Question

我希望过去7天（例如FRI，THU，WED，TUE，MON，SUN，SAT，FRI）在系统当前日期的数组中。如果有人有任何想法，请帮助。帮助将不胜感激。谢谢你非常喜欢

Answer 1

我的两分钱：

NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateFormat:@"EEE"];

NSDate *now = [NSDate date];

NSMutableArray *results = [NSMutableArray arrayWithCapacity:8];

for (int i = 0; i < 8; i++)
{
    NSDate *date = [NSDate dateWithTimeInterval:-(i * (60 * 60 * 24)) sinceDate:now];
    [results addObject:[dateFormatter stringFromDate:date]];
}

NSLog(@"%@", results);

通过这种方式，您可以获得本地化的工作日名称，而无需自己构建数组。

实际上，它可以为您提供您所要求的内容。

Answer 2

哈哈，你在我做其他一些事情的时候得到了很多答案，但是因为我大部分已经完成了，所以无论如何都是这样。这种方法甚至适用于时间变化等，并提供本地化的日期名称。（如果您正在减去许多其他示例中的时间值，那么如果您接近时间变化，则会在时间发生变化时遇到问题....）

// Subtract one day from the current date (this compensates for daylight savings time, etc, etc.)
- (NSDate *)dateBySubtractingOneDayFromDate:(NSDate *)date {
    NSCalendar *cal = [NSCalendar currentCalendar];

    NSDateComponents *minusOneDay = [[NSDateComponents alloc] init];
    [minusOneDay setDay:-1];
    NSDate *newDate = [cal dateByAddingComponents:minusOneDay 
                                           toDate:date 
                                          options:NSWrapCalendarComponents];
    return newDate;
}

- (NSArray *)lastSevenDays {
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"EEE"];

    NSDate *date = [NSDate date];
    NSMutableArray *weekDays = [[NSMutableArray alloc] initWithCapacity:8];
    for (int i = 0; i > -8; i--) {
        NSString *weekDay = [formatter stringFromDate:date];
        [weekDays addObject:weekDay];
        date = [self dateBySubtractingOneDayFromDate:date];
    }
    return weekDays;
}


// To use it, do this:
NSLog(@"%@", [self lastSevenDays]);
/* 
 * Results:
 * (
 *     Fri,
 *     Thu,
 *     Wed,
 *     Tue,
 *     Mon,
 *     Sun,
 *     Sat,
 *     Fri
 * )
 * 
 */

Answer 3

我假设这是一个通用的编程问题，并不是特定于iOS环境。如果我的假设不正确，请随意忽略这个答案。

构建一个包含星期几的数组。找到今天的索引，在数组上向后循环，将内容复制到您正在创建的数组，当您将零设置为6时（假设基于零的数组）并循环回到今天的星期几。

像这样（这段代码是名义上的）：

string[] days = {"Mon", "Tues" .... "Sun"};
string[] last8Days = new string[8];
int daysIndex, last8DaysIndex;
daysIndex = \\some code to get the index of today's day.
for (last8DaysIndex = 0; last8DaysIndex < 8; last8DaysIndex++)
{
   last8Days[last8DaysIndex] = days[daysIndex];
   daysIndex--;
   if(daysIndex < 0)
       daysIndex = 6;
}

希望这有帮助。

Answer 4

我认为这篇StackOverflow帖子最有用：

How to check what day of the week it is (i.e. Tues, Fri?) and compare two NSDates?

请参阅 CanBerkGüder的回答，它可以帮助您如何获得星期几：

您可以使用NSDateComponents：

unsigned units = NSYearCalendarUnit | NSMonthCalendarUnit |   NSDayCalendarUnit; NSCalendar * gregorian = [[NSCalendar alloc]   initWithCalendarIdentifier：NSGregorianCalendar]; NSDateComponents   * components = [gregorian components：units fromDate：date];那么您可以像这样访问日期的各个部分：

[组件年份]; [组件月]; [组件日];或者，你可以   使用NSCalendar的dateFromComponents构造一个新的NSDate对象   方法，并比较两个NSDate对象。

另请参阅下面的这篇文章，因为它可以帮助您如何从当前日期获得过去7天的逻辑：

get NSDate today, yesterday, this Week, last Week, this Month, last Month... variables

参考 Ben S ：

的回答

改编自Date and Time Programming Guide：

// Right now, you can remove the seconds into the day if you want
NSDate *today = [NSDate date];

// All intervals taken from Google
NSDate *yesterday = [today dateByAddingTimeInterval: -86400.0];
NSDate *thisWeek  = [today dateByAddingTimeInterval: -604800.0];
NSDate *lastWeek  = [today dateByAddingTimeInterval: -1209600.0];

// To get the correct number of seconds in each month use NSCalendar
NSDate *thisMonth = [today dateByAddingTimeInterval: -2629743.83];
NSDate *lastMonth = [today dateByAddingTimeInterval: -5259487.66];

如果您想要正确的天数，具体取决于月份你应该使用NSCalendar。

此外，你可以通过 hasnat 在同一篇文章中引用同样好的答案：

可能是一个更好的方式来写这个，但在这里我想出了Ben的 NSCalendar建议并从那里开始工作到NSDateComponents

NSCalendar *cal = [NSCalendar currentCalendar];
NSDateComponents *components = [cal components:( NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit ) fromDate:[[NSDate alloc] init]];

[components setHour:-[components hour]];
[components setMinute:-[components minute]];
[components setSecond:-[components second]];
NSDate *today = [cal dateByAddingComponents:components toDate:[[NSDate alloc] init] options:0]; //This variable should now be pointing at a date object that is the start of today (midnight);

[components setHour:-24];
[components setMinute:0];
[components setSecond:0];
NSDate *yesterday = [cal dateByAddingComponents:components toDate: today options:0];

components = [cal components:NSWeekdayCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:[[NSDate alloc] init]];

[components setDay:([components day] - ([components weekday] - 1))]; 
NSDate *thisWeek  = [cal dateFromComponents:components];

[components setDay:([components day] - 7)];
NSDate *lastWeek  = [cal dateFromComponents:components];

[components setDay:([components day] - ([components day] -1))]; 
NSDate *thisMonth = [cal dateFromComponents:components];

[components setMonth:([components month] - 1)]; 
NSDate *lastMonth = [cal dateFromComponents:components];

NSLog(@"today=%@",today);
NSLog(@"yesterday=%@",yesterday);
NSLog(@"thisWeek=%@",thisWeek);
NSLog(@"lastWeek=%@",lastWeek);
NSLog(@"thisMonth=%@",thisMonth);
NSLog(@"lastMonth=%@",lastMonth);

希望这会对你有所帮助。

如何从当前日期开始在阵列中获得最近7天？

4 个答案: