NSDate

获取当前时间

-(NSString*)getCurrentTimestamp{

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];

// ----------设置你想要的格式,hh与HH的区别:分别表示12小时制,24小时制

[formatter setDateFormat:@"YYYY-MM-dd HH:mm:ss"];

//现在时间,你可以输出来看下是什么格式

NSDate *datenow = [NSDate date];

//----------将nsdate按formatter格式转成nsstring

NSString *currentTimeString = [formatter stringFromDate:datenow];

NSLog(@"currentTimeString =  %@",currentTimeString);

return currentTimeString;

}

两个时间进行比较

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];

[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];

  NSDate *lastHourDate = [dateFormatter dateFromString:lastHour];

NSDate *currentTimeDate = [dateFormatter dateFromString:[self getCurrentTimestamp]];

NSCalendar *calendar = [NSCalendar currentCalendar];

NSCalendarUnit type = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;

 NSDateComponents *cmps = [calendar components:type fromDate:lastHourDate toDate:currentTimeDate options:0];

NSLog(@"两个时间相差%ld年%ld月%ld日%ld小时%ld分钟%ld秒", cmps.year, cmps.month, cmps.day, cmps.hour, cmps.minute, cmps.second);