在一个表视图中显示两个实体

Question

我有一个自定义表格视图单元格。有两个标签。 右侧的标签从实体加载其文本。 （见下图）

-(void)viewWillAppear:(BOOL)animated{
if (self.context == nil)
{
    self.context = [(RootAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
}
NSFetchRequest *request = [[NSFetchRequest alloc]init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Entity" inManagedObjectContext:self.context];

[request setEntity:entity];
NSError *error;
NSMutableArray *array = [[self.context executeFetchRequest:request error:&error] mutableCopy];
[self setTableArray:array];
[self.myTableView reloadData];
[super viewWillAppear:YES];
}

我根据文档相应地设置了文本。

当我尝试从不同的实体加载第二个标签文本时，我的问题就在于，所以简单地说，我试过这个：

-(void)viewWillAppear:(BOOL)animated{
if (self.context == nil)
{
    self.context = [(RootAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
}
NSFetchRequest *request = [[NSFetchRequest alloc]init];
NSFetchRequest *sRequest = [[NSFetchRequest alloc]init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Entity" inManagedObjectContext:self.context];
NSEntityDescription *sEntity = [NSEntityDescription entityForName:@"Entity2" inManagedObjectContext:self.context];
[request setEntity:entity];
[sRequest setEntity:sEntity];
NSError *error;
NSError *sError;
NSMutableArray *array = [[self.context executeFetchRequest:request error:&error] mutableCopy];
NSMutableArray *sArray = [[self.context executeFetchRequest:sRequest error:&sError]mutableCopy];
[self setTableArray:array];
[self setSecondTableArray:sArray];
[self.ammoTable reloadData];
[super viewWillAppear:YES];
}

我通过以下方式设置表格View的单元格文本：

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

self.cell = [tableView dequeueReusableCellWithIdentifier:identifier];

Entity2 *entity2 = [self.secondTableArray objectAtIndex:indexPath.row];
Entity *entity = [self.tableArray objectAtIndex:indexPath.row];

self.cell.rightLabel.text = [[entity.brand stringByAppendingString:@" "] stringByAppendingString:entity.model];
self.cell.leftLabel.text = entity2.numberOfRounds;
return self.cell;
}

，当我推动这个观点时，我得到了这个错误：

*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array'

我在这一行收到SIGABRT错误：

Entity2 *entity2 = [self.secondTableArray objectAtIndex:indexPath.row];

非常感谢任何帮助，谢谢！

Answer 1

我没有尝试加载2个不同的实体，而只是在原始实体中添加了另一个属性，并导入/使用了实体中新创建的属性来填充正确的标签！