objective-c - 计算下一个生日日期

Question

NSDate从像这样的字符串计算（和创建）下一个生日的最简单方法是@"02/29/1980"什么？（日月年）

Answer 1

这是我将如何做到的。

请注意，在这种情况下，您选择的日期是闰日，因此结果将显示不是闰年的第二天。“正常”日期将显示新年的同一天。

NSString *birthdayString        = @"02/29/1980";

// Convert the string to a NSDate
NSDateFormatter *formatter      = [NSDateFormatter new];
formatter.timeZone              = [NSTimeZone timeZoneWithName:@"UTC"];
formatter.dateFormat            = @"MM/dd/yyyy";
NSDate *birthday                = [formatter dateFromString:birthdayString];

// Break the date apart into its components and change the year to the current year
NSCalendar *cal                 = [NSCalendar currentCalendar];
cal.timeZone                    = [NSTimeZone timeZoneWithName:@"UTC"];
NSDate *now                     = [NSDate date];
NSDateComponents *currentComps  = [cal components:NSYearCalendarUnit fromDate:now];
NSDateComponents *birthdayComps = [cal components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit
                                         fromDate:birthday];
birthdayComps.year              = currentComps.year;

// Create the date from the modified components
NSDate *birthdayDate            = [cal dateFromComponents:birthdayComps];

// Check to see if the birthday has passed yet this year, and if not add one year
if ([now compare:birthdayDate] == NSOrderedDescending)
{
    NSDateComponents *oneYear = [NSDateComponents new];
    oneYear.year = 1;
    birthdayDate = [cal dateByAddingComponents:oneYear toDate:birthdayDate options:0];
}

NSLog(@"Next Birthday: %@", birthdayDate);
// Results: Next Birthday: 2013-03-01

Answer 2

使用NSDateFormatter将字符串转换为日期。然后通过添加一年来添加一年。鲍勃是你的叔叔。

Answer 3

简单的方法（闰年被窃听）

 NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:NSDayCalendarUnit
                                                   fromDate:[NSDate date]
                                                     toDate:birthdate
                                                    options:0];

NSInterger daysLeft = components.day % 365;