使用objc_setAssociatedObject為UITableViewCell傳遞UIButton @selector參數

Question

我正在嘗試在本文中實現一個建議：使用objc_setAssociatedObject和objc_getAssociatedObject 將參數傳遞給選擇器，以將@selector參數傳遞給UITableViewCell的UIButton 。 按照我的編碼方式，它總是最終經過創建/加載的最后一個單元格所在的行。 這是我的代碼：

- (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

看起來soundButton是您班上的一個ivar？ 每次請求一個單元格時，它都會被覆蓋，因此您只會獲得最后一個單元格。

我也認為使用"IndexPath"作為鍵不是一個好主意。

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);