使用 objc_setAssociatedObject 为 UITableViewCell 传递 UIButton @selector 参数

Question

我正在尝试在这篇文章中实施一个建议：Pass an argument to selector 使用objc_setAssociatedObject 和objc_getAssociatedObject 在UITableViewCell 中将@selector 参数传递给UIButton。我对其进行编码的方式，它总是最终通过它创建/加载的最后一个单元格的行。这是我的代码：

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

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    UILabel *mainLabel;
    soundButton=[UIButton buttonWithType:UIButtonTypeCustom];

    if (cell == nil){

        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    soundButton.tag = 33;
        [soundButton addTarget:self action:@selector(soundButtonAction) forControlEvents:UIControlEventTouchUpInside];
        [soundButton setFrame:CGRectMake(210,3,68, 37)];

         [soundButton setBackgroundImage:[UIImage imageNamed:@"musicNote"] forState:UIControlStateNormal];

         [cell.contentView addSubview:soundButton];
    } else {

        soundButton = (UIButton *)[cell.contentView viewWithTag:33];
    }
    objc_setAssociatedObject(soundButton, "IndexPath", indexPath, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    return cell;
}

-(void)soundButtonAction
{
    NSIndexPath *ip = objc_getAssociatedObject(soundButton, "IndexPath");

Answer 1

看起来 soundButton 是你班上的 ivar？每次请求一个单元格时它都会被覆盖，所以你只会得到最后一个。

我也认为使用"IndexPath"作为key不是一个好主意。

static char indexPathKey; // use address of indexPathKey as key

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

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    UILabel *mainLabel;
    soundButton=[UIButton buttonWithType:UIButtonTypeCustom];

    if (cell == nil){

        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    soundButton.tag = 33;
        [soundButton addTarget:self action:@selector(soundButtonAction:) /*extra :*/ forControlEvents:UIControlEventTouchUpInside];
        [soundButton setFrame:CGRectMake(210,3,68, 37)];

         [soundButton setBackgroundImage:[UIImage imageNamed:@"musicNote"] forState:UIControlStateNormal];

         [cell.contentView addSubview:soundButton];
    } else {

        soundButton = (UIButton *)[cell.contentView viewWithTag:33];
    }
    objc_setAssociatedObject(soundButton, &indexPathKey, indexPath, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    return cell;
}

-(void)soundButtonAction:(UIButton *)sender
{
    NSIndexPath *ip = objc_getAssociatedObject(sender, &indexPathKey);