添加＆＃34;添加新＆＃34; UICollectionCell的最后一个单元格中的按钮。 （CoreData）

Question

尝试以不同的方式解决此问题。 当前的实现给了我一个错误：＆＃39; NSInvalidArgumentException＆＃39;，原因：＆＃39;索引0处的索引3处没有对象＆＃39; 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

你可以这样写它以使两个单独的单元格出列：

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")
    }
}

Answer 2

不要通过添加视图来破坏您的单元格。当细胞离开屏幕时细胞会被回收（这就是为什么它被称为dequeueReusableCell）。除非你在准备重用时删除了额外的视图，否则它们会留在单元格中并重新添加。相反，您还有其他两个选择：

1）在接口构建器中使用自己的类和reuseIdentifier创建第二个collectionViewCell，并仅为最后一个单元格取消此单元格的实例。

2）使按钮成为页脚视图的一部分并在viewForSupplementaryElementOfKind

中返回

Answer 3

这就是我的解决方法：迅速4.2

 func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
       // +1 here for the extra add button
        // bottom of the collection view
        return item.count + 1
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        //initialization cell
        let cells : UICollectionViewCell?

        if indexPath.row < item.count {

         // if indexpath.row < item.count => assign value to cellPet 

            let cellPet = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell1", for: indexPath) as! CollectionViewCell1
          // setup data cell  or not
            cellPet.setupView(listPet: item[indexPath.row ])

          // assign values c​​ells
            cells = cellPet

        } else {
            // assign value to cellAdd 
            let cellAdd = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell2", for: indexPath) as! CollectionViewCell2
            // setup data cell or not setup

            // assign values c​​ells
            cells = cellAdd
        }
        return cells!
    }

Answer 4

你可以这样做

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell", for: indexPath) as! CollectionViewCell
    if indexPath.row < myArr.count {
        cell.configure(with: CollectionModelViewCell(label: myArr[indexPath.row].text))
    } else {
        cell.configure(with: CollectionModelViewCell(label: "+"))
    }
    return cell
}