How can I use switch statement to implement collec

问题:

I am new to swift and trying to implement collectionView function in a ViewController.Now I have three types of UICollectionViewCell,here is my code:

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

    if collectionView == self.collectionViewCategory {

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: categoryIdentifier, for: indexPath as IndexPath) as! CategoryCell

        cell.CategoryIcon.image = self.categoryItems[indexPath.item]
        cell.layer.borderColor = UIColor.lightGray.cgColor
        cell.layer.borderWidth = 1
        cell.layer.cornerRadius = 5

        return cell
    }
    else if collectionView == self.collectionViewHour {

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: hourIdentifier, for: indexPath as IndexPath) as! HourCell

        cell.hourItem.text = self.hourItems[indexPath.item]
        cell.layer.borderColor = UIColor.lightGray.cgColor
        cell.layer.borderWidth = 1
        cell.layer.cornerRadius = 5

        return cell
    }
    else {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: minuteIdentifier, for: indexPath as IndexPath) as! MinuteCell

        cell.minuteItem.text = self.minuteItems[indexPath.item]
        cell.layer.borderColor = UIColor.lightGray.cgColor
        cell.layer.borderWidth = 1
        cell.layer.cornerRadius = 5

        return cell
    }
}

Can I use switch statement to achieve the same effect?Make the code look a little more elegant?

I hope my code looks like this:

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

    let cell:UICollectionViewCell

    switch collectionView {
        case self.collectionViewCategory:
            cell = collectionView.dequeueReusableCell(withReuseIdentifier: categoryIdentifier, for: indexPath as IndexPath) as! CategoryCell
            cell.CategoryIcon.image = self.categoryItems[indexPath.item]
        case self.collectionViewHour:
            cell = collectionView.dequeueReusableCell(withReuseIdentifier: hourIdentifier, for: indexPath as IndexPath) as! HourCell
            cell.hourItem.text = self.hourItems[indexPath.item]
        default:
            //do nothing.
    }
    cell.layer.borderColor = UIColor.lightGray.cgColor
    cell.layer.borderWidth = 1
    cell.layer.cornerRadius = 5
    return cell
}

But I got a lot of mistakes, and I do not know how to fix them.

回答1:

Hope this help. Not testing at all. If any issues, can you take a snip ?

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

  let cell:UICollectionViewCell

  switch collectionView {
    case self.collectionViewCategory:
        let categoryCell = collectionView.dequeueReusableCell(withReuseIdentifier: categoryIdentifier, for: indexPath as IndexPath) as! CategoryCell
        categoryCell.CategoryIcon.image = self.categoryItems[indexPath.item]
        cell = categoryCell 
    case self.collectionViewHour:
        let hourCell = collectionView.dequeueReusableCell(withReuseIdentifier: hourIdentifier, for: indexPath as IndexPath) as! HourCell
        hourCell.hourItem.text = self.hourItems[indexPath.item]
        cell = hourCell
    default:
        //do nothing.
  }
  cell.layer.borderColor = UIColor.lightGray.cgColor
  cell.layer.borderWidth = 1
  cell.layer.cornerRadius = 5
  return cell

}

回答2:

You can try to assign each collectionView a unique tag like so

collectionView.tag = 1

and then use the tag as the identifier:

switch collectionView.tag {
    case 0:
        // some code
    case 1:
        // some code
    default:
        // some code
}

If you're using your collectionViews inside UITableViewCells you can set each collectionView.tag to be indexPath.section or indexPath.row within tableView(_ tableView: willDisplay cell: forRowAt indexPath:).

Here's a nice subclass you could use:

class CollectionViewTableViewCell: UITableViewCell {
    @IBOutlet weak var collectionView: UICollectionView!

    func setCollectionViewDataSourceDelegate(dataSource: UICollectionViewDataSource?, dataDelegate: UICollectionViewDelegate?, forSection section: Int) {

        collectionView.delegate = dataSource as! UICollectionViewDelegate?
        collectionView.dataSource = dataDelegate as! UICollectionViewDataSource?
        collectionView.tag = section
        collectionView.reloadData()
    }
}

and then in your view controller implement

override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
    guard let tableViewCell = cell as? CollectionViewTableViewCell else { return }
    tableViewCell.setCollectionViewDataSourceDelegate(dataSource: self, dataDelegate: self, forSection: indexPath.section)
}