如何快速按日期对对象数组进行分组？

Question

需要按日期分组。响应采用排序格式。需要在日期上应用过滤器来分组。 来自后端的响应：

[
    {
    "date": "date1"
    }, 
    {
    "date": "date1"
    },
    {
    "date": "date1"
    },
    {
    "date": "date2"
    },
    {
    "date": "date2"
    },
    {
    "date": "date3"
    }
]

必填：

[
    [
        "date": "2017-05-30T12:40:39.000Z",
        "message": [
            {
                "date_time": 2017-05-30T12: 40: 39.000Z
            }
        ]
    ],
    [
        "date": "2017-05-31T05:43:17.000Z",
        "message": [
            {
                "date_time": 2017-05-31T05: 43: 17.000Z
            },
            {
                "date_time": 2017-05-31T05: 44: 15.000Z
            },
            {
                "date_time": 2017-05-31T05: 44: 38.000Z
            }
        ]
    ]
]

我已经检查了多个答案，但无法找到一个好的解决方案。

Answer 1

修改 ElegyD 处理可选日期对象的解决方案

    fileprivate func compare(date:Date, to:Date, toGranularity:Calendar.Component)->ComparisonResult{
    return Calendar.current.compare(date, to: to, toGranularity: toGranularity)
}

    func groupSort(ascending: Bool = true, toGranularity:Calendar.Component, byDate dateKey: (Iterator.Element) -> Date?) -> [[Iterator.Element]] {
    var categories: [[Iterator.Element]] = []
    for element in self {
        guard let key = dateKey(element) else {
            continue
        }
        guard let dayIndex = categories.firstIndex(where: { $0.contains(where: {
            if let date = dateKey($0){
                return Calendar.current.isDate(date, inSameDayAs: key)
            }
            return false
        })
        }) else {
            guard let nextIndex = categories.firstIndex(where: {
                $0.contains(where: {
                    if let date = dateKey($0){
                        return self.compare(date: date, to: key, toGranularity: toGranularity) == (ascending ? .orderedDescending : .orderedAscending)
                    }
                    return false
                })
            }) else {
                categories.append([element])
                continue
            }
            categories.insert([element], at: nextIndex)
            continue
        }
        
        guard let nextIndex = categories[dayIndex].firstIndex(where: {
            if let date = dateKey($0){
                return self.compare(date: date, to: key, toGranularity: toGranularity) == (ascending ? .orderedDescending : .orderedAscending)
            }
            return false
        }) else {
            categories[dayIndex].append(element)
            continue
        }
        categories[dayIndex].insert(element, at: nextIndex)
    }
    return categories
}

用法 结构数据项{ 变量日期：日期？ }

让 items = [DataItem(), DataItem(date:Date())] let grouped = items.groupSort(toGranularity: .month, byDate: {$0.date })

Answer 2

您可以使用数组扩展。

extension Array {
  func sliced(by dateComponents: Set<Calendar.Component>, for key: KeyPath<Element, Date>) -> [Date: [Element]] {
    let initial: [Date: [Element]] = [:]
    let groupedByDateComponents = reduce(into: initial) { acc, cur in
      let components = Calendar.current.dateComponents(dateComponents, from: cur[keyPath: key])
      let date = Calendar.current.date(from: components)!
      let existing = acc[date] ?? []
      acc[date] = existing + [cur]
    }

    return groupedByDateComponents
  }
}

您可以使用 Swift 5 KeyPath 在任何模型属性上使用它

let grouped = models.sliced(by: [.year, .month, .day], for: \.createdAt)

Answer 3

这是我按日期分组的解决方案（只是日、月和年）：

let groupDic = Dictionary(grouping: arr) { (pendingCamera) -> DateComponents in

    let date = Calendar.current.dateComponents([.day, .year, .month], from: (pendingCamera.date)!)

    return date
}

Answer 4

谢谢ElegyD。这对我有用。

extension Sequence {
    func groupSort(ascending: Bool = true, byDate dateKey: (Iterator.Element) -> Date) -> [[Iterator.Element]] {
        var categories: [[Iterator.Element]] = []
        for element in self {
            let key = dateKey(element)
            guard let dayIndex = categories.index(where: { $0.contains(where: { Calendar.current.isDate(dateKey($0), inSameDayAs: key) }) }) else {
                guard let nextIndex = categories.index(where: { $0.contains(where: { dateKey($0).compare(key) == (ascending ? .orderedDescending : .orderedAscending) }) }) else {
                    categories.append([element])
                    continue
                }
                categories.insert([element], at: nextIndex)
                continue
            }

            guard let nextIndex = categories[dayIndex].index(where: { dateKey($0).compare(key) == (ascending ? .orderedDescending : .orderedAscending) }) else {
                categories[dayIndex].append(element)
                continue
            }
            categories[dayIndex].insert(element, at: nextIndex)
        }
        return categories
    }
}

用法：

class Model {
    let date: Date!
    let anotherProperty: String!

    init(date: Date, _ anotherProperty: String) {
        self.date = date
        self.anotherProperty = anotherProperty
    }
}

let modelArray = [
    Model(date: Date(), anotherProperty: "Original Date"),
    Model(date: Date().addingTimeInterval(86400), anotherProperty: "+1 day"),
    Model(date: Date().addingTimeInterval(172800), anotherProperty: "+2 days"),
    Model(date: Date().addingTimeInterval(86401), anotherProperty: "+1 day & +1 second"),
    Model(date: Date().addingTimeInterval(172801), anotherProperty: "+2 days & +1 second"),
    Model(date: Date().addingTimeInterval(86400), anotherProperty: "+1 day"),
    Model(date: Date().addingTimeInterval(172800), anotherProperty: "+2 days")
]

let groupSorted = modelArray.groupSort(byDate: { $0.date })
print(groupSorted) // [["Original Date"], ["+1 day", "+1 day", "+1 day & +1 second"], ["+2 days", "+2 days", "+2 days & +1 second"]]

let groupSortedDesc = modelArray.groupSort(ascending: false, byDate: { $0.date })
print(groupSortedDesc) // [["+2 days & +1 second", "+2 days", "+2 days"], ["+1 day & +1 second", "+1 day", "+1 day"], ["Original Date"]]

Answer 5

您可以像这样使用flatMap 和filter 将您的数组分组到字典中。

let datesArray = yourArray.flatMap { $0["date"] as? String } // return array of date
var dic = [String:[[String:Any]]]() // Your required result
datesArray.forEach {
    let dateKey = $0
    let filterArray = yourArray.filter { $0["date"] as? String == dateKey }
    dic[$0] = filterArray
}
print(dic)

注意：确保字典没有任何顺序，这样date 的打印顺序可能会改变。