ios 获得今天凌晨 12 点

Question

NSDate *today = [NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[calendar setLocale:[NSLocale currentLocale]];
[calendar setTimeZone:[NSTimeZone timeZoneWithName:@"US/Central"]];

NSDateComponents *nowComponents = [calendar components:NSYearCalendarUnit | NSWeekCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit fromDate:today];

[nowComponents setHour:hour];
[nowComponents setMinute:0];
[nowComponents setSecond:0];

NSLog(@"%@", [calendar dateFromComponents:nowComponents]);

记录 2012-01-01 06:00:00 +0000。根据时区设置时间是正确的，但今天是 7 月 20 日...我做错了什么？

Answer 1

您需要提取年、月和日组件，并构造一个新的 NSDate，如下所示:

NSDate *today = [NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[calendar setLocale:[NSLocale currentLocale]];
[calendar setTimeZone:[NSTimeZone timeZoneWithName:@"US/Central"]];

NSDateComponents *nowComponents = [calendar components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:today];
today = [calendar dateFromComponents:nowComponents];

您不需要获取时间组件然后将它们设置回零:您可以将它们保持为默认值，方法是不首先要求提取它们。