Question

我在词典方面遇到麻烦。

例如，

我当前的数据

["date": "2018-01-01", "name": "New Year"], ["date": "2018-01-31", "name": "Public holiday"],["date": "2018-02-14", "name": "Valentine's Day"], ["date": "2018-02-28", "name": "Public Holiday"]

如何转换为

["month": ["January": ["date": "2018-01-01", "name": "New Year"], ["date": "2018-01-31", "name": "Public holiday"]],["February": ["date": "2018-02-14", "name": "Valentine's Day"], ["date": "2018-02-28", "name": "Public Holiday"]]]

Answer 1

您可以使用DateFormatter将String格式的日期（yyyy-MM-dd）读取到Date实例中，然后重新使用格式化程序来提取完整的月份名称（ MMMM）中的日期作为您的String键。

将其与reduce(into:)合并以处理data数组：

let data = [
    ["date": "2018-01-01", "name": "New Year"],
    ["date": "2018-01-31", "name": "Public holiday"],
    ["date": "2018-02-14", "name": "Valentine's Day"],
    ["date": "2018-02-28", "name": "Public Holiday"]
]

let monthCategorizedData = data
    .reduce(into: (result: [String: [[String: String]]](),
                   formatter: DateFormatter(),
                   calendar: Calendar(identifier: .gregorian))) {(args, data) in
    var month = "Unknown"
    args.formatter.dateFormat = "yyyy-MM-dd" // format: read date from string
    if let date = data["date"].flatMap({ args.formatter.date(from: $0)}) {
        args.formatter.dateFormat = "MMMM"   // format: read month (as string) from date
        month = args.formatter.string(from: date)
    }
    args.result[month] = args.result[month, default: []] + [data]
}.result

print(monthCategorizedData)
/* ["January":  [["date": "2018-01-01", "name": "New Year"],
                 ["date": "2018-01-31", "name": "Public holiday"]],
    "February": [["date": "2018-02-14", "name": "Valentine\'s Day"],
                 ["date": "2018-02-28", "name": "Public Holiday"]]] */

如果数据的日期无效（String格式的Date失败，或者"date"中不存在data键），以上内容会将它们分类为键Unknown。如果您只想丢弃此类数据（这样的失败应该是意外的），则可以将以上内容修改为：

let monthCategorizedData = data
    .reduce(into: (result: [String: [[String: String]]](),
                   formatter: DateFormatter(),
                   calendar: Calendar(identifier: .gregorian))) {(args, data) in
    args.formatter.dateFormat = "yyyy-MM-dd" // format: read date from string
    if let date = data["date"].flatMap({ args.formatter.date(from: $0)}) {
        args.formatter.dateFormat = "MMMM"   // format: read month (as string) from date
        let month = args.formatter.string(from: date)
        args.result[month] = args.result[month, default: []] + [data]
    }
}.result

将结果进一步嵌套一层到"month"中的[String: [String : [[String : String]]]]键的值中是很直接的：

let categorizedData = ["month": monthCategorizedData]

print(categorizedData)
/* ["month": ["January":  [["date": "2018-01-01", "name": "New Year"],
                           ["date": "2018-01-31", "name": "Public holiday"]],
              "February": [["date": "2018-02-14", "name": "Valentine\'s Day"],
                           ["date": "2018-02-28", "name": "Public Holiday"]]]] */

Answer 2

虽然我不是专家，但对我来说问题似乎就在于你如何获得 “ date” =“ year-month-day”月的值如果你能够削减多少呢？或仅获得第5和第6个字符，它将成为您需要的月份数基于您可以使用if或switch并制作一个字典数组甚至只是字典，然后您可以根据需要将其添加到数组中。

因此在获得本月编号后，将是这样：

var dict：[String：[[String：String]]] = [：]

dict [“ janury”] = [[“ 2012-01-12”：“事件”]，[“ 2012-01-13”：“ event2”]]

如果monthNumber == 1 {

dict["janury"]?.append(["2012-01-14":"event3"])

}

然后每个月，如果总共12个最终切换为12条语句，则需要新的

关于如何获得这个字符串的值，我还不知道，但是我几乎可以肯定，谷歌可以帮助它或者比我的经验更好的人

Answer 3

Dictionary有一种方法Screenshot，可以通过一种非常聪明的方式做到这一点。

然后将date参数转换为Date，然后转换为带有DateFormatter的月份名称

let array = [["date": "2018-01-01", "name": "New Year"],
             ["date": "2018-01-31", "name": "Public holiday"],
             ["date": "2018-02-14", "name": "Valentine's Day"],
             ["date": "2018-02-28", "name": "Public Holiday"]]

let dictionary = Dictionary(grouping: array) { (item) -> String in
    let formatter = DateFormatter()
    formatter.dateFormat = "yyyy-MM-dd"
    guard let dateString = item["date"],
        let date = formatter.date(from: dateString) else  { return "Unknown" }
    formatter.dateFormat = "MMMM"
    return formatter.string(from: date)
}

print(["months" : dictionary])

如何将日期合并成字典？

3 个答案: