ios - 为什么未显示 Collection Reusable View？

Question

我想创建带标题的 UICollectionView。我在 mainStoryBoard 上设置了 Collection Reusable View，但是设备上没有显示任何内容。我试图搜索但无法找出它没有出现的原因。我

主要 Storyboard

在设备上

导入 UIKit

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {


    @IBOutlet weak var collectionView: UICollectionView!

    var images = ["medal1","medal2","medal3","medal4","medal5","medal6","medal7","medal8","medal9","medal10","medal1","medal2","medal3","medal14"]

    var texts = ["hi","yes","hoo","such","hi","yes","hoo","such","hi","yes","hoo","such","hi","yes"]

    override func viewDidLoad() {
        super.viewDidLoad()



        collectionView.delegate = self
        collectionView.dataSource = self

    }

    public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

        return images.count
    }

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

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CustomCell", for: indexPath) as! CustomCell

        cell.myImage.image = UIImage(named: images[indexPath.row])

        cell.achievementLabel.text = texts[indexPath.row]

        return cell

    }

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






}


import UIKit

Collection View 类 CustomCell 类:UICollectionViewCell {

    @IBOutlet weak var myImage: UIImageView!

    @IBOutlet weak var achievementLabel: UILabel!

}

集合可重用 View 类 导入 UIKit

class CollectionReusableView: UICollectionReusableView {

    @IBOutlet weak var reuseableVimage: UIImageView!
}


> import UIKit

class ViewController: UIViewController, UICollectionViewDelegate {


    @IBOutlet weak var collectionView: UICollectionView!

    var images = ["medal1","medal2","medal3","medal4","medal5","medal6","medal7","medal8","medal9","medal10","medal1","medal2","medal3","medal14"]

    var texts = ["hi","yes","hoo","such","hi","yes","hoo","such","hi","yes","hoo","such","hi","yes"]

    override func viewDidLoad() {
        super.viewDidLoad()



        collectionView.delegate = self


    }

    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        if kind == UICollectionElementKindSectionHeader {
            let view = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "HeaderView", for: indexPath)
            // do any programmatic customization, if any, here
            return view
        }
        fatalError("Unexpected kind")








}
}

Answer 1

您必须实现 viewForSupplementaryElementOfKind:

1. 实现 collectionView(_:viewForSupplementaryElementOfKind:at:) ，适用于 UICollectionElementKindSectionHeader 或 UICollectionElementKindSectionFooter。

   func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
       if kind == UICollectionElementKindSectionHeader {
           let view = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "CollectionReusableView", for: indexPath) as! CollectionReusableView
           // do any programmatic customization, if any, here
           return view
       }
       fatalError("Unexpected kind")
   }
   

2. 确保 IB 中的标题可重用 View 有

   • 适当的基类；和
   • 适当的“重用标识符”

3. 在 IB 中，确保 Collection View 的“附件”在“节页眉”和“节页脚”旁边有适当的复选标记。