核心数据与多个实体和uitableview

Question

我创建了一个核心数据模型，它有三个实体，称为Customer，Form1和Form2。我已经建立了从客户到form1和form2的反向关系，反之亦然。所以当创建一个新客户时，需要为该客户创建form1和form2。我遇到的问题是在客户被删除后，为每个客户访问正确的form1或form2。那么，我如何正确地添加和删除所有三个实体中的对象。让我知道如果我以正确的方式做所有事情，因为我以前从来没有在多个实体中工作过，并且在可用视图中工作过。任何帮助将是伟大的！

-(void) viewDidLoad 
{ 
// Generate a fetch request for reading from the database and set its entity property 
NSFetchRequest *request = [[NSFetchRequest alloc] init]; 
NSEntityDescription *entity = [NSEntityDescription entityForName: @"Customer" inManagedObjectContext: managedObjectContext]; 
request.entity = entity; 
[entity release]; 

// Perform the actual fetch from the permanent store and initialize the menuItems array with the results 
NSError *error = nil; 

customerArray = [[managedObjectContext executeFetchRequest: request error: &error] 

[request release]; 
} 




- (void) addItem 
{ 
// Insert a new record in the database 
Customer * customerItem = [NSEntityDescription insertNewObjectForEntityForName: @"Customer" inManagedObjectContext: managedObjectContext]; 
NSError *error = nil; 

// Insert a new item in the table's data source 
[customerArray insertObject: customerItem atIndex: 0]; 

[NSEntityDescription insertNewObjectForEntityForName: @"Form1" inManagedObjectContext: managedObjectContext]; 

[NSEntityDescription insertNewObjectForEntityForName: @"Form2" inManagedObjectContext: managedObjectContext]; 
[managedObjectContext save: &error]; 

// Insert a new row in the table 
NSIndexPath *indexPath = [NSIndexPath indexPathForRow: 0 inSection: 0]; 
[table insertRowsAtIndexPaths: [NSArray arrayWithObject: indexPath] withRowAnimation: UITableViewRowAnimationFade]; 
} 

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    if (editingStyle == UITableViewCellEditingStyleDelete) 
{ 
    // Delete item from the context and save the context. This removes the item from the permanent store. 
    [managedObjectContext deleteObject: [customerArray objectAtIndex: indexPath.row]]; 
    NSError *error = nil; 
    [managedObjectContext save: &error]; 

    // Remove the item from the table's data source array 
    [customerArray removeObjectAtIndex: indexPath.row]; 

    // Delete the item from the table itself. 
    [tableView deleteRowsAtIndexPaths: [NSArray arrayWithObject: indexPath] withRowAnimation: YES]; 
} 

} 

Answer 1

正如您从客户到form1 & form2。您可以从客户那里访问form1 & form2。

Raywinderlich有一个nice tutorial用于演示关系核心数据，以相同的方式执行。