewController),相应地更新isExpandedArray并重新加载特定单元格。

  

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")
        })
    }
}

答案 1 :(得分:1)

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

假设您在collectionView中有一个单元格,上面有一个顶部按钮:

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)])
}

答案 2 :(得分:0)

您可以使用标题显示非展开单元格。当您在其中有两个按钮或其他东西时,您可以在标题所属的那部分中将另一部分(扩展部分)作为一行插入。

优点-展开时,您可以使用许多提供的动画。