我已经创建了自定义集合视图布局（用于多向滚动），运行成功。现在，我试图从各个方面（顶部，左侧，右侧和底部）实现分页。为此，我正在跟踪滚动方向，并在到达边界元素时，我希望在该方向上分页（加载更多数据）。但由于我需要将页面默认设置为左上角位置，因此已经到达左上角的元素，从而导致冲突。你能帮忙吗？
我试过以下代码：
import UIKit
class ViewController: UIViewController{
var cellId: String = "MyCellId"
var vPivotPrev = 0
var vPivotNext = 19
var hPivotPrev = 0
var hPivotNext = 29
var targetPoint = CGPoint(x: 0, y: 0)
var scrollDirection: String = ""
var scrolledDailyToTop:String = ""
var scrolledDailyToBottom:String = ""
var scrolledDailyToLeft:String = ""
var scrolledDailyToRight:String = ""
var shouldPaginate:Bool = false
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
showCollectionView()
}
var customCollectionView: UICollectionView = { // CODE TO CREATE CUSTOM COLLECTION VIEW
let layout = CustomCollectionViewLayout()
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
return cv
}()
class CustomCell: UICollectionViewCell{ // CODE TO CREATE CUSTOM CELLS
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)!
setup()
}
override init(frame: CGRect) {
super.init(frame: frame)
setup()
}
let label: UILabel = {
let myLabel = UILabel()
return myLabel
}()
func setup(){
addSubview(label)
}
}
func showCollectionView(){
view.addSubview(customCollectionView)
customCollectionView.backgroundColor = .darkGray
customCollectionView.frame = CGRect(x: 60, y: 145, width: UIScreen.main.bounds.size.width-120, height: UIScreen.main.bounds.size.height/1.8)
customCollectionView.dataSource = self
customCollectionView.delegate = self
customCollectionView.register(CustomCell.self, forCellWithReuseIdentifier: cellId) // REGISTER CELL CLASS
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
// DETECT SCROLL DIRECTION CODE
var currentPoint = scrollView.contentOffset
if(targetPoint.y > currentPoint.y){
scrollDirection = "going up"
print(scrollDirection)
}
else if(targetPoint.y < currentPoint.y){
scrollDirection = "going down"
print(scrollDirection)
}
if(targetPoint.x > currentPoint.x){
scrollDirection = "going left"
print(scrollDirection)
}
else if(targetPoint.x < currentPoint.x){
scrollDirection = "going right"
print(scrollDirection)
}
self.targetPoint = scrollView.contentOffset
}
}
extension ViewController: UICollectionViewDataSource{
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 20
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 30
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! CustomCell
cell.label.text = "\(indexPath.section.description),\(indexPath.item.description)"
cell.backgroundColor = .lightGray
cell.label.frame = CGRect(x: 0, y: 0, width: cell.contentView.bounds.width, height: 10)
cell.label.textColor = .white
cell.bringSubview(toFront: cell.label)
return cell
}
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
for visibleIndices in collectionView.indexPathsForVisibleItems{
if(visibleIndices.section == vPivotPrev){
scrolledDailyToTop = "top"
shouldPaginate = true
paginate()
}
else if(visibleIndices.section == vPivotNext){
scrolledDailyToBottom = "bottom"
shouldPaginate = true
paginate()
}
else if(visibleIndices.item == hPivotPrev){
scrolledDailyToLeft = "left"
shouldPaginate = true
paginate()
}
else if(visibleIndices.item == hPivotNext){
scrolledDailyToRight = "right"
shouldPaginate = true
paginate()
}
}
}
func paginate(){
print("Swipe Direction: \(scrollDirection)")
if(shouldPaginate == true){
if(self.scrollDirection == "going down" && self.scrolledDailyToTop == "top"){ // PAGINATING USING 9 BOX LOGIC
print("Fetch Vertical previous page")
//getNewPageData(gotopageURL: self.goToPageURL)
self.customCollectionView.scrollToItem(at: IndexPath(row: 0, section: 0), at: .bottom, animated: false)
self.customCollectionView.scrollToItem(at: IndexPath(row: 0, section: 0), at: .left, animated: false)
shouldPaginate = false
}
else if(self.scrollDirection == "going up" && self.scrolledDailyToBottom == "bottom"){
print("Fetch Vertical next page")
//getNewPageData(gotopageURL: self.goToPageURL)
self.customCollectionView.scrollToItem(at: IndexPath(row: 0, section: 0), at: .top, animated: false)
self.customCollectionView.scrollToItem(at: IndexPath(row: 0, section: 0), at: .left, animated: false)
shouldPaginate = false
}
else if(self.scrollDirection == "going right" && self.scrolledDailyToLeft == "left"){
print("Fetch Horizontal previous page")
//getNewPageData(gotopageURL: self.goToPageURL)
self.customCollectionView.scrollToItem(at: IndexPath(row: 0, section: 0), at: .top, animated: false)
self.customCollectionView.scrollToItem(at: IndexPath(row: 0, section: 0), at: .right, animated: false)
shouldPaginate = false
}
else if(self.scrollDirection == "going left" && self.scrolledDailyToRight == "right"){
print("Fetch Horizontal next page")
//getNewPageData(gotopageURL: self.goToPageURL)
self.customCollectionView.scrollToItem(at: IndexPath(row: 0, section: 0), at: .top, animated: false)
self.customCollectionView.scrollToItem(at: IndexPath(row: 0, section: 0), at: .left, animated: false)
shouldPaginate = false
}
scrolledDailyToTop = ""
scrolledDailyToBottom = ""
scrolledDailyToLeft = ""
scrolledDailyToRight = ""
}
}
}
extension ViewController: UICollectionViewDelegate{
func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
let cell:CustomCell = collectionView.cellForItem(at: indexPath)! as! ViewController.CustomCell
print("SELECTED CELL: \(cell.label.text!)")
return true
}
}
Multi-Directional Scroll CustomCollectionViewLayout
的代码import UIKit
class CustomCollectionViewLayout:UICollectionViewFlowLayout {
let CELL_HEIGHT = 50.0
let CELL_WIDTH = 80.0
let STATUS_BAR = UIApplication.shared.statusBarFrame.height
var cellAttrsDictionary = Dictionary<IndexPath, UICollectionViewLayoutAttributes>()
var contentSize = CGSize.zero
var dataSourceDidUpdate = true
override var collectionViewContentSize : CGSize {
return self.contentSize
}
override func prepare() {
dataSourceDidUpdate = false
cellAttrsDictionary.removeAll()
if let sectionCount = collectionView?.numberOfSections, sectionCount > 0 {
for section in 0...sectionCount-1 {
if let rowCount = collectionView?.numberOfItems(inSection: section), rowCount > 0 {
for item in 0...rowCount-1 {
let cellIndex = IndexPath(item: item, section: section)
let xPos = Double(item) * CELL_WIDTH
let yPos = Double(section) * CELL_HEIGHT
let cellAttributes = UICollectionViewLayoutAttributes(forCellWith: cellIndex)
cellAttributes.frame = CGRect(x: xPos, y: yPos, width: CELL_WIDTH, height: CELL_HEIGHT)
if section == 0 && item == 0 {
cellAttributes.zIndex = 4
} else if section == 0 {
cellAttributes.zIndex = 3
} else if item == 0 {
cellAttributes.zIndex = 2
} else {
cellAttributes.zIndex = 1
}
cellAttrsDictionary[cellIndex] = cellAttributes
}
}
}
}
let contentWidth = Double(collectionView!.numberOfItems(inSection: 0)) * CELL_WIDTH
let contentHeight = Double(collectionView!.numberOfSections) * CELL_HEIGHT
self.contentSize = CGSize(width: contentWidth, height: contentHeight)
}
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
var attributesInRect = [UICollectionViewLayoutAttributes]()
for cellAttributes in cellAttrsDictionary.values {
if rect.intersects(cellAttributes.frame) {
attributesInRect.append(cellAttributes)
}
}
return attributesInRect
}
override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
return cellAttrsDictionary[indexPath]!
}
override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
return true
}
}