Question

我正在尝试使用string：int类型的字典数组。我试图用一年的日期（作为字符串）和0（对于所有的整数）初始化该数组。

但是，我面临各种错误。编译器认为我的print语句不明确。

我的代码：

class Dates {
    static func printDatesBetweenInterval(_ startDate: Date, _ endDate: Date) -> [Dictionary<String, Int>] {
        var details = [Dictionary<String, Int>]()
        var startDate = startDate
        let calendar = Calendar.current

        let fmt = DateFormatter()
        fmt.dateFormat = "yyyy-MM-dd"

        while startDate <= endDate {
            let sDate =  fmt.string(from: startDate)
            print (sDate)
            details.append([sDate : 0])
            startDate = calendar.date(byAdding: .day, value: 1, to: startDate)!
        }

        return details
    }

    static func dateFromString(_ dateString: String) -> Date {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd"
        return dateFormatter.date(from: dateString)!
    }
}

struct Attendee {
    var masterStudentdetails = [Dictionary<String, Int>]()

    init() {
        masterStudentdetails = Dates.printDatesBetweenInterval(Dates.dateFromString("2018-08-22"), Dates.dateFromString("2019-08-20"))
        for (dayStr, trackNum) in masterStudentdetails {
            print(dayStr) //This line is causes error.
        }
    }

Answer 1

masterStudentDetails是一个字典数组。因此，for in的结果为[String: Int]，而不是键值对。

您需要迭代数组，然后迭代每个字典中的键值对。

init() {
    masterStudentdetails = Dates.printDatesBetweenInterval(Dates.dateFromString("2018-08-22"), Dates.dateFromString("2019-08-20"))
    for dictionary in masterStudentdetails {
        for (dayStr, trackNum) in dictionary.enumerated() {
            print(dayStr)
        }
    }
}

但由于每个字典中只有一个键值对，您可以这样做：

init() {
    masterStudentdetails = Dates.printDatesBetweenInterval(Dates.dateFromString("2018-08-22"), Dates.dateFromString("2019-08-20"))
    for dictionary in masterStudentdetails {
        if let pair = dictionary.first {
            print(pair.key)
        }
    }
}

日期的字典数组

1 个答案: