过滤一组 NSDate for Today, Yesterday 用于绘图

Question

我有一组带有时间戳的日记条目。

class JournalNoteEntry {
var timeCreated: NSDate?
var value: Int?
var note: String?
}

我如何过滤此数组以获取今天、昨天、本周、本月等的条目并绘制我的 value 与 timeCreated 并标记 X 轴

我已经为这个基本需求搜索了很多，但找不到答案。

有人可以帮忙吗...

Answer 1

let predicate = NSPredicate(format: "timeCreated == %f", NSDate().timeIntervalSince1970)
let arrFiltedArray =   array .filteredArrayUsingPredicate(predicate)

其中 timeCreated 包含您日期的 timeIntervalSince1970，意味着将您的数据类型从 NSDate 转换为 double

Answer 2

由于您是在 Swift 3 中编写的，因此您应该使用本机 Swift 的类型而不是基金会的 classes（以 NS... 开头的那些):

class JournalNoteEntry {
    var timeCreated: Date?
    var value: Int?
    var note: String?
}

关于您的问题：让我们编写一个简单的函数来过滤开始日期和结束日期之间的所有条目：

func entries(in journal: [JournalNoteEntry],  from: Date, to: Date) -> [JournalNoteEntry] {
    return journal.filter {
        guard let timeCreated = [=11=].timeCreated else {
            return false
        }

        // Notice that this is half-open range
        return from <= timeCreated && timeCreated < to
    }
}

您的大部分工作将用于确定日期范围。一种方法是通过扩展 Calendar class:

extension Calendar {
    func todayRange() -> (Date, Date) {
        let startDate = self.startOfDay(for: Date())
        let endDate   = self.date(byAdding: .day, value: 1, to: startDate)!
        return (startDate, endDate)
    }

    func yesterdayRange() -> (Date, Date) {
        let endDate   = self.startOfDay(for: Date())
        let startDate = self.date(byAdding: .day, value: -1, to: endDate)!
        return (startDate, endDate)
    }

    func thisWeekRange() -> (Date, Date) {
        var components = DateComponents()
        components.weekday = self.firstWeekday

        let startDate = self.nextDate(after: Date(), matching: components, matchingPolicy: .nextTime, direction: .backward)!
        let endDate   = self.nextDate(after: startDate, matching: components, matchingPolicy: .nextTime)!
        return (startDate, endDate)
    }

    func thisMonthRange() -> (Date, Date) {
        var components = self.dateComponents([.era, .year, .month], from: Date())
        components.day = 1

        let startDate = self.date(from: components)!
        let endDate   = self.date(byAdding: .month, value: 1, to: startDate)!

        return (startDate, endDate)
    }
}

// Run this in Playground to see it formatted in your local timezone
// If you call print(), it will always display in UTC
// Assuming today = Nov 7, 2016
Calendar.current.todayRange()       // "Nov 7, 2016, 12:00 AM", "Nov 8, 2016, 12:00 AM"
Calendar.current.yesterdayRange()   // "Nov 6, 2016, 12:00 AM", "Nov 7, 2016, 12:00 AM"
Calendar.current.thisWeekRange()    // "Nov 6, 2016, 12:00 AM", "Nov 13, 2016, 12:00 AM"
Calendar.current.thisMonthRange()   // "Nov 1, 2016, 12:00 AM", "Dec 1, 2016, 12:00 AM"

获取当月所有日记账分录：

// journal is an array of JournalNoteEntry
let (startDate, endDate) = Calendar.current.thisMonthRange()
let results = entries(in: journal, from: startDate, to: endDate)

过滤一组 NSDate for Today, Yesterday 用于绘图

Filter an array of NSDate for Today, Yesterday for plotting

arrays

plot

nsdate

ios

swift