在 UICollectionCell 的最后一个单元格中添加“添加新”按钮。（核心数据）

Question

尝试从不同的方式解决这个问题。当前的实现给了我一个错误：“NSInvalidArgumentException”，原因：“索引 0 部分中索引 3 处没有对象”它发生在 AppDelegate 类：UIResponder...

我的代码是

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

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! CollectionCell
    configureCell(cell: cell, indexPath: indexPath)

    var numberOfItems = self.collectionView(self.collectionView, numberOfItemsInSection: 0)

    if (indexPath.row == numberOfItems - 1) {

        var addCellButton = UIButton(frame: cell.frame)
        addCellButton.setTitle("Add", for: UIControlState.normal)
        cell.addSubview(addCellButton)
    } 
    return cell
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

    if let sections = controller.sections {
        let sectionInfo = sections[section]
        return sectionInfo.numberOfObjects + 1
    }
    return 0
}

func numberOfSections(in collectionView: UICollectionView) -> Int {
    if let sections = controller.sections {
        return sections.count
    }
    return 0
}

有什么建议吗？

Answer 1

您可以像这样编写它来使两个单独的单元出队：

import UIKit

class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {

    var collectionView:UICollectionView!
    var items = ["Apple", "Banana", "Orange", "Watermelon", "Coconut"]


    ...

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

        // ------------------------------------------
        // +1 here for the extra add button
        // at the bottom of the collection view
        // ------------------------------------------
        return items.count + 1
    }

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

        // --------------------------------
        // IndexPath row vs Items Count
        // --------------------------------
        // [0] = Apple
        // [1] = Banana
        // [2] = Orange
        // [3] = Watermelon
        // [4] = Coconut
        //
        // [5] = special cell
        //
        // ---------------------------------
        let cellID = indexPath.row < items.count ? "normalCell" : "specialCell"

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellID, for: indexPath)

        setupCell(cell: cell, indexPath: indexPath, type: cellID)

        return cell
    }

    func setupCell(cell: UICollectionViewCell, indexPath: IndexPath, type: String) {
        switch(type) {
        case "normalCell":
            setupFruitCell(cell: cell as! FruitCell, indexPath: indexPath)
        case "specialCell":
            setupSpecialCell(cell: cell as! SpecialCell, indexPath: indexPath)
        default:
            break
        }
    }

    func setupFruitCell(cell: FruitCell, indexPath: IndexPath) {
        cell.label.text = items[indexPath.row]
    }

    func setupSpecialCell(cell: SpecialCell, indexPath: IndexPath) {
        cell.btnAdd.addTarget(self, action: #selector(addButtonTapped), for: UIControlEvents.touchUpInside)
    }

    func addButtonTapped(sender: UIButton) {
        print("Show UI to add new fruit")
    }
}