特定日期的个性化信息

Question

我在写报警应用程序。在应用程序中，用户可以随时选择日期来设置当天的闹钟。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

How to Get an NSDate for a Specific Day of Week and Time from an Existing NSDate - 本文将帮助你解决这个问题。您可以从当前周五得到的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，你可能要检查是否thisWeekFriday小于[NSDate date]，并获得下周五，如果它是。您可以将日期移动一周：

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

Answer 2

可以计算天数两个日期之间是这样的：

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