Question

我的代码有点麻烦，我希望能在这里得到一些帮助

我有一个uitableview，在每个uitableviewcell中我放了一个单独的uislider。每个uislider，用作音乐播放的进度条。

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    UIButton *button = nil;
    UISlider *customSlider = nil;

    static NSString *CellIdentifier = @"cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];

        UIImage *image = [UIImage imageNamed:@"button_play.png"];
        button = [UIButton buttonWithType:UIButtonTypeCustom];
        CGRect frame = CGRectMake(340.0, 10.0, image.size.width, image.size.height);
        button.frame = frame;
        [button setBackgroundImage:image forState:UIControlStateNormal];
        [button addTarget:self action:@selector(playAudio:) forControlEvents:UIControlEventTouchUpInside];
        button.tag = 4;
        [cell.contentView addSubview:button];

        customSlider = [[UISlider alloc] initWithFrame:CGRectMake(10, 45, 456, 20)];    
        customSlider.minimumValue = 0.0;
        customSlider.maximumValue = 100.0;
        customSlider.continuous = YES;
        customSlider.tag = 3;
        customSlider.value = 0.0;
        [cell.contentView addSubview:customSlider];
    }

    else {
        customSlider = (UISlider *)[cell.contentView viewWithTag:3];
        button = (UIButton *)[cell.contentView viewWithTag:4];
    }
    return cell;
}


- (void) playAudio:(UIButton *)sender {


    UIButton *button = (UIButton *)[sender superview];
    UITableViewCell *currentCellTouched = (UITableViewCell *)[button superview];
    UITableView *currentTable = (UITableView *)[currentCellTouched superview];
    NSIndexPath *indexPath = [currentTable indexPathForCell:currentCellTouched];

    //currentCellPlaying type of UITableViewCell and accessible from the rest classe
    currentCellPlaying = currentCellTouched;

    NSURL *url = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:NSLocalizedString([listFilesAudio objectAtIndex:indexPath.row], @"") ofType:@"mp3"]];

    player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:nil];
    player.delegate = self;
    [player prepareToPlay];

    [(UISlider *)[currentCellTouched.contentView viewWithTag:3] setMaximumValue:[player duration]];
    [(UISlider *)[currentCellTouched.contentView viewWithTag:3] setValue:0.0];

    NSTimer *sliderTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateTime:) userInfo:nil repeats:YES];
    [player play];

}


- (void)updateTime:(NSTimer *)timer {
    [(UISlider *)[currentCellPlaying.contentView viewWithTag:3] setValue:player.currentTime];
}

当我发布单个游戏时，一切正常，进度条会更新。

我的问题是，当我向下/向上滚动桌面视图时，播放音乐的单元格消失，一旦我们回到播放音乐的单元格上，uislider就会回到0，并且不再更新。 ..（NSLOG确认我们仍然进入“updateTime”方法）

如果你有解决我问题的方法，我会很高兴看到它。

提前谢谢。

Answer 1

Otium的答案并不完全正确，但它的方向是正确的。 celle并不是完全相同的对象，但是（实际上你是这样实现的）通过滚动离开可见区域的单元格被重新用于显示其他对象，滚动到可见区域。因此，当播放音乐的单元格再次可见时，另一个滑块对象会在其中显示原始单元格。此外，currentCellPlaying对象（可能）不再显示或显示为另一个单元格。因此，当您更新viewWithTag:3时，您（有时）不会看到它。你应该做的是存储“indexCurrentPlaying”而不是单元格或滑块引用。使用该索引，您可以在cellForRowAt的末尾装饰单元格....并且您可以更新updateTime内该索引处的单元格的滑块。希望有所帮助。

编辑：

一些未经测试的代码应该有效（可能有一些修复，但它解释了这个想法，我认为）：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{
    UIButton *button = nil;
    UISlider *customSlider = nil;

    static NSString *CellIdentifier = @"cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) 
    {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];

        UIImage *image = [UIImage imageNamed:@"button_play.png"];
        button = [UIButton buttonWithType:UIButtonTypeCustom];
        CGRect frame = CGRectMake(340.0, 10.0, image.size.width, image.size.height);
        button.frame = frame;
        [button setBackgroundImage:image forState:UIControlStateNormal];
        [button addTarget:self action:@selector(playAudio:) forControlEvents:UIControlEventTouchUpInside];
        button.tag = 4;
        [cell.contentView addSubview:button];

        customSlider = [[UISlider alloc] initWithFrame:CGRectMake(10, 45, 456, 20)];    
        customSlider.minimumValue = 0.0;
        customSlider.maximumValue = 100.0;
        customSlider.continuous = YES;
        customSlider.tag = 3;
        customSlider.value = 0.0;
        [cell.contentView addSubview:customSlider];
    }
    else
    {
       customSlider = [cell viewWithTag:3];     
    }
    if([indexPath isEqual:currentPlayingIndexPath])
    {
       currentPlayingSlider = customSlider; 
       [self updateTime];
    } 
    else if(customSlider == currentPlayingSlider)
    {
       currentPlayingSlider = nil;  
    }
    return cell;
}


- (void) playAudio
{

    NSURL *url = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:NSLocalizedString([listFilesAudio objectAtIndex:currentPlayingIndexPath.row], @"") ofType:@"mp3"]];

    player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:nil];
    player.delegate = self;
    [player prepareToPlay];

    NSTimer *sliderTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateTime:) userInfo:nil repeats:YES];
    [player play];
}


- (void)updateTime:(NSTimer *)timer 
{
    [currentPlayingSlider setValue:player.currentTime];
}


- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
   currentPlayingIndexPath = indexPath;
   currentPlayingSlider = [cellForRowAtIndexPath: currentPlayingIndexPath]; 
   [self playAudio];    
}

小心NSIndexPath isEqual。似乎在不同版本的SDK（look here）中回答不同的问题...因为您只需要行，所以可以将其更改为currentPlayingIndexPath.row == indexPath.row

Answer 2

UItableView使用可出现的单元格，因此所有单元格基本上都是相同的对象。在cellForRowAtIndexPath方法中，您应该再次设置滑块的进度。

当我滚动时，uitableviewcell中的Uislider不再自动更新

2 个答案: