ios - Swift - 获取从今天开始的最后 7 天数组

Question

如何获取该月的前 7 天 我知道如果今天是 18 日如何获取，但如果今天是 11 月 3 日怎么办？如何在 Int 中获取上个月(10 月)的最后 4 天？

Answer 1

使用 NSCalendar 和 NSDateComponents:

let cal = NSCalendar.currentCalendar()
// start with today
var date = cal.startOfDayForDate(NSDate())

var days = [Int]()

for i in 1 ... 7 {
    // get day component:
    let day = cal.component(.DayCalendarUnit, fromDate: date)
    days.append(day)

    // move back in time by one day:
    date = cal.dateByAddingUnit(.DayCalendarUnit, value: -1, toDate: date, options: nil)!
}

println(days)

Swift 2.2 (Xcode 7.3.1) 更新:

let cal = NSCalendar.currentCalendar()
var date = cal.startOfDayForDate(NSDate())
var days = [Int]()
for i in 1 ... 7 {
    let day = cal.component(.Day, fromDate: date)
    days.append(day)
    date = cal.dateByAddingUnit(.Day, value: -1, toDate: date, options: [])!
}
print(days)

Swift 3(Xcode 8 beta 2)更新:

let cal = Calendar.current
var date = cal.startOfDay(for: Date())
var days = [Int]()
for i in 1 ... 7 {
    let day = cal.component(.day, from: date)
    days.append(day)
    date = cal.date(byAdding: .day, value: -1, to: date)!
}
print(days)