取当前时间并从中减去3个小时

Question

想知道如何获取当前时间,并从中减去3小时存储在NSString中？

Answer 1

NSDate *now = [NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps = [[NSDateComponents alloc] init];
[comps setHour:-3];
NSDate *threeHoursAgo = [calendar dateByAddingComponents:comps toDate:now options:0];
[comps release];
[calendar release];

我把输出留给NSString你(使用NSDateFormatter).