iOS实现秒杀活动倒计时

@property (weak, nonatomic) IBOutlet UILabel *dayLabel;@property (weak, nonatomic) IBOutlet UILabel *hourLabel;@property (weak, nonatomic) IBOutlet UILabel *minuteLabel;@property (weak, nonatomic) IBOutlet UILabel *secondLabel;

//时间戳转换为日期格式(毫秒的时间戳)- (NSString *)timeWithTimeIntervalString:(NSString *)timeString{  // 格式化时间  NSDateFormatter* formatter = [[NSDateFormatter alloc] init];  formatter.timeZone = [NSTimeZone timeZoneWithName:@"shanghai"];  [formatter setDateStyle:NSDateFormatterMediumStyle];  [formatter setTimeStyle:NSDateFormatterShortStyle];  [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];  // 毫秒值转化为秒  NSDate* date = [NSDate dateWithTimeIntervalSince1970:[timeString doubleValue]/ 1000.0];  NSString* dateString = [formatter stringFromDate:date];  NSLog(@"时间 === %@",dateString);  return dateString;}-(void)downSecondHandle:(NSString *)aTimeString{  NSDateFormatter *dateFormatter=[[NSDateFormatter alloc] init];  [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];  NSDate *endDate = [dateFormatter dateFromString:[self timeWithTimeIntervalString:aTimeString]]; //结束时间  NSDate *endDate_tomorrow = [[NSDate alloc] initWithTimeIntervalSinceReferenceDate:([endDate timeIntervalSinceReferenceDate])];  NSDate *startDate = [NSDate date];    NSString* dateString = [dateFormatter stringFromDate:startDate];  NSLog(@"现在的时间 === %@",dateString);  NSTimeInterval timeInterval =[endDate_tomorrow timeIntervalSinceDate:startDate];  if (_timer==nil) {    __block int timeout = timeInterval; //倒计时时间    if (timeout!=0) {      dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);      _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,queue);      dispatch_source_set_timer(_timer,dispatch_walltime(NULL, 0),1.0*NSEC_PER_SEC, 0); //每秒执行      dispatch_source_set_event_handler(_timer, ^{        if(timeout<=0){ //倒计时结束，关闭          dispatch_source_cancel(_timer);          _timer = nil;          dispatch_async(dispatch_get_main_queue(), ^{            self.dayLabel.text = @"";            self.hourLabel.text = @"00";            self.minuteLabel.text = @"00";            self.secondLabel.text = @"00";          });        }else{          int days = (int)(timeout/(3600*24));          if (days==0) {            self.dayLabel.text = @"";          }          int hours = (int)((timeout-days*24*3600)/3600);          int minute = (int)(timeout-days*24*3600-hours*3600)/60;          int second = timeout-days*24*3600-hours*3600-minute*60;          dispatch_async(dispatch_get_main_queue(), ^{            if (days==0) {              self.dayLabel.text = @"0天";            }else{              self.dayLabel.text = [NSString stringWithFormat:@"%d天",days];            }            if (hours<10) {              self.hourLabel.text = [NSString stringWithFormat:@"0%d",hours];            }else{              self.hourLabel.text = [NSString stringWithFormat:@"%d",hours];            }            if (minute<10) {              self.minuteLabel.text = [NSString stringWithFormat:@"0%d",minute];            }else{              self.minuteLabel.text = [NSString stringWithFormat:@"%d",minute];            }            if (second<10) {              self.secondLabel.text = [NSString stringWithFormat:@"0%d",second];            }else{              self.secondLabel.text = [NSString stringWithFormat:@"%d",second];            }          });          timeout--;        }      });      dispatch_resume(_timer);    }  }}

[self downSecondHandle:@"1494622800000"];