以编程方式向集合视图添加约束Swift

import UIKit

class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
    
    var collectionView: UICollectionView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建集合视图布局
        let layout = UICollectionViewFlowLayout()
        layout.itemSize = CGSize(width: 100, height: 100)
        
        // 创建集合视图
        collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: layout)
        collectionView.delegate = self
        collectionView.dataSource = self
        collectionView.backgroundColor = .white
        
        // 添加集合视图到视图层次结构中
        view.addSubview(collectionView)
        
        // 添加约束
        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)
        ])
        
        // 注册集合视图的单元格
        collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "Cell")
    }
    
    // 实现集合视图的代理方法和数据源方法...
}