【图】一个iOS上的秒表小应用的实现方法分享

模仿实现一下ios系统应用时钟里的秒表程序，就是这个应用：

主要实现的功能：
1.由start/stop键实现计时
2.有reset/lap键实现复位和计次

需要思考的点：
1.时间的表示方法（有很多种思路）
2.计次数据的倒序排列，即计次1的数据在最底端，依次向上为计次2，计次3的时间数据

我的实现：
ARC省去了我们自行管理内存的大部分事情，写惯了c++于是舒服了很多

代码如下：

- (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:@"%02d:%04.1f",(int)(time / 60) ,time - ( 60 * (int)( time / 60 ) )];
    timestr_lap = [NSString stringWithFormat:@"%02d:%04.1f",(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;
}