如何从嵌套的collectionView单元格传递按钮操作？

Question

I have a MainCollectionView used for scrolling between items, inside of one of these cells I have another collectionView with cells. In that collection view, I have a button for each cell. My question is how do I pass action from my button to my MainCollectionView when it is tapped? I did create protocol for that button in the cell but I don't know how to let MainCollectionView know when my button is tapped. I can call action from my cell class but I think it is better to run it in Model which is my MainCollectionView. Below is my button protocol.

protocol ThanhCaHotTracksCellDelegate: class {
func handleSeeAllPressed()}

weak var delegate: ThanhCaHotTracksCellDelegate?


@objc func handleSeeAllButton(){
 delegate?.handleSeeAllPressed()
}

Answer 1

LIke NSAdi said, you're on the right track, but the delegate pattern is a bit much overhead for just a single task like notifying about a button press.

I prefer using closures, because they're lightweight and helps to keep related code together.

Using Closures

This is what I'm always doing in UITableView . So this will work in UICollectionView too.

class MyTableViewCell: UITableViewCell {
    var myButtonTapAction: ((MyTableViewCell) -> Void)?

    @IBAction func myButtonTapped(_ sender: Any) {
        myButtonTapAction?(self)
    }
}

So when I dequeue my cell and cast it to MyTableViewCell I can set a custom action like this:

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "myCellReuseIdentifier", for: indexPath) as! MyTableViewCell

    cell.myButtonTapAction = { cell in
        // Put your button action here
        // With cell you have a strong reference to your cell, in case you need it
    }
}

Using direct reference

When you're dequeueing your UICollectionView cell you can obtain a reference to your button by casting the cell to your cell's custom subclass.

Then just do the following

cell.button.addTarget(self, action: #selector(didTapButton(_:)), forControlEvents: .TouchUpInside)

And outside have a function:

@objc func didTapButton(_ sender: UIButton) {
    // Handle button tap
}

Downside of this is that you have no direct access to your cell. You could use button.superview? but it's not a good idea since your view hierarchy could change...

Answer 2

You're on the right track.

Make sure MainCollectionView (or the class that contains) it implements ThanhCaHotTracksCellDelegate protocol.

Then assign the delegate as self .

Something like...

class ViewController: ThanhCaHotTracksCellDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()

        subCollectionView.delegate = self
    }
}