Swift中如何正确排序含数字的字符串数组及关联数组？

问题背景 #

需要对格式为"Day X"的主数组排序，同时同步排序另外三个关联数组。当前代码采用字符串字典序排序，得到错误结果：

排序后主数组示例：["Day 9","Day 8","Day 7","Day 6","Day 5","Day 4","Day 3","Day 2","Day 13","Day 12","Day 11","Day 1"]

错误根源是字符串字典序比较逻辑："Day 13"会排在"Day 2"前面（因为字符"1"的ASCII值小于"2"），而非按数字大小排序。

解决方案 #

核心是提取主数组元素中的数字值，基于数值大小排序，同时保留关联数组的对应关系。以下两种实现方式均可：

方式1：打包元组后排序 #

将四个数组的对应元素打包成元组，排序时提取主元素的数字进行比较，再拆分回原数组结构：

var mainDayArray = ["Day 1","Day 2","Day 3","Day 4","Day 5","Day 6","Day 7","Day 8","Day 9","Day 10","Day 11","Day 12","Day 13"]
var timeArray = ["06:09 PM", "06:09 PM", "06:08 PM", "06:08 PM", "06:08 PM", "06:07 PM", "06:07 PM", "06:07 PM", "06:07 PM", "06:06 PM", "06:06 PM", "06:06 PM", "06:06 PM"]
var dateArray = ["Oct 1", "Oct 2", "Oct 3", "Oct 4", "Oct 5", "Oct 7", "Oct 4", "Oct 5", "Oct 9", "Nov 2", "Nov 3", "Nov 4", "Nov 01"]
var studentNameArray =["as","ab","vf","sd","fd","gr","ht","jh","kl","mn","sf","ts","at"]

// 打包所有关联数据为元组数组
let combinedArray = zip(zip(zip(mainDayArray, timeArray), dateArray), studentNameArray).map {
    ($0.0.0, $0.0.1, $0.1, $1)
}

// 按主数组元素的数字降序排序（升序则替换为 <）
let sortedCombined = combinedArray.sorted {
    guard let num1 = Int($0.0.components(separatedBy: " ").last ?? ""),
          let num2 = Int($1.0.components(separatedBy: " ").last ?? "") else {
        return false
    }
    return num1 > num2
}

// 拆分回各个数组
let sortedCompletedDayArray = sortedCombined.map { $0.0 }
let sortedCompletedTimeArray = sortedCombined.map { $0.1 }
let sortedCompletedDateArray = sortedCombined.map { $0.2 }
let sortedCompletedStudentNamesArray = sortedCombined.map { $0.3 }

方式2：优化原索引排序逻辑 #

保留原代码的索引排序思路，修改排序逻辑为基于数字比较：

var mainDayArray = ["Day 1","Day 2","Day 3","Day 4","Day 5","Day 6","Day 7","Day 8","Day 9","Day 10","Day 11","Day 12","Day 13"]
var timeArray = ["06:09 PM", "06:09 PM", "06:08 PM", "06:08 PM", "06:08 PM", "06:07 PM", "06:07 PM", "06:07 PM", "06:07 PM", "06:06 PM", "06:06 PM", "06:06 PM", "06:06 PM"]
var dateArray = ["Oct 1", "Oct 2", "Oct 3", "Oct 4", "Oct 5", "Oct 7", "Oct 4", "Oct 5", "Oct 9", "Nov 2", "Nov 3", "Nov 4", "Nov 01"]
var studentNameArray =["as","ab","vf","sd","fd","gr","ht","jh","kl","mn","sf","ts","at"]

// 获取排序后的索引（按数字降序，升序替换为 <）
let offsets = mainDayArray.enumerated().sorted {
    guard let num1 = Int($0.element.components(separatedBy: " ").last ?? ""),
          let num2 = Int($1.element.components(separatedBy: " ").last ?? "") else {
        return false
    }
    return num1 > num2
}.map { $0.offset }

// 生成排序后的数组
let sortedCompletedDayArray = offsets.map { mainDayArray[$0] }
let sortedCompletedDateArray = offsets.map { dateArray[$0] }
let sortedCompletedTimeArray = offsets.map { timeArray[$0] }
let sortedCompletedStudentNamesArray = offsets.map { studentNameArray[$0] }

关键说明 #

• 通过components(separatedBy: " ").last提取"Day X"中的数字部分，转换为Int后进行数值比较，彻底避免字典序排序的错误。
• 如需升序排序，仅需将排序闭包中的>替换为<即可。

内容的提问来源于stack exchange，提问作者Abhishek kumar