特定日期的通知

Question

我正在写一个闹钟应用程序。在应用程序中，用户可以选择在当天设置闹钟的天数。但我不知道在一周内的特定日期设置UILocalNotification。

我如何知道重复间隔。我知道我必须设置

如何计算星期五会有多少天？

Answer 1

您可以计算两个日期之间的天数，如下所示：

NSDateComponents *dateComponents = [[NSCalendar currentCalendar] components:NSDayCalendarUnit
                                                                   fromDate:today
                                                                     toDate:futureDate
                                                                    options:0];
NSInteger daysBetweenDates = dateComponents.day;

Answer 2

How to Get an NSDate for a Specific Day of Week and Time from an Existing NSDate - 本文将帮助您解决此问题。您可以从当前星期五获得NSDate：

NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setLocale:[NSLocale currentLocale]];
 
NSDateComponents *nowComponents = [gregorian components:NSYearCalendarUnit | NSWeekCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit fromDate:today];
 
[nowComponents setWeekday:6];
[nowComponents setWeek: [nowComponents week]]; // Current week
[nowComponents setHour:8]; // 8a.m.
[nowComponents setMinute:0];
[nowComponents setSecond:0];
 
NSDate *thisWeekFriday = [gregorian dateFromComponents:nowComponents];

然后，您可能想要检查thisWeekFriday是否小于[NSDate date]，如果是，请查看下周五。您可以使用以下日期将日期移动一周：

NSDateComponents *components = [[NSDateComponents alloc] init];
components.week = 1;
NSDate *nextWeekFriday = [gregorian dateByAddingComponents:components toDate:thisWeekFriday options:0];