iOS -在我的UICollectionViewCell上不应用自定义

Question

我正在使用堆叠在一个iOS中的一个StackLayout中的多个水平UICollectionViews来编程一个ScrollView应用程序。我想在这些集合视图中显示映像，但是我的自定义UICollectionViewCell没有显示任何内容。

以下是我正在做的事情

我跟踪了多个集合视图的本教程，以及自定义单元格的这一个。

这是我的ViewController：

import UIKit

struct CustomImage {
    var title: String
    var image: UIImage
}

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {

@IBOutlet weak var perspectiveCV: UICollectionView!
@IBOutlet weak var monkeyCV: UICollectionView!
@IBOutlet weak var beachCV: UICollectionView!

let perspectiveImages = [
    CustomImage(title: "Perspective 1", image: #imageLiteral(resourceName: "perspective-1")),
    CustomImage(title: "Perspective 2", image: #imageLiteral(resourceName: "perspective-2")),
    CustomImage(title: "Perspective 3", image: #imageLiteral(resourceName: "perspective-3")),
    CustomImage(title: "Perspective 4", image: #imageLiteral(resourceName: "perspective-4")),
    CustomImage(title: "Perspective 5", image: #imageLiteral(resourceName: "perspective-5")),
    CustomImage(title: "Perspective 6", image: #imageLiteral(resourceName: "perspective-6"))
]

let monkeyImages = [
    CustomImage(title: "Monkey 1", image: #imageLiteral(resourceName: "monkey-1")),
    CustomImage(title: "Monkey 1", image: #imageLiteral(resourceName: "monkey-2")),
    CustomImage(title: "Monkey 1", image: #imageLiteral(resourceName: "monkey-3"))
]

let beachImages = [
    CustomImage(title: "Beach 1", image: #imageLiteral(resourceName: "beach-1")),
    CustomImage(title: "Beach 2", image: #imageLiteral(resourceName: "beach-2")),
    CustomImage(title: "Beach 3", image: #imageLiteral(resourceName: "beach-3")),
    CustomImage(title: "Beach 4", image: #imageLiteral(resourceName: "beach-4"))
]

override func viewDidLoad() {
    super.viewDidLoad()
    title = "Images"

    setupCollectionViews()
}

fileprivate func setupCollectionViews() {
    // Heights
    perspectiveCV.heightAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.8).isActive = true
    monkeyCV.heightAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.8).isActive = true
    beachCV.heightAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.8).isActive = true

    // Left and right padding
    perspectiveCV.contentInset = UIEdgeInsets(top: 0, left: 20, bottom: 0, right: 20)
    monkeyCV.contentInset = UIEdgeInsets(top: 0, left: 20, bottom: 0, right: 20)
    beachCV.contentInset = UIEdgeInsets(top: 0, left: 20, bottom: 0, right: 20)

    // Hide scrolling indicator
    perspectiveCV.showsHorizontalScrollIndicator = false
    monkeyCV.showsHorizontalScrollIndicator = false
    beachCV.showsHorizontalScrollIndicator = false
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    switch collectionView {
    case monkeyCV:
        return monkeyImages.count
    case beachCV:
        return beachImages.count
    default:
        return perspectiveImages.count
    }
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    switch collectionView {
    case monkeyCV:
        let monkeyCell = monkeyCV.dequeueReusableCell(withReuseIdentifier: "monkeyCell", for: indexPath) as! ImageCollectionViewCell
        monkeyCell.backgroundColor = UIColor.systemOrange
        monkeyCell.data = monkeyImages[indexPath.row]
        return monkeyCell
    case beachCV:
        let beachCell = beachCV.dequeueReusableCell(withReuseIdentifier: "beachCell", for: indexPath) as! ImageCollectionViewCell
        beachCell.backgroundColor = UIColor.systemBlue
        beachCell.data = beachImages[indexPath.row]
        return beachCell
    default:
        let perspectiveCell = perspectiveCV.dequeueReusableCell(withReuseIdentifier: "perspectiveCell", for: indexPath) as! ImageCollectionViewCell
        perspectiveCell.backgroundColor = UIColor.systemRed
        perspectiveCell.data = perspectiveImages[indexPath.row]
        return perspectiveCell
    }
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: collectionView.frame.width * 0.8, height: collectionView.frame.width * 0.8)
}

}

以下是我的自定义UICollectionViewCell：

import UIKit

class ImageCollectionViewCell: UICollectionViewCell {

var data: CustomImage? {
    didSet {
        guard let data = data else { return }
        bg.image = data.image
    }
}

fileprivate let bg: UIImageView = {
    let iv = UIImageView()
    iv.translatesAutoresizingMaskIntoConstraints = false
    iv.contentMode = .scaleAspectFit
    iv.clipsToBounds = true
    return iv
}()

override init(frame: CGRect) {
    super.init(frame: frame)

    bg.topAnchor.constraint(equalTo: contentView.topAnchor).isActive = true
    bg.leadingAnchor.constraint(equalTo: contentView.leadingAnchor).isActive = true
    bg.trailingAnchor.constraint(equalTo: contentView.trailingAnchor).isActive = true
    bg.bottomAnchor.constraint(equalTo: contentView.bottomAnchor).isActive = true

    contentView.addSubview(bg)
}

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

这是我的故事板

你能给我解释一下我的密码出了什么问题吗？

我的设置：

• 迅捷版: 5.1.3
• Xcode版本: 11.3.1
• 目标iOS版本: 13.2
• MacBook Pro (13英寸，2016年，4个雷电3端口) MacOS Catalina 10.15.2 (19C 57)

Answer 1

看起来您还没有建立分配给每个集合视图的委托/数据源。

在您的视图中，确实加载了将委托和数据源连接到每个集合视图。

self.mycollectionView1.delegate = self
self.mycollectionView1.datasource = self
self.mycollectionView2.delegate = self
self.mycollectionView2.datasource = self
self.mycollectionView3.delegate = self
self.mycollectionView3.datasource = self

您还可以通过故事板设置委托和数据源。您可以选择每个collectionView和ctrl +拖动到您的ViewController，而不是视图！

​

注意上面图像中突出显示的部分。这表明你的viewController。Ctrl +将每个集合视图拖到该位置，然后单击委托和数据源。

编辑

而不是像在这里那样使用开关语句

switch collectionView {
    case monkeyCV:
        let monkeyCell = monkeyCV.dequeueReusableCell(withReuseIdentifier: "monkeyCell", for: indexPath) as! ImageCollectionViewCell
        monkeyCell.backgroundColor = UIColor.systemOrange
        monkeyCell.data = monkeyImages[indexPath.row]
        return monkeyCell
    case beachCV:
        let beachCell = beachCV.dequeueReusableCell(withReuseIdentifier: "beachCell", for: indexPath) as! ImageCollectionViewCell
        beachCell.backgroundColor = UIColor.systemBlue
        beachCell.data = beachImages[indexPath.row]
        return beachCell
    default:
        let perspectiveCell = perspectiveCV.dequeueReusableCell(withReuseIdentifier: "perspectiveCell", for: indexPath) as! ImageCollectionViewCell
        perspectiveCell.backgroundColor = UIColor.systemRed
        perspectiveCell.data = perspectiveImages[indexPath.row]
        return perspectiveCell
    }

尝试像这样建立你的细胞

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath)-> UICollectionViewCell {
      let cell = myCollectionView1.dequeueResuableCell(withReuseIdentifier: "myIdentifier", for: indexPath) as! mycustomCellClass
      cell.backgroundColor = UIColor.systemOrange
      return cell


      if collectionView == mycollectionView2 {
          let cell2 = mycollectionView2.dequeueResuableCell(withReuseIdentifier: "myIdentifier2", for: indexPath) as! mycustomCellClass
          cell2.backgroundColor = UIColor.systemBlue
      }

}

诸若此类。您还可能需要修改您的numberOfItemsInSection函数来替换那个开关语句。

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    switch collectionView {
    case monkeyCV:
        return monkeyImages.count
    case beachCV:
        return beachImages.count
    default:
        return perspectiveImages.count
    }
}

从上面改为下面

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
     if (collectionView == mycollectionView1 { 
        return monkeyImages.count
     } else if (collectionView == myCollectionView2 {
        return beachImages.count
     } else {
       //this is your final collectionview 
       return persepctiveImages.count
     }
}

编辑2？

尝试删除sizeForItemAt

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: collectionView.frame.width * 0.8, height: collectionView.frame.width * 0.8)
}

转到你的故事板，物理地拖动你想要的单元格的大小。在“大小”检查器内的右侧面板上，确保“估计大小”选项设置为“无”。

你也可以试试这个。

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: (collectionView.frame.size.width/3), height: collectionView.frame.size.height)
}

3的分裂产生三个细胞。