如何在CoreData中按列值对记录进行分组？

// 创建一个NSFetchRequest对象
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "YourEntity")

// 创建一个NSExpressionDescription对象来定义分组的列
let expressionDescription = NSExpressionDescription()
expressionDescription.name = "groupedValue"
expressionDescription.expression = NSExpression(forKeyPath: "columnName") // 将"columnName"替换为实际的列名
expressionDescription.expressionResultType = .stringAttributeType

// 设置fetchRequest的propertiesToFetch属性为分组的列
fetchRequest.propertiesToFetch = [expressionDescription]

// 设置fetchRequest的propertiesToGroupBy属性为分组的列
fetchRequest.propertiesToGroupBy = [expressionDescription]

// 执行fetchRequest并获取结果
do {
    let result = try context.fetch(fetchRequest)
    if let groupedResults = result as? [[String: Any]] {
        for group in groupedResults {
            if let groupedValue = group["groupedValue"] as? String {
                // 处理每个分组的记录
                print("Grouped value: \(groupedValue)")
            }
        }
    }
} catch {
    print("Error fetching data: \(error)")
}