UIKit中如何實現一個自定義的日歷視圖組件

要實現一個自定義的日歷視圖組件，可以使用UICollectionView來顯示日期，并根據實際需求自定義日期的樣式和功能。

以下是一個簡單的示例代碼：

import UIKit

class CustomCalendarView: UIView, UICollectionViewDataSource, UICollectionViewDelegate {
    
    private var collectionView: UICollectionView!
    private var dates: [Date] = []
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        setupCollectionView()
        setupDates()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    private func setupCollectionView() {
        let layout = UICollectionViewFlowLayout()
        layout.itemSize = CGSize(width: frame.width/7, height: frame.width/7)
        
        collectionView = UICollectionView(frame: frame, collectionViewLayout: layout)
        collectionView.dataSource = self
        collectionView.delegate = self
        collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "Cell")
        
        addSubview(collectionView)
    }
    
    private func setupDates() {
        // 獲取當前月份的所有日期
        let currentDate = Date()
        let calendar = Calendar.current
        let range = calendar.range(of: .day, in: .month, for: currentDate)!
        
        dates = range.compactMap { calendar.date(byAdding: .day, value: $0-1, to: calendar.startOfDay(for: currentDate)) }
        
        collectionView.reloadData()
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return dates.count
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
        let date = dates[indexPath.item]
        
        let formatter = DateFormatter()
        formatter.dateFormat = "d"
        
        let label = UILabel(frame: cell.contentView.bounds)
        label.textAlignment = .center
        label.text = formatter.string(from: date)
        cell.contentView.addSubview(label)
        
        // 自定義日期樣式
        if calendar.isDateInToday(date) {
            cell.backgroundColor = .red
            label.textColor = .white
        } else {
            cell.backgroundColor = .clear
            label.textColor = .black
        }
        
        return cell
    }
}

在使用時，只需要將CustomCalendarView添加到視圖中即可：

let calendarView = CustomCalendarView(frame: CGRect(x: 0, y: 0, width: 300, height: 300))
view.addSubview(calendarView)

這樣就可以實現一個簡單的自定義日歷視圖組件，可以根據需求進一步擴展和優化。