UITableView 和 Cell Reuse [英] UITableView and Cell Reuse

问题描述

我有一个 UITableView 并且我已经子类化了 UITableViewCell(称为 CustomCell)，所以它有几个标签和一个 UIImageView.

I have a UITableView and I've subclassed UITableViewCell (called it CustomCell) so it has several labels and a UIImageView.

只有某些单元格会实际显示图像.这是我的 tableView:cellForRowAtIndexPath::

Only certain cells will actually display an image. Here's my code for tableView:cellForRowAtIndexPath::

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

    Match *aMatch = [[appDelegate.matchByDate objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];
    static NSString *CellIdentifier = @"Cell";


    CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[CustomCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease];
    }


    cell.homeLabel.text = aMatch.homeTeam;
    cell.awayLabel.text = aMatch.awayTeam;
    cell.timeLabel.text = aMatch.koTime;
    cell.tournamentLabel.text = aMatch.tournament;


    NSString *tempString = [appDelegate.teamLogos objectForKey:[aMatch homeTeam]];
    if (tempString!=nil) {
        cell.homeImageView.image = [UIImage imageNamed:tempString];
    }

    return cell;
}

所以它只在我设置的字典中找到相应的图像时才设置 homeImageView.这似乎适用于前几个单元格，但如果我滚动列表，我会发现单元格有一个图像，而它们不应该有图像.

So it only sets the homeImageView when it finds a corresponding image in a dictionary I have set up. This seems to work for the first few cells, but if I scroll through the list I find cells have an image when they shouldn't have one.

我知道这可能是因为单元格被重用，但我在单元格被创建/重用后设置了 homeImageView?！

I understand this is probably because of the cell being re-used, but I'm setting the homeImageView after the cell has been created/reused?!

这是我的 CustomCell 类中的 init 方法

Here's the init method from my CustomCell Class

    - (id)initWithStyle:(UITableViewCellStyle)style
    reuseIdentifier:(NSString *)reuseIdentifier
{
    if (self = [super initWithStyle:style reuseIdentifier:reuseIdentifier]) {
        // Initialization code
        tournamentLabel = [[UILabel alloc] init];
        tournamentLabel.textAlignment = UITextAlignmentCenter;
        tournamentLabel.font = [UIFont systemFontOfSize:12];
        tournamentLabel.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0];  
        tournamentLabel.textColor = [UIColor darkGrayColor];
        homeLabel = [[UILabel alloc]init];
        homeLabel.textAlignment = UITextAlignmentLeft;
        homeLabel.font = [UIFont systemFontOfSize:16];
        homeLabel.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0];
        awayLabel = [[UILabel alloc]init];
        awayLabel.textAlignment = UITextAlignmentRight;
        awayLabel.font = [UIFont systemFontOfSize:16];
        awayLabel.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0];
        timeLabel = [[UILabel alloc]init];
        timeLabel.textAlignment = UITextAlignmentCenter;
        timeLabel.font = [UIFont systemFontOfSize:30];
        timeLabel.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0];
        timeLabel.textColor = [UIColor darkGrayColor];
        homeImageView = [[UIImageView alloc]init];
        awayImageView = [[UIImageView alloc]init];


        [self.contentView addSubview:homeLabel];
        [self.contentView addSubview:awayLabel];
        [self.contentView addSubview:timeLabel];
        [self.contentView addSubview:tournamentLabel];
        [self.contentView addSubview:homeImageView];
        [self.contentView addSubview:awayImageView];

    }
    return self;
}

推荐答案

如果你没有要显示的图像，你必须清除图像视图:

You have to clear the image view if you have no image to display:

...
if (tempString!=nil) {
    cell.homeImageView.image = [UIImage imageNamed:tempString];
} else {
    cell.homeImageView.image = nil;
}
...

这篇关于UITableView 和 Cell Reuse的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！