ios - didSelectItemAtIndexPath 中的 cell.contentView.viewWithTag 与 cell.viewWithTag 的工作方式不同

Question

我的UICollectionView有一个UILabel和一个UIImageView，我认为它们并且工作得很好，如下所示:

 func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell{
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier("coffee_brand_cell", forIndexPath: indexPath) //as! AURCoffeeBrandCollectionViewCell
        let imageView = cell.contentView.viewWithTag(1) as? UIImageView

        imageView?.image = UIImage(named: ["coffee1","coffee2","coffee3","coffee3"][indexPath.row])
        let name = cell.contentView.viewWithTag(2) as? UILabel
        name?.text = coffeeName[indexPath.row] + String(indexPath.row)
        name?.textColor = UIColor(red: 226.0/255.0, green: 170.0/255.0, blue: 119.0/255.0, alpha: 1.0)
        name?.adjustsFontSizeToFitWidth = true
        cell.backgroundColor = collectionView.backgroundColor
        cell.layoutIfNeeded()
        imageView?.layer.cornerRadius = (cell.frame.width - 40)/2.0
        imageView?.layer.masksToBounds = true

        return cell
    }

但是我无法获取所选单元格的名称和图像，如下所示，

func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
           let cell = collectionView.cellForItemAtIndexPath(indexPath)
            if let name = cell?.contentView.viewWithTag(2) {
                //Can't get into this.
            }
    }
}

单元格的 contentView subview 返回 0。

cell!.contentView.subviews
0 elements

更新:

cell.contentView.viewWithTag(2) 适用于 cellForItemAtIndexPath，但不适用于 didSelectItemAtIndexPath。但是 cell.viewWithTag(2) 可以工作。

为什么 contentView 的工作方式不同？

更新

将这两行插入到 didSelectItemAtIndexPath

        print(" selected cell is \((cell?.viewWithTag(2) as! UILabel).text!)")
        print(" selected cell is \((cell?.contentView.viewWithTag(2) as! UILabel).text!)")

输出:

selected cell is Kii Kenya0
fatal error: unexpectedly found nil while unwrapping an Optional value

项目可以在这里下载:Link

PS:我检查了 contentView 的 subview 的“已安装”。 模拟器中的 CollectionView。

Answer 1

尝试使用这个

import UIKit

class CollectionUIViewController: UIViewController,UICollectionViewDataSource,UICollectionViewDelegate{

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }



    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
    {
        return 20
    }

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell
    {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier("customCellIdentifier", forIndexPath: indexPath)
        (cell.contentView.viewWithTag(1) as! UIImageView).image = UIImage(named: "Image")
        (cell.contentView.viewWithTag(2) as! UILabel).text = "cell no \(indexPath.row)"
        return cell
    }

    func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath)
    {
        let selectedCell = collectionView.cellForItemAtIndexPath(indexPath)
        print(" selected cell is \((selectedCell?.contentView.viewWithTag(2) as! UILabel).text!)")

    }



}

我通过使用 viewWithTag 访问所选单元格的标签文本(随附快照供引用)