NSDateFormatter *formatter = [[NSDateFormatter alloc] init] ;
[formatter setDateStyle:NSDateFormatterMediumStyle];
[formatter setTimeStyle:NSDateFormatterShortStyle];
[formatter setDateFormat:@"YYYY-MM-dd HH:mm:ss:SSS"]; // 设置想要的格式,hh与HH的区别:分别表示12小时制,24小时制
//设置时区,这一点对时间的处理有时很重要
NSTimeZone *timeZone=[NSTimeZone timeZoneWithName:@"Asia/Shanghai"];
[formatter setTimeZone:timeZone];
NSDate *datenow = [NSDate date];
NSString *timeSp = [NSString stringWithFormat:@"%ld", (long)([datenow timeInt