UITableView单元格返回nil属性值 [英] UITableView cell returning nil property values

问题描述

我有以下内容:

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

    if(indexPath.row==0)
    {
        static NSString *CellID = @"FlourishCustomCell";
        FlourishCustomCell *cell = (FlourishCustomCell *) [tableView dequeueReusableCellWithIdentifier:CellID];
        if (cell == nil) {
            cell = [[[FlourishCustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellID] autorelease];
            cell.frame = CGRectMake(0, 0.0, 292.0, 30);
        }

        id <NSFetchedResultsSectionInfo> sectionInfo = 
        [[appDelegate.fetchedResultsController sections] objectAtIndex:indexPath.section];
        NSLog(@"DATE:%@", [sectionInfo name]); //Output: March 25

        cell.dateLabel.text=[sectionInfo name];
        NSLog(@"header cell:%@", cell.dateLabel.text); //Output:header cell:(null)

        return cell;
    }
    else {
        static NSString *CellIdentifier = @"IdeaCustomCell";
        IdeaCustomCell *cell = (IdeaCustomCell *) [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
        if (cell == nil) {
            cell = [[[IdeaCustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
            cell.frame = CGRectMake(0, 0.0, 292.0, 70);
        }

        [self configureCell:cell atIndexPath:[self newIndexPathForIndexPath:indexPath]];
        return cell;
    }
}

对于else部分(IdeaCustomCell)，单元格显示并可以正常工作，但是由于某些极其令人沮丧的原因，当我设置FlourishCell的dateLabel，然后立即尝试访问该值时，即使设置了它，我也得到一个null值！并且该单元格不会显示在屏幕上.

The cells display and work fine for the else part (the IdeaCustomCell), but for some extremely frustrating reason, when I set the dateLabel of the FlourishCell, and then immediately try to access that value, I get a null value, even though I just set it! And the cell doesn't display on screen.

我尝试覆盖FlourishCustomCell类中dateLabel的setter方法，并在其中放置了NSLog语句，但是由于某种原因它从未被调用.

I tried overriding the setter method for dateLabel in the FlourishCustomCell class, and I put an NSLog statement there, but it never gets called for some reason.

我完全不知道是什么原因造成的.我的意思是我当时和那里都在分配，但它仍然给我空值.有什么想法吗?

I have absolutely no idea what could be causing this. I mean I'm allocating right then and there, but it's still giving me null. Any ideas?

推荐答案

您需要初始化标签

解决方案1:用代码初始化单元格

Solution 1: Initializing cell in code

@interface FlourishCustomCell : UITableViewCell

@property (nonatomic, retain) UILable * dateLabel;

@end

@implementation FlourishCustomCell
@synthesize dateLabel = _dateLabel;

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
   if (self = [super initWithStyle:style reuseIdentifier:reuseIdentifier])
   {
      _dateLabel = [[UILabel alloc] initWithFrame:CGRectMake(0,0,300,50)];
      [self.contentView addSubview:_dateLabel]
   }

   return self; 
}

@end

解决方案2:从笔尖初始化细胞

Solution 2: Initializing cell from nib

@interface FlourishCustomCell : UITableViewCell

@property (nonatomic, retain) UILable * dateLabel;

@end

@implementation FlourishCustomCell
@synthesize dateLabel = _dateLabel;

- (id)init
{
self = [[[[NSBundle mainBundle] loadNibNamed:@"YOUR_NIB_NAME" owner:nil options:nil] 
         lastObject] 
        retain];

   return self;
}

@end

编辑:糟糕，忘记返回自己的init方法，更新了答案

EDIT: oops, forgot to return self on init method, updated the answer

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