TableView复杂排序：如何对分组内Cell按时间升序排列？

现有用于TableView分组展示的数组与数据结构如下：

var sections: [SectionContent] = []
var cells: [CellContent] = []

struct SectionContent {
    let sectionDate: Date
    let sectionContent: [CellContent]
}

struct CellContent {
    let cellDate: Date?
    var formattedDate: String {
        guard let text = cellDate else { return "" }
        return DateFormatter.stringDate.string(from: text)
    }
}

extension DateFormatter {
    static let stringDate: DateFormatter = {
        let formatterDate = DateFormatter()
        formatterDate.dateFormat = "MMM d, h:mm a"
        return formatterDate
    }()
}

目前已通过sections.sort { $0.sectionDate < $1.sectionDate }实现分组按日期升序排序，但需要实现单个分组内的Cell按对应时间升序排列（早时间在上，晚时间在下），现有构造分组的代码如下：

func sortByDate() {
    sections.removeAll()
    let dates = cells.reduce(into: Set<Date>()) { result, cells in
        let date = Calendar.current.startOfDay(for: cells.cellDate!)
        result.insert(date) }
    for date in dates {
        let dateComp = Calendar.current.dateComponents([.year, .month, .day], from: date)
        var sortedContent: [CellContent] = []
        cells.forEach { cells in
            let contComp = Calendar.current.dateComponents([.year, .month, .day], from: cells.cellDate!)
            if contComp == dateComp {
                sortedContent.append(cells) } }
        let newSection = SectionContent(sectionDate: date, sectionContent: sortedContent)
        sections.append(newSection) } }

只需在构造每个分组的sectionContent时，对筛选出的CellContent数组按cellDate升序排序即可，同时优化原代码中的强制解包问题避免崩溃：

修改后的完整sortByDate方法： #

func sortByDate() {
    sections.removeAll()
    
    // 提取所有cell对应的"当天起始时间"作为分组依据
    let dates = cells.reduce(into: Set<Date>()) { result, cell in
        guard let cellDate = cell.cellDate else { return }
        let dayStart = Calendar.current.startOfDay(for: cellDate)
        result.insert(dayStart)
    }
    
    for date in dates {
        let targetDayComp = Calendar.current.dateComponents([.year, .month, .day], from: date)
        
        // 筛选当前日期的cell并按时间升序排序
        let sortedCells = cells.filter { cell in
            guard let cellDate = cell.cellDate else { return false }
            let cellDayComp = Calendar.current.dateComponents([.year, .month, .day], from: cellDate)
            return cellDayComp == targetDayComp
        }.sorted { cellA, cellB in
            // 处理cellDate为nil的情况，将nil的cell放在分组末尾
            guard let dateA = cellA.cellDate, let dateB = cellB.cellDate else {
                return cellA.cellDate != nil && cellB.cellDate == nil
            }
            return dateA < dateB
        }
        
        let newSection = SectionContent(sectionDate: date, sectionContent: sortedCells)
        sections.append(newSection)
    }
    
    // 保持分组整体按日期升序排列
    sections.sort { $0.sectionDate < $1.sectionDate }
}

核心修改说明： #

1. 用filter替代原有的forEach+append逻辑，代码更简洁高效
2. 在筛选后链式调用.sorted，直接对分组内的cell按cellDate升序排序，实现早时间在上的效果
3. 替换所有强制解包!为guard let可选绑定，避免因cellDate为nil导致的运行时崩溃
4. 增加了cellDate为nil的排序规则，确保这类cell不会影响正常排序逻辑（可根据需求调整位置）

内容的提问来源于stack exchange，提问作者CalebGates