如何在swift中将字符放在单独的collectionViewCell中

import UIKit

class CharacterCell: UICollectionViewCell {
    // 添加一个UILabel用于显示字符
    let characterLabel: UILabel = {
        let label = UILabel()
        label.textAlignment = .center
        label.font = UIFont.systemFont(ofSize: 16)
        return label
    }()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        // 设置字符Label的布局
        characterLabel.frame = contentView.bounds
        contentView.addSubview(characterLabel)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

import UIKit

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
    // 创建一个UICollectionView
    let collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .vertical
        let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
        collectionView.backgroundColor = .white
        return collectionView
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 设置collectionView的dataSource和delegate
        collectionView.dataSource = self
        collectionView.delegate = self
        
        // 注册CharacterCell
        collectionView.register(CharacterCell.self, forCellWithReuseIdentifier: "CharacterCell")
        
        // 添加collectionView到视图中
        view.addSubview(collectionView)
        
        // 设置collectionView的布局
        collectionView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            collectionView.topAnchor.constraint(equalTo: view.topAnchor),
            collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            collectionView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            collectionView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])
    }
    
    // MARK: - UICollectionViewDataSource
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        // 返回字符的数量
        return characters.count
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CharacterCell", for: indexPath) as! CharacterCell
        
        // 设置字符Label的文本
        cell.characterLabel.text = characters[indexPath.item]
        
        return cell
    }
    
    // MARK: - UICollectionViewDelegateFlowLayout
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        // 设置每个cell的大小
        return CGSize(width: 50, height: 50)
    }
}

// 示例字符数组
let characters = ["A", "B", "C", "D", "E", "F", "G"]