使用 NSDate/NSCalendar 测试周年日期

Question

我试图弄清楚如何确定今天是否是 NSCalendar 项目的周年纪念日。我发现的所有内容都会将特定日期的月、日、年与另一个特定的月、日和年进行比较。粒度对我不利，因为它首先比较的是年份。

这是我到目前为止所得到的。我已经阅读了文档，但我遗漏了一些东西（基本）。这是什么？

// get the current date
let calendar = NSCalendar.currentCalendar()
var dateComponents = calendar.components([.Month, .Day], fromDate: NSDate())

let today = calendar.dateFromComponents(dateComponents)

var birthDates = [NSDate]()

let tomsBirthday = calendar.dateWithEra(1, year: 1964, month: 9, day: 3, hour: 0, minute: 0, second: 0, nanosecond: 0)
birthDates.append(tomsBirthday!)

let dicksBirthday = calendar.dateWithEra(1, year: 1952, month: 4, day: 5, hour: 0, minute: 0, second: 0, nanosecond: 0)
birthDates.append(dicksBirthday!)

let harrysBirthday = calendar.dateWithEra(1, year: 2015, month: 10, day: 27, hour: 0, minute: 0, second: 0, nanosecond: 0)
birthDates.append(harrysBirthday!)

for birthday in birthDates {
    // compare the month and day to today's month and day
    // if birthday month == today's month {
    //      if birthday day == today's day {
    //             do something
    //      }

}

Answer 1

为了进行日期比较，在将 2 月 29 日视为非闰年的 3 月 1 日时，您需要使用此人生日的月份和日期部分来构造当前年份的 NSDate。

另外，在构造NSDate 来比较日期时，不要使用午夜作为时间。 Some days don't have a midnight in some time zones. 改用中午。

struct Person {
    let name: String
    let birthYear: Int
    let birthMonth: Int
    let birthDay: Int
}

let people = [
    Person(name: "Tom", birthYear: 1964, birthMonth: 9, birthDay: 3),
    Person(name: "Dick", birthYear: 1952, birthMonth: 4, birthDay: 5),
    Person(name: "Harry", birthYear: 2015, birthMonth: 10, birthDay: 28)
]

let calendar = NSCalendar.autoupdatingCurrentCalendar()

let todayComponents = calendar.components([.Era, .Year, .Month, .Day], fromDate: NSDate())
todayComponents.hour = 12
let todayNoon = calendar.dateFromComponents(todayComponents)

for person in people {
    let components = todayComponents.copy() as! NSDateComponents
    // DON'T copy person.birthYear
    components.month = person.birthMonth
    components.day = person.birthDay
    let birthdayNoon = calendar.dateFromComponents(components)
    if todayNoon == birthdayNoon {
        print("Happy birthday, \(person.name)!")
    }
}