更改收集视图的`numberOfitemSinsection`参数

Question

如何更改集合视图的numberOfitemSinsection参数？

我已经对收集视图进行了基本设置。现在，我尝试制作一个按钮，以更改其中的项目数量。

常规设置是标准设置：

   func numberOfSections(in collectionView: UICollectionView) -> Int {
        1
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        arrayA.count
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CollectionViewCell            
        cell.imageView.image = arrayA[indexPath.item][0].image
        return cell
    }

问题是 - 如何配置一个按钮，因此它可以从当前arraya.count.count.count更改numberFitemSinsection参数（ex arrayb.count ）？

示例：

Answer 1

您可以将通用的标志带在arraya和arrayb之间切换。单击按钮时

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return isUseArrayA ? arrayA.count : arrayB.count
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CollectionViewCell           
    cell.imageView.image = isUseArrayA ? arrayA[indexPath.item][0].image : arrayB[indexPath.item][0].image
    return cell
}

@IBAction func changeSource(sender: UIButton) {
    if sender.tag == 0 {
       isUseArrayA = true
       sender.tag = 1
    } else {
       sender.tag = 0
       isUseArrayA = false
    } 
    DispatchQueue.main.async { [weak self] in
        guard let self = self else { return }
        self.collectionView.reloadData()
    }
}

Answer 2

// No need of numberOfSection because it is bydefault 1.

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    arrayA.count
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CollectionViewCell
    cell.imageView.image = arrayA[indexPath.item][0].image
    return cell
}

@IBAction func changeArrayCount(sender: UIButton) {
    arrayA.append(image)
    DispatchQueue.main.async { [weak self] in
        guard let self = self else { return }
        self.collectionView.reloadData()
    }
}