Setting dynamic height for UITableViewCell with on

问题:

I have a UITableView whose cells will only contain images of variable heights, I set the row height dynamically according to image, it doesnt work perfectly, the images while scrolling sometimes get overlapped.Heres the code...

-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return [artistfeeds count];
}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 1;
}

-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell=[self.newsTableView dequeueReusableCellWithIdentifier:@"artistFeedCell"];

    UIImageView *imgView=[[UIImageView alloc]initWithImage:((ESArtistFeedObject*)[artistfeeds objectAtIndex:indexPath.section]).image];
    [cell.contentView addSubview:imgView];
    [cell.contentView sizeToFit];
    return  cell;
}

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    CGFloat height=((ESArtistFeedObject*)[artistfeeds objectAtIndex:indexPath.section]).image.size.height;
    NSLog(@"section: %i, image height: %f",indexPath.section,height);
    return height;
}

-(void)artistFeedFound:(NSNotification*)notification
{
    //NSLog(@"%@",[notification userInfo]);
    artistfeeds=[[NSMutableArray alloc]init];
    if([[[[notification userInfo]objectForKey:@"artistfeed"]objectForKey:@"artist"] isKindOfClass:[NSArray class]])
    {
        for(NSDictionary *tempDict in [[[notification userInfo]objectForKey:@"artistfeed"]objectForKey:@"artist"])
        {
            ESArtistFeedObject *artistFeed=[[ESArtistFeedObject alloc]init];
            artistFeed.name=[tempDict objectForKey:@"name"];
            artistFeed.type=[tempDict objectForKey:@"postType"];
            artistFeed.desc=[tempDict objectForKey:@"postDesc"];
            if(![artistFeed.type isEqualToString:@"photo"])
                artistFeed.image=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:@"http://c0364947.cdn2.cloudfiles.rackspacecloud.com/%@",[tempDict objectForKey:@"artist_image"]]]]];
            else
                artistFeed.image=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[tempDict objectForKey:@"photo"]]]];
            [artistfeeds addObject:artistFeed];
        }
    }
    [self.newsTableView reloadData];

}

Any suggestions?

回答1:

You're missing the code in cellForRowAtIndexPath that actually creates cells when there are none to reuse.

//assuming there is a class property `int cellImageTag = 100;`
-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell=[self.newsTableView dequeueReusableCellWithIdentifier:@"artistFeedCell"];
    UIImageView *imgView;
    if(cell == nil)
    {
      cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"artistFeedCell"];
      imgView = [[UIImageView alloc] init];
      imgView.tag = cellImageTag;
      [cell.contentView addSubview:imgView];
    }
    else
    {
      imgView = [cell.contentView viewWithTag:cellImageTag];
    }
    imgView.image = ((ESArtistFeedObject*)[artistfeeds objectAtIndex:indexPath.section]).image;
    [cell.contentView sizeToFit];
    return  cell;
}

edit: missed the comment about storyboards

edit2: I think this is caused by you creating and adding a new UIImageView subview every time you load a cell. I'm not sure how Storyboards handle re-use of cells but in general your class would have a tag ivar or constant to keep track of the tag of the views you want to re-use within the cells. Updating my code as an example.

edit3: The code that follows should be working for storyboards

//assuming there is a class property `int cellImageTag = 100;`
-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell=[self.newsTableView dequeueReusableCellWithIdentifier:@"artistFeedCell"];
    UIImageView *imgView = [cell.contentView viewWithTag:cellImageTag];
    if(!imgView)
    {
      imgView = [[UIImageView alloc] init];
      imgView.tag = cellImageTag;
      [cell.contentView addSubview:imgView];
    }
    imgView.image = ((ESArtistFeedObject*)[artistfeeds objectAtIndex:indexPath.section]).image;
    [cell.contentView sizeToFit];
    return  cell;
}