ios - Swift - 切换 CollectionView 单元格以切换数组中的项目

Question

我有两个 CollectionView。一个 CollectionView (allHobbiesCV) 预先填充了您可以选择的兴趣爱好。另一个 CollectionView (myHobbiesCV) 是空的，但如果您在 allHobbiesCV 中点击一个爱好，它就会被添加到 myHobbiesCV 中。这一切都很好。

我希望点击的 allHobbiesCV 单元格切换到选中状态，它将爱好添加到 myHobbiesCV，然后如果用户在 allHobbiesCV 中再次点击相同的选定单元格，它会从 myHobbiesCV 中删除该爱好。基本上是一个切换添加/删除。

需要注意两点:

1. 用户可以在 myHobbiesCV 中手动选择爱好，然后点击 [删除爱好] 按钮。
2. Hobbies 将按季节排序，因此 allHobbiesArray 将有 4 个不同的数据集(冬季、 Spring 、夏季、秋季)。取决于用户点击的季节 (ViewController)。他们可以根据需要从每个单元格中选择任意数量的单元格。

问题:

除了第一个单元格之外，我在任何切换时都会崩溃。如果我选择 allHobbiesCV 中的第一个单元格，我可以再次选择它，它会将它从 myHobbiesCV 中删除。如果我再次选择同一个单元格(切换它)，我会崩溃。如果我选择第一个单元格以外的任何其他单元格，我会崩溃。

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'attempt to delete item 7 from section 0 which only contains 3 items before the update'

类(class)

// Winter Hobbies
let allHobbiesArray = ["Skiing", "Snowboarding", "Drinking Bourbon", "Snow Shoeing", "Snowmobiling", "Sledding", "Shoveling Snow", "Ice Skating"]
var myHobbiesArray = [String]()
var allSelected = [IndexPath]()
var didSelectIPArray = [IndexPath]()

数据源

extension ViewController: UICollectionViewDataSource {
func numberOfSections(in collectionView: UICollectionView) -> Int {
    return 1
}

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


    if collectionView == allHobbiesCV {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ALL", for: indexPath) as! AllHobbiesCell
        cell.allHobbiesLabel.text = allHobbiesArray[indexPath.item]

        if cell.isSelected {
            cell.backgroundColor = UIColor.green
        }
        else {
            cell.backgroundColor = UIColor.yellow
        }

        return cell
    }

    else {
        let cell = myHobbiesCV.dequeueReusableCell(withReuseIdentifier: "MY", for: indexPath) as! MyHobbiesCell
        cell.myHobbiesLabel.text = myHobbiesArray[indexPath.item]

        if cell.isSelected {
            cell.backgroundColor = UIColor.red
        }
        else {
            cell.backgroundColor = UIColor.yellow
        }


        return cell
    }


}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    if collectionView == allHobbiesCV {
        return allHobbiesArray.count
    }
    else {
        return myHobbiesArray.count
    }

}

}

委托(delegate)

extension ViewController: UICollectionViewDelegate {
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {


    if collectionView == allHobbiesCV {
        if myHobbiesArray.count <= 6
            self.allSelected = []

            didSelectIPArray.append(indexPath) // Store the selected indexPath in didSelectIPArray

            myHobbiesArray.insert(allHobbiesArray[indexPath.item], at: 0)
            let allHobbiesCell = allHobbiesCV.cellForItem(at: indexPath) as! AllHobbiesCell
            allHobbiesCell.backgroundColor = UIColor.green

            // Store all of the selected cells in an array
            didSelectIPArray.append(indexPath) 

            myHobbiesCV.reloadData()
        }
    }


    else {
        let cell = myHobbiesCV.cellForItem(at: indexPath) as! MyHobbiesCell
        cell.backgroundColor = UIColor.red
        allSelected = self.myHobbiesCV.indexPathsForSelectedItems!
    }


}

// Deselecting selected cells
func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {

    if collectionView == allHobbiesCV {

        // Yellow is the unselected cell color. So let's change it back to yellow.
        let allHobbiesCell = allHobbiesCV.cellForItem(at: indexPath) as! AllHobbiesCell
        allHobbiesCell.backgroundColor = UIColor.yellow

        // Remove (toggle) the cells. This is where I am stuck/crashing.
        let indices = didSelectIPArray.map{ $0.item }
        myHobbiesArray = myHobbiesArray.enumerated().flatMap { indices.contains($0.0) ? nil : $0.1 }
        self.myHobbiesCV.deleteItems(at: didSelectIPArray)

        myHobbiesCV.reloadData()

        didSelectIPArray.remove(at: indexPath.item) // Remove the deselected indexPath from didSelectIPArray
    }

    else { // MyHobbies CV
        let cell = myHobbiesCV.cellForItem(at: indexPath) as! MyHobbiesCell
        cell.backgroundColor = UIColor.yellow

        // Store the selected cells to be manually deleted.
        allSelected = self.myHobbiesCV.indexPathsForSelectedItems!

    }
}
}

删除按钮

@IBAction func deleteButtonPressed(_ sender: UIButton) {
    for item in didSelectIPArray {
        self.allHobbiesCV.deselectItem(at: item, animated: false) // Try deselecting the deleted items in allHobbiesCV... This is crashing.
    }
}

问题是我如何尝试在 didDeselect 中切换 allHobbiesCV 单元格。我在 didSelectIPArray 中保存所选单元格的方法是否正确？

如果需要，我很乐意提供进一步的见解。提前谢谢各位 friend !

Answer 1

不需要所有的 map 和 flatmap 东西。您可以简单地从选定的爱好数组中删除该对象:

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    if collectionView == allHobbiesCV {
        if myHobbiesArray.count <= 6
            self.allSelected = []
            myHobbiesArray.insert(allHobbiesArray[indexPath.item], at: 0)

            let allHobbiesCell = allHobbiesCV.cellForItem(at: indexPath) as! AllHobbiesCell
            allHobbiesCell.backgroundColor = UIColor.green

            myHobbiesCV.insertItems(at: [IndexPath(item: 0, section: 0)])
        }
    } else {
        let cell = myHobbiesCV.cellForItem(at: indexPath) as! MyHobbiesCell
        cell.backgroundColor = UIColor.red
        allSelected = self.myHobbiesCV.indexPathsForSelectedItems!
    }
}

func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {

    if collectionView == allHobbiesCV {

        // Yellow is the unselected cell color. So let's change it back to yellow.
        let allHobbiesCell = allHobbiesCV.cellForItem(at: indexPath) as! AllHobbiesCell
        allHobbiesCell.backgroundColor = UIColor.yellow

        let hobby = allHobbiesArray[indexPath.item]

        if let index = myHobbiesArray.index(of:hobby) {
             myHobbiesArray.remove(at: index)
             myHobbiesCV.deleteItems(at: [IndexPath(item: index, section:0)])
        }
    } else { // MyHobbies CV
        let cell = myHobbiesCV.cellForItem(at: indexPath) as! MyHobbiesCell
        cell.backgroundColor = UIColor.yellow

        // Store the selected cells to be manually deleted.
        allSelected = self.myHobbiesCV.indexPathsForSelectedItems!

    }
}