Question

我知道这个问题一再被问到。 This post总结了一些常见原因，但没有一个适用于我：

我在搜索时看到的每个答案都有以下变化：1）tableView为nil 2）numberOfRowsInSection为0 3）tableView的委托/数据源未设置4）在错误的uiTableView上调用reloadTable。

该帖子的答案是在另一次调用reloadData之前没有显示tableView，这也不是我的情况。我的实际代码有点冗长，所以我只想粘贴我认为相关的部分。随意请我粘贴更多。请注意，competitorsTable已添加到故事板中的视图中。

@interface CartItemViewController : TrackedUIViewController <UITableViewDataSource, UITableViewDelegate>
//...
@end

@interface CartItemViewController ()
//...
@property (weak, nonatomic) IBOutlet UITableView *competitorsTable;
@end

@implementation CartItemViewController
- (void)viewDidLoad
{
    [super viewDidLoad];
    // ...
    NSAssert(self.competitorsTable, @"Competitor table should not be nil");
    self.competitorsTable.dataSource = self;
    self.competitorsTable.delegate = self;
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self updateCompetitors];
}

- (void)updateCompetitors
{
    MBProgressHUD *indicator = [MBProgressHUD showHUDAddedTo:self.hostView animated:YES];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        while (![self.product isLoaded]) {
            [NSThread sleepForTimeInterval:1];
        }
        [self.product loadCompetitorsPriceForConditionValue:self.conditionValue];
        NSDictionary *competitors = self.product.competitors[@(self.conditionValue)];
        dispatch_async(dispatch_get_main_queue(), ^{
            if (competitors) {
                if (competitors.count > 1) {
                    self.hostView.hidden = NO;
                    self.hostView.hostedGraph = [[CompetitorGraph alloc]initWithFrame:self.hostView.bounds Competitors:competitors];
                    NSAssert(!self.competitorsTable.hidden, @"Competitor table should not be hidden");
                    [self.competitorsTable reloadData];
                } else {
                    self.hostView.hidden = YES;
                }
            } else {
                self.hostView.hostedGraph = nil;
            }
            [indicator hide:YES];
        });

    });
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    NSDictionary *competitors = self.product.competitors[@(self.conditionValue)];
    if (competitors.count == 0) {
        NSLog(@"WARNING: %s returning 0", __PRETTY_FUNCTION__);
    } else {
        NSLog(@"Number of rows: %d", competitors.count);
    }
    return [self.product.competitors[@(self.conditionValue)] count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Sort names according to its price
    NSDictionary *competitors = self.product.competitors[@(self.conditionValue)];
    NSArray *names = [competitors.allKeys sortedArrayUsingComparator:^NSComparisonResult(id name1, id name2) {
        if ([competitors[name1] floatValue] > [competitors[name2] floatValue]) {
            return (NSComparisonResult)NSOrderedAscending;
        } else if ([competitors[name1] floatValue] < [competitors[name2] floatValue]) {
            return (NSComparisonResult)NSOrderedDescending;
        } else {
            return (NSComparisonResult)NSOrderedSame;
        }
    }];
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"vendor"];
    NSString *vendorName = names[indexPath.row];
    cell.textLabel.text = vendorName;
    cell.detailTextLabel.text = competitors[vendorName];
    return cell;
}

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

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    return @"Competitors' Offer";
}
@end

当打开视图时，有两个对numberOfRowsInSection的调用，一个返回0，这是正常的，因为竞争对手信息尚未加载，另一个返回大于0的数字。但是，没有一个调用cellForRowAtIndexPath例。

Answer 1

经过几个小时的调试，我终于找到了问题：我没有设置支柱和弹簧，使得表被挤压到0高度。因为未显示，所以未调用cellForRowAtIndexPath

另一个“reloadData调用numberOfRows，但不是cellForRowAtIndexPath”

1 个答案: