Swiftコレクションビューで中央のセルを取得し、スクロール時にサイズを変更するにはどうすればよいですか？

Question

私は水平のcollectionViewを持っています。私はそれをスクロールするときに中央のセルが大きくなるように管理したいと思います。したがって、セルが中心セルになるたびに、他のセルよりも大きくなります。下の画像を確認してください。

これを行う最善の方法を教えてもらえますか？前もって感謝します！これまで

マイコード：

import UIKit 

class ViewController: UIViewController, UICollectionViewDataSource,  UICollectionViewDelegate { 
@IBOutlet var horizontalCollectionView: UICollectionView! 
@IBOutlet var verticalCollectionView: UICollectionView! 

var horizontal = ["1","2","3","4","5","6","7","8","9","10","1","2","3","4","5","6","7","8","9","10"] 
var horizontalCellSize = CGSize(width: 50, height: 50) 
var horizontalLargeCellSize = CGSize(width: 80, height: 80) 


var centerCell = UICollectionViewCell() 
var cellIsInCenter = false 
var myIndexPath = IndexPath() 

override func viewDidLoad() { 
    super.viewDidLoad() 

} 

// When the main view's dimensions change this will re-layout the collection view 
override func viewWillLayoutSubviews() { 
    verticalCollectionView.collectionViewLayout.invalidateLayout() 
} 

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int { 
    return horizontal.count 
} 

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell { 

    if collectionView == horizontalCollectionView { 
     let horizontalCell = collectionView.dequeueReusableCell(withReuseIdentifier: "HorizontalCell", for: indexPath) as! HorizontalCell 
     horizontalCell.backgroundColor = UIColor.blue 
     horizontalCell.textLabel.text = horizontal[indexPath.row] 
     return horizontalCell 
    } 

    else { 

     let verticalCell = collectionView.dequeueReusableCell(withReuseIdentifier: "VerticalCell", for: indexPath) as! VerticalCell 
     verticalCell.backgroundColor = UIColor.red 
     verticalCell.textLabel.text = horizontal[indexPath.row] 
     return verticalCell 
    } 
} 

// MARK: UIScrollViewDelegate 

func scrollViewDidScroll(_ scrollView: UIScrollView) { 
    if scrollView == self.horizontalCollectionView { 
     let horizontalScrollPosition = scrollView.contentOffset.x * 35 
     self.verticalCollectionView.delegate = nil 
     self.verticalCollectionView.contentOffset = CGPoint(x: 0, y: horizontalScrollPosition) 
     self.verticalCollectionView.delegate = self 
    } 

    if scrollView == self.verticalCollectionView { 
     let verticalScrollPosition = scrollView.contentOffset.y 
     self.horizontalCollectionView.delegate = nil 
     self.horizontalCollectionView.contentOffset = CGPoint(x: verticalScrollPosition, y: 0) 
     self.horizontalCollectionView.delegate = self 
    } 
} 


// MARK: CollectionViewLayout 

func collectionView(_ collectionView: UICollectionView, 
        layout collectionViewLayout: UICollectionViewLayout, 
        sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize { 
    if collectionView == verticalCollectionView { 
     let size = CGSize(width: collectionView.bounds.width, height: collectionView.bounds.height) 

     return size 
    } 

    if indexPath.item == 3 { 
     return CGSize(width: 70, height: 70) 
    } 
    return CGSize(width: 50, height: 50) 

} 

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) { 
    self.verticalCollectionView.scrollToItem(at: indexPath, at: .centeredVertically, animated: true) 
    print("\(indexPath)") 
} 

func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) { 
    var closestCell: UICollectionViewCell = self.horizontalCollectionView.visibleCells[0] 
    for cell in self.horizontalCollectionView.visibleCells as [UICollectionViewCell] { 
     let closestCellDelta = abs(closestCell.center.x - self.horizontalCollectionView.bounds.size.width/2.0 - self.horizontalCollectionView.contentOffset.x) 
     let cellDelta = abs(cell.center.x - self.horizontalCollectionView.bounds.size.width/2.0 - self.horizontalCollectionView.contentOffset.x) 
     if (cellDelta < closestCellDelta){ 
      closestCell = cell 
      self.centerCell = cell 
      self.cellIsInCenter = true 
      horizontalCellSize = CGSize(width: 80, height: 50) 
     } 
    } 
    let indexPath = self.horizontalCollectionView.indexPath(for: closestCell) 
    self.horizontalCollectionView.scrollToItem(at: indexPath!, at: .centeredHorizontally , animated: true) 
    if closestCell.backgroundColor == UIColor.black { 
     closestCell.backgroundColor = UIColor.blue 
    } 
    horizontalCollectionView.reloadItems(at: [self.horizontalCollectionView.indexPath(for: closestCell)!]) 
    closestCell.backgroundColor = UIColor.black 
} 
} 

Answer 1

はこれを試してみてください：このコードは、あなたのコレクションビューの中心にあるアイテムのインデックスを与える

func collectionView(_ collectionView: UICollectionView,layout collectionViewLayout: UICollectionViewLayout, 
sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize { 
if collectionView == verticalCollectionView { 
let size = CGSize(width: collectionView.bounds.width, height: collectionView.bounds.height) 
     return size 
    } 
let point = CGPoint(x: self.view.frame.size.width/2.0, y:35) 
//or you can try this code also 
//let point = CGPoint(x: UIScreen.main.bounds.width/2, y:35) 
    print(point) 
let centerIndex = self.collectionView.indexPathForItemAtPoint(point) 
    if indexPath.item == centerIndex { 
     return CGSize(width: 70, height: 70) 
    } 
    return CGSize(width: 50, height: 50) 
} 

。 欲しいものは