- (IBAction) startOrstop:(UIButton *)sender  {      //点击切换按钮背景图      UIImage *newImage = (checked) ? [UIImage imageNamed:@"red.png"] : [UIImage imageNamed:@"green.png"];      [leftBtn setBackgroundImage:newImage forState:UIControlStateNormal];            NSString *titlel = (checked) ? (@"Stop") : (@"Start");      [leftBtn setTitle:titlel forState:UIControlStateNormal];      NSString *titler = (checked) ? (@"Lap") : (@"Reset");      [rightBtn setTitle:titler forState:UIControlStateNormal];                  if (checked)   //start      {          timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(updateTime) userInfo:nil repeats:YES];      }else {        //stop          [timer invalidate];      }            checked = !checked;  }    - (IBAction) resetOrLap:(UIButton *)sender  {      static NSInteger count = 1;            if (checked) //reset      {          time = time_lap = 0.0;          timestr = [NSString stringWithFormat:@"00:00.0"];          [label setText:timestr];          list_time = list_lap = nil;          count = 1;          [tableview reloadData];                }else {      //lap          if (list_time == nil) {              list_time = [[NSArray alloc]initWithObjects:timestr_lap, nil];              list_lap = [[NSArray alloc]initWithObjects:[NSString stringWithFormat:@"%d",count++], nil];          }else {  #if 0              [list arrayByAddingObject:timestr];  #else              NSArray *array = [[NSArray alloc]initWithObjects:timestr_lap, nil];              list_time = [array arrayByAddingObjectsFromArray:list_time];              array = [[NSArray alloc]initWithObjects:[NSString stringWithFormat:@"%d",count++], nil];              list_lap = [array arrayByAddingObjectsFromArray:list_lap];  #endif          }          time_lap = 0;          [tableview reloadData];       }  }    - (float) updateTime  {      time+=0.1;      time_lap +=0.1;      timestr = [NSString stringWithFormat:@"d:.1f",(int)(time / 60) ,time - ( 60 * (int)( time / 60 ) )];      timestr_lap = [NSString stringWithFormat:@"d:.1f",(int)(time_lap / 60) ,time_lap - ( 60 * (int)( time_lap / 60 ) )];      [label setText:timestr];      return time;  }      - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section  {      return [list_time count];  }    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath  {      static NSString *tableViewIdentifier = @"tableViewIdentifier";      UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:tableViewIdentifier];      if (cell == nil) {          cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:tableViewIdentifier];       }            NSUInteger row = [indexPath row];            cell.detailTextLabel.text = [list_time objectAtIndex:row];      cell.detailTextLabel.textColor = [UIColor blackColor];      cell.detailTextLabel.font = [UIFont boldSystemFontOfSize:25.0];      cell.detailTextLabel.textAlignment = UITextAlignmentCenter;            NSString *text = [[NSString alloc]initWithFormat:@"lap %@", [list_lap objectAtIndex:row]];      cell.textLabel.text = text;      return cell;  }