I have a horizontal collectionView and i would like to manage that when scrolling it, the centre cell becomes larger. So, each time a cell is the center cell it will be larger than the others. Check the image beneath.
谁能帮助我找到最好的方法来做到这一点？提前致谢！
到目前为止我的代码：
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
}
}
试试这个：
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)
}
此代码为您提供集合视图中心的项目的索引。 希望这可以帮助