包含原始日期的一周中的工作日的日期

Question

我想要包含原始日期的Weekday=星期五的日期

我尝试过以下编码，但它不起作用：-

Nsdate currDate;(currDate can be date)
int dayofweek; // Detect the day of week
NSString *Start_date = @"13/nov/2014";
                    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
                    [formatter setDateFormat:@"yyyy-MM-dd"];
                    NSString *stringFromDate = [formatter stringFromDate:currDate];
 NSCalendar* cal = [NSCalendar currentCalendar];
NSDateComponents* comp = [cal components:NSWeekdayCalendarUnit fromDate:Startdate]; dayofweek=[comp weekday];
 NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
                            [dateFormatter setDateFormat:@"yyyy-MM-dd"];
 NSDate *Startdate = [[NSDate alloc] init];
Startdate = [dateFormatter dateFromString:Start_date];
NSDate *fetchdate=[self firstDayOfWeekFromDate:Startdate];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"yyyy-MM-dd"];
NSString *stringFromDate1 = [formatter stringFromDate:fetchdate];
NSString *trimmedString=[stringFromDate1 substringFromIndex:MAX((int)[stringFromDate1 length]-2, 0)];
NSString *trimmedString1=[stringFromDate substringFromIndex:MAX((int)[stringFromDate1 length]-2, 0)];
if([trimmedString1 isEqualToString:trimmedString]){
     NSlog(@"YES IT IS DAY OF WEEK");
}

//***************************function
- (NSDate *)firstDayOfWeekFromDate:(NSDate *)date {
    NSCalendar* calendar = [NSCalendar currentCalendar];
    NSDateComponents* comps = [calendar components:NSYearForWeekOfYearCalendarUnit |NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:date];
    [comps setWeekday:dayofweek]; // 2: monday
    return [calendar dateFromComponents:comps];
}

Answer 1

将其分解为多个步骤。绝对没有理由在一个函数中完成所有操作。

我想你明年也想要同一个星期五。（来自您删除的最后一个问题）

首先，你需要在一年内得到相同的日期。

- (NSDate *)dateOneYearFromDate:(NSDate *)date
{
    NSDateComponents *components = [NSDateComponents new];
    components.year = 1;
    NSCalendar *calendar = [NSCalendar currentCalendar];
    return [calendar dateByAddingComponents:components toDate:date options:0];
}

然后你需要计算出日期是哪一天…

- (NSInteger)dayOfWeekFromDate:(NSDate *)date
{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *components = [calendar components:NSWeekdayCalendarUnit fromDate:date];
    return components.weekday;
}

然后你需要找到从那个日期开始的星期五。。。

- (NSDate *)fridayFromWeekOfDate:(NSDate *)date
{
    NSInteger friday = 6;
    NSInteger dayOfWeekFromDate = [self dayOfWeekFromDate:date];
    NSInteger difference = friday - dayOfWeekFromDate;
    NSDateComponents *components = [NSDateComponents new];
    components.day = difference;
    NSCalendar *calendar = [NSCalendar currentCalendar];
    return [calendar dateByAddingComponents:components toDate:date options:0];
}

让每一步都成为一小步。。。

现在你可以这样做了。。。

- (void)someFunction
{
    NSDate *someFriday = // this is your original date...
    NSDate *oneYearLater = [self dateOneYearFromDate:someFriday];
    NSDate *fridayOneYearFromNow = [self fridayFromWeekOfDate:oneYearLater];
}

Answer 2

下面的代码应该会让您开始。。。（编码盲/未测试）

NSDate * currentDate = [NSDate date];
CFAbsoluteTime at = CFAbsoluteTimeGetCurrent();
CFTimeZoneRef tz = CFTimeZoneCopySystem();
SInt32 WeekdayNumber = CFAbsoluteTimeGetDayOfWeek(at, tz);
int currentDayOfTheWeek = (int)WeekdayNumber;
if(currentDayOfTheWeek == 5) {
    //Its Friday!
    return currentDate;
} else {
    return [currentDate dateByAddingTimeInterval:((60 * 60 * 24) * (5 - currentDayOfTheWeek)]; 
}