我有两个不同的单元格类型类，我正试图用PayNowCell类创建第一个indexpath，让它保持显示。而其他单元格是类签出单元格。现在问题出在我的func numberofitems部分。当前我正在使用return checkout.count，但在加载视图时它缺少PayNowCell。如果我让它返回checkout.count+1以使PayNowCell始终可用；我的程序将崩溃，错误索引超出范围。数组签出是一个全局变量。有人能解释原因并提供修复吗？被困在这上面有一段时间了。代码如下。
class CheckoutController: UICollectionViewCell, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {
var inventoryTabController: InventoryTabController?
override init(frame: CGRect){
super.init(frame: frame)
setupViews()
NotificationCenter.default.addObserver(forName: .arrayValueChanged, object: nil, queue: OperationQueue.main) { [weak self] (notif) in
self?.collectionView.reloadData()
}
}
deinit {
NotificationCenter.default.removeObserver(self)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func loadItems() -> [Item]? {
return NSKeyedUnarchiver.unarchiveObject(withFile: Item.ArchiveURL.path) as? [Item]
}
func saveItems() {
let isSuccessfulSave = NSKeyedArchiver.archiveRootObject(checkout, toFile: Item.ArchiveURL.path)
if !isSuccessfulSave {
print("Failed to save items...")
}
}
func addItem(item: Item) {
items.append(item)
collectionView.reloadData()
}
func editItem(item: Item, index: Int) {
items[index] = item
collectionView.reloadData()
}
func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Identify which segue is occuring.
if segue.identifier == "ShowDetail" {
let itemDetailViewController = segue.destination as! AddItemController
// Get the cell that generated this segue.
if let selectedItemCell = sender as? InventoryCell {
let indexPath = collectionView.indexPath(for: selectedItemCell)!
let selectedItem = items[indexPath.row]
itemDetailViewController.item = selectedItem
}
}
else if segue.identifier == "AddItem" {
print("Adding new meal.")
}
}
lazy var collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
cv.dataSource = self
cv.delegate = self
cv.backgroundColor = UIColor.rgb(r: 247, g: 247, b: 247)
return cv
}()
let cellId = "cellId"
let paynow = "paynow"
func setupViews() {
backgroundColor = .brown
addSubview(collectionView)
addConstraintsWithFormat("H:|[v0]|", views: collectionView)
addConstraintsWithFormat("V:|[v0]|", views: collectionView)
collectionView.indicatorStyle = UIScrollViewIndicatorStyle.white
collectionView.register(PayNowCell.self, forCellWithReuseIdentifier: paynow)
collectionView.register(CheckoutCell.self, forCellWithReuseIdentifier: cellId)
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return checkout.count //init number of cells
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.item == 0 {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "paynow", for: indexPath) as! PayNowCell //init cells
return cell
}else{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath) as! CheckoutCell //init cells
print("Printing this \(checkout.count)")
cell.item = checkout[indexPath.item]
return cell
}
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
//let item = items[indexPath.item]
//inventoryController?.showItemDetailForItem(item: item, index: indexPath.item)
print("selected")
print(indexPath.item)
collectionView.reloadData()
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
if indexPath.item == 0 {
return CGSize(width:frame.width, height: 100) //each cell dimensions
}else{
return CGSize(width:frame.width, height: 150) //each cell dimensions
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
最佳答案
最好将集合视图重新排列为两个部分：
第0节：PayNow单元格（仅1个单元格）
第1节：签出单元格（使用签出数组列表）
那么您就不会对indexPath.item问题有任何混淆了。
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 2
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return section == 0 ? 1 : checkout.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.section == 0 {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "paynow", for: indexPath) as! PayNowCell //init cells
return cell
} else {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath) as! CheckoutCell //init cells
print("Printing this \(checkout.count)")
cell.item = checkout[indexPath.item]
return cell
}
}
关于ios - UICollection NumberOfItemsInSections问题向常量添加常量，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/41421205/