为什么未显示集合可重用视图？

Question

我想创建带有标题的 UICollectionView。我在 mainStoryBoard 上设置了 Collection Reusable View，但设备上没有显示任何内容。我试图搜索但找不到它为什么没有出现。我

主要故事板

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

集合视图类 类 CustomCell: UICollectionViewCell {

    @IBOutlet weak var myImage: UIImageView!

    @IBOutlet weak var achievementLabel: UILabel!

}

集合可重用视图的类 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

你必须实现viewForSupplementaryElementOfKind:

1. 针对UICollectionElementKindSectionHeader 或UICollectionElementKindSectionFooter 酌情实施collectionView(_:viewForSupplementaryElementOfKind:at:)。

   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 中的标题可重用视图具有

   • 适当的基类；和
   • 适当的“重用标识符”

3. 在 IB 中，确保集合视图的“附件”在“Section Header”和“Section Footer”旁边有复选标记。

Answer 2

尝试实现这一点。 RayWenderlich 中有一个可能对您有用的示例：https://www.raywenderlich.com/136161/uicollectionview-tutorial-reusable-views-selection-reordering

override func collectionView(_ collectionView: UICollectionView,
                             viewForSupplementaryElementOfKind kind: String,
                             at indexPath: IndexPath) -> UICollectionReusableView {
switch kind {
case UICollectionElementKindSectionHeader:
    let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind,
                                                                           withReuseIdentifier: "CollectionReusableView",
                                                                           for: indexPath) as! CollectionReusableView
    headerView.reuseableVimage ....
    return headerView
default:
    assert(false, "Unexpected element kind")
}
}