如何快速获取 UICollectionView 中的单元格 atIndex? [英] How to get cell atIndex in UICollectionView with swift?

问题描述

我正在以编程方式制作集合视图.这是 viewDidLoad func 中的代码

I am making Collection view programatically. Here is the code in viewDidLoad func

let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
    layout.sectionInset = UIEdgeInsets(top: 20, left: 20, bottom: 20, right: 20)
    layout.itemSize = CGSize(width: 90, height: 120)
    collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
    collectionView!.dataSource = self
    collectionView!.delegate = self
    collectionView!.registerClass(CollectionViewCell.self, forCellWithReuseIdentifier: "CollectionViewCell")
    collectionView!.layer.cornerRadius = 2
    collectionView!.backgroundColor = UIColor.redColor()
    self.containerView.addSubview(collectionView!)

这些是我的收藏视图函数

And these are my collection view functions

func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    return 1
}

func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return 8
}

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("CollectionViewCell", forIndexPath: indexPath) as! CollectionViewCell
    cell.backgroundColor = UIColor.blackColor()
    cell.buttonView.addTarget(self, action: Selector("Action(indexPath.row):"), forControlEvents: UIControlEvents.TouchUpInside)
    return cell
}

我的想法是我在单元格中有一个按钮，当我按下它时，单元格应该会改变颜色，这是动作函数

Idea is I have a button in the cell, and when I press it the cell should change color, here is the action function

func Action0(sender: UIButton!) {
    var indexPath = NSIndexPath(forRow: 0, inSection: 0)
    let cell = collectionView!.dequeueReusableCellWithReuseIdentifier("CollectionViewCell", forIndexPath: indexPath ) as! CollectionViewCell
    cell.backgroundColor = UIColor.blueColor()

这是 collectionViewCell 类，

and this is collectionViewCell class,

class CollectionViewCell: UICollectionViewCell {

required init(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}

var buttonView: UIButton!
override init(frame: CGRect) {
    super.init(frame: frame)

    buttonView = UIButton.buttonWithType(UIButtonType.System) as! UIButton
    buttonView.frame = CGRect(x: 0, y: 16, width: frame.size.width, height: frame.size.height*2/3)

    contentView.addSubview(buttonView)
}

}

按钮和动作有效，但单元格没有改变颜色，我猜问题出在这一行

The button and the action works but the cell doesn't change colour, i guess the problem is in this line

let cell = collectionView!.dequeueReusableCellWithReuseIdentifier("CollectionViewCell", forIndexPath: indexPath ) as! CollectionViewCell

推荐答案

这是获取给定 indexPath 处的单元格的方法:

This is the way to get the cell at a given indexPath:

let cell = collectionView!.cellForItemAtIndexPath(indexPath)

不过，你也可以试试:

cell.contentView.backgroundColor = UIColor.blueColor()

注意:

尽管上述方法可能有效，但我还是想鼓励您尝试不同的实现来实现相同的功能.您的实现将要求您为每个 CollectionViewCell 有一个单独的 Action# 函数，并在每个方法中手动创建 indexPath，而您可能只有一个！

Though the above may have worked, I want to encourage you to try a different implementation to achieve the same functionality. Your implementation would require you to have a separate Action# function for each CollectionViewCell, as well as create the indexPath manually in each of those methods, when you could potentially only have one!

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("CollectionViewCell", forIndexPath: indexPath) as! CollectionViewCell
    cell.backgroundColor = UIColor.blackColor()
    cell.buttonView.addTarget(self, action: Selector("action"), forControlEvents: UIControlEvents.TouchUpInside)
    return cell
}

并且该方法的 函数 类似于:

and the function for that one method would be something like:

func action(sender: UIButton!) {
    var point : CGPoint = sender.convertPoint(CGPointZero, toView:collectionView)
    var indexPath = collectionView!.indexPathForItemAtPoint(point)
    let cell = collectionView!.cellForItemAtIndexPath(indexPath)
    cell.backgroundColor = UIColor.blueColor()
}

为 Swift 4.2 更新了动作函数

@objc func action(sender: Any){
    print("tickedOffPressed !")
    if let button = sender as? UIButton {
        let point: CGPoint = button.convert(.zero, to: collectionView)
        if let indexPath = collectionView!.indexPathForItem(at: point) {
            let cell = collectionView!.cellForItem(at: indexPath)
            cell?.backgroundColor = UIColor.blue
        }
    }
}

只是一个建议！快乐编码！:)

Just a suggestion! Happy coding! :)

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