2

2010年7月15日だとしましょう。前週の最初の日、つまり7月5日を取得したいと思います。次の方法がありますが、うまくいきません。平日の属性に問題があるようです...

+ (NSDate *)getFirstDayOfPreviousWeek
{
// Get current date
NSCalendar *cal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *now = [NSDate date];

// Get today date at midnight
NSDateComponents *components = [cal components:( NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit | NSTimeZoneCalendarUnit) fromDate:now];
[components setHour:0];
[components setMinute:0];
[components setSecond:0];
NSInteger *dayNbr = [components weekday];
NSLog(@"week day:%@",dayNbr); // CRASH
NSDate *todayMidnight = [cal dateFromComponents:components];

// Get first day of previous week midnight
components = [[[NSDateComponents alloc] init] autorelease];
NSInteger *wd = [dayNbr intValue] * -1 + 1;
[components setWeekDay:wd];
[components setWeek:-1];
NSDate *newDate = [cal dateByAddingComponents:components toDate:todayMidnight options:0];
[cal release];

NSLog(@"new date:%@", newDate);

return newDate;
}

手伝ってもらえますか？

どうもありがとう、

リュック

4

2 に答える 2

8

ずっと簡単なはずだと思います

- (NSDate *)getFirstDayOfPreviousWeek
{
    NSCalendar *cal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDate *now = [NSDate date];
    NSLog(@"Current date: %@", now);

    // required components for today
    NSDateComponents *components = [cal components:( NSYearCalendarUnit | NSMonthCalendarUnit | NSWeekCalendarUnit | NSWeekdayCalendarUnit ) fromDate:now];

    // adjust them for first day of previous week (Monday)
    [components setWeekday:2];
    [components setWeek:([components week] - 1)];

    // construct new date and return
    NSDate *newDate = [cal dateFromComponents:components];
    NSLog(@"New date: %@", newDate);

    return newDate;
}

このソリューションは、週の最初の日が月曜日であることを前提としていることに注意してください。

于 2010-07-15T20:52:09.230 に答える
0

次のSwift3Playgroundコードは、任意の日付から前週の最初の日を取得する方法を示しています。

import Foundation

let calendar = Calendar(identifier: .gregorian)
let intialDate = Date()

// Prepare the new date components
var newDateComponents = calendar.dateComponents([.year, .month, .weekOfMonth], from: intialDate)
newDateComponents.weekOfMonth = newDateComponents.weekOfMonth! - 1 // get previous week
newDateComponents.weekday = 2 // sunday is 1, monday is 2

// Get the new date
let newDate = calendar.date(from: newDateComponents)
print(newDate ?? "Could not retrieve a date")

この操作を繰り返す必要がある場合は、コードを関数またはメソッドにリファクタリングできます。

import Foundation

func firstDayOfPreviousWeek(from date: Date) -> Date? {
    let calendar = Calendar(identifier: .gregorian)
    var newDateComponents = calendar.dateComponents([.year, .month, .weekOfMonth], from: date)
    newDateComponents.weekOfMonth = newDateComponents.weekOfMonth! - 1
    newDateComponents.weekday = 2
    return calendar.date(from: newDateComponents)
}

したがって、次のPlaygroundコードは、2010年7月15日から前週の最初の日を取得する方法を示しています。

import Foundation

func firstDayOfPreviousWeek(from date: Date) -> Date? {
    let calendar = Calendar(identifier: .gregorian)
    var newDateComponents = calendar.dateComponents([.year, .month, .weekOfMonth], from: date)
    newDateComponents.weekOfMonth = newDateComponents.weekOfMonth! - 1
    newDateComponents.weekday = 2
    newDateComponents.timeZone = TimeZone(abbreviation: "GMT")
    return calendar.date(from: newDateComponents)
}

let calendar = Calendar(identifier: .gregorian)
var july15Components = DateComponents()
july15Components.day = 15
july15Components.month = 7
july15Components.year = 2010
july15Components.timeZone = TimeZone(abbreviation: "GMT")
let july15 = calendar.date(from: july15Components)!
print(july15) // prints 2010-07-15 00:00:00 +0000

let newDate = firstDayOfPreviousWeek(from: july15)
print(newDate ?? "Could not retrieve a date") // prints 2010-07-05 00:00:00 +0000
于 2016-12-17T16:27:55.277 に答える