访问 UICollectionView 的父 UIViewController [英] Access a UICollectionView's parent UIViewController

问题描述

我的问题很简单.我有一个包含 UICollectionView 的 UIViewController.在初始化我的单元格时，我为每个单元格添加了一个手势识别器，这样当你点击并按住它时，它会调用一个带有选择器的函数.

My question is fairly straightforward. I have a UIViewController containing a UICollectionView. In initialising my cells, I add a gesture recogniser to each of them so that when you tap and hold it calls a function with a selector.

这个函数然后创建一个我想展示的 UIAlertController.(基本上，你拿着一个单元格，它会问你是否要删除它，如果你说是，它会从 CollectionView 中删除它)

This function then creates a UIAlertController which I want to present. (Basically, you hold a cell, it asks you if you want to delete it and if you say yes it eliminates it from the CollectionView)

问题是我无法从 UICollectionView 显示 UIAlertController，因为它不是 ViewController.

The problem is that I can't present a UIAlertController from my UICollectionView because it isn't a ViewController.

我想以编程方式获取包含 UICollectionView 的 UIViewController 以从 UICollectionView 实现中的函数显示此警报.

I want to programmatically get the UIViewController that contains the UICollectionView to present this alert from a function that is inside the UICollectionView implementation.

推荐答案

我通过在我的自定义 UICollectionViewCell 中创建一个协议并将这些事件委托回 UIViewController 来做到这一点，像这样

I do this by making a protocol in my custom UICollectionViewCell and delegate these events back to the UIViewController, something like this

在您的 MyCollectionViewCell

protocol MyCollectionViewCellDelegate: class {
    func didLongPressCell()
}

class MyCollectionViewCell:UICollectionViewCell {

    weak var delegate:MyCollectionViewCellDelegate?

    func longPressAction() {
        if let del = self.delegate {
            del.didLongPressCell
        }
    }

}

然后回到你的 MyViewController

class MyViewController:UIViewController, MyCollectionViewCellDelegate {

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath) as! MyCollectionViewCell
        cell.delegate = self
        return cell
    }

    func didLongPressCell() {
        // do what you want with the event from the cell here
    }

}

要记住的重要部分是为每个单元格设置委托

The important bits to remember are to set the delegate for each cell

cell.delegate = self

并在要接收事件的视图控制器中采用新协议

And adopt your new protocol in the view controller that you want to receive the events in

class MyViewController:UIViewController, MyCollectionViewCellDelegate

我还没有测试过这段代码，我不确定在像这样的每个单元格中存储对 viewController 的引用的最佳实践，但我做了一些非常相似的事情，让我知道你是怎么做的.

如果您已经将 UICollectionView 子类化，则将其传递给视图控制器的引用，以便您可以像这样使用它.

if you have subclassed your UICollectionView then pass it a reference to the view controller so that you can use it like so.

你的 MyViewController 现在看起来像这样

Your MyViewController would now look like this

class MyViewController:UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        let collectionView = MyCollectionView()
        collectionView.viewController = self
        self.view.addSubview(collectionView)
    }

}

以及您的自定义集合视图 MyCollectionView

class MyCollectionView:UICollectionView, MyCollectionViewCellDelegate {

    weak var viewController:UIViewController?

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath) as! MyCollectionViewCell
        cell.delegate = self
        return cell
    }

    func didLongPressCell() {
        if let vc = self.viewController {
            // make use of the reference to the view controller here
        }
    }

}

UICollectionViewCell 和之前一样

The UICollectionViewCell would be the same as before

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