cellForRowAtIndexPath返回nil [英] cellForRowAtIndexPath returns nil

问题描述

我正在尝试从表格视图中获取特定的单元格，以便我可以更改其标签并停止活动指示器.

I'm trying to get a specific cell from a table view so I can change it's label and stop the activity indicator.

我遇到的问题是cellForRowAtIndexPath返回nil.

The problem I'm having is that cellForRowAtIndexPath returns nil.

我的表格视图只有1行.

My table view has only 1 row.

代码:

- (id) initWithNibName: (NSString*) nibNameOrNil bundle: (NSBundle*) nibBundleOrNil
{
    self = [super initWithNibName: nibNameOrNil bundle: nibBundleOrNil];

    if (self) 
    {
        numberOfRows = 1;
    }

    return self;
}

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

-(void) stopCellIndicator
{

    LiveUserFeedCell* cell = (LiveUserFeedCell*)[self.liveFeed cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]];  
    [cell.activityIndicator stopAnimating];
    cell.middleLabel.text = @"N/a";
}

- (UITableViewCell*) tableView: (UITableView*) tableView cellForRowAtIndexPath: (NSIndexPath*) indexPath
{
    static NSString *CellIdentifier = @"UserFeedCell";


    LiveUserFeedCell *cell = (LiveUserFeedCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"LiveUserFeedCell" owner:self options:nil];
        cell = (LiveUserFeedCell *)[nib objectAtIndex:0];
    }

    [cell.imgView setImage:[TUNinePatchCache imageOfSize:cell.imgView.frame.size forNinePatchNamed:@"bg_home_newsfeed_normal"]];


    if (shouldDisplayLoading == NO)
    {
        NSArray* songs = homeScreen.recentPlaybacks.songs;
        TWSong* song = [songs objectAtIndex:index];
        cell.middleLabel.text = @"";
        [cell.activityIndicator stopAnimating];

        UIFont *font = [UIFont fontWithName:@"Trebuchet MS" size:14];                       

        NSString* kText =[NSString stringWithFormat:@"<b>%@</b> is listening to %@ by %@",song.user,song.title,song.artist];

        for(int i = 14; i > 0; i=i-1)
        {
            // Set the new font size.
            font = [font fontWithSize:i];
            // You can log the size you're trying: NSLog(@"Trying size: %u", i);

            /* This step is important: We make a constraint box 
             using only the fixed WIDTH of the UILabel. The height will
             be checked later. */ 
            CGSize constraintSize = CGSizeMake(cell.isWatching.frame.size.width, MAXFLOAT);

            // This step checks how tall the label would be with the desired font.
            CGSize labelSize = [kText sizeWithFont:font constrainedToSize:constraintSize lineBreakMode:UILineBreakModeWordWrap];

            /* Here is where you use the height requirement!
             Set the value in the if statement to the height of your UILabel
             If the label fits into your required height, it will break the loop
             and use that font size. */
            if(labelSize.height <= cell.isWatching.frame.size.height)
                break;
        }



        cell.isWatching.font = font;
        cell.isWatching.text = [TTStyledText textFromXHTML:kText lineBreaks:YES URLs:YES];
        cell.isWatching.textAlignment = UITextAlignmentCenter;

        ++index;
        if (index == [songs count])
            index=0;

    }
    else
    {       
        [cell.activityIndicator startAnimating];
    }

    return cell;
}

但是，如果我做这样的事情，我会得到一个有效的单元格:

However, if I do something like this, I do get a valid cell:

NSArray *indexPaths = [NSArray arrayWithObjects: 
                       [NSIndexPath indexPathForRow:0 inSection:0],
                       nil];

numberOfRows = 0;
[self.liveFeed deleteRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationLeft];


numberOfRows = 1;
[self.liveFeed insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationRight];

LiveUserFeedCell* cell = (LiveUserFeedCell*)[self.liveFeed cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]];  
[cell.activityIndicator stopAnimating];
cell.middleLabel.text = @"N/a";

有什么办法解决这个问题吗? (也许默认的第一个单元格不在第0行的第0节中?)

Any idea how to fix this? (Maybe the default first cell isn't in row 0 section 0?)

推荐答案

显然，问题是我查询单元格时尚未配置tableView.

Apparently the problem was that the tableView was not configured yet when I queried the the cell.

这篇关于cellForRowAtIndexPath返回nil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！