DetailViewController 在创建新对象时不显示

Posted 2023-03-04

【中文标题】DetailViewController 在创建新对象时不显示

【英文标题】：DetailViewController not showing when creates new object

【发布时间】：2012-01-01 22:49:03

【问题描述】：

小伙伴们快速提问... IBAction 按钮正在创建一个新对象，但是当导航器按下 DetailViewController 时，它给了我 SIGABRT。 现在我想知道我是否不能在那里使用导航控制器功能。 以下代码无法正常工作

- (IBAction)insertNewObject

// Create a new instance of the entity managed by the fetched results controller.
NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];

Event *newEvent = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];
DetailViewController *detailController = [[[DetailViewController alloc] init] autorelease];

[newEvent setValue:[NSDate date] forKey:@"timeStamp"];

// Save the context with the new object.
NSError *error = nil;
if (![context save:&error]) 
    //improve this
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();


[detailController setEvent:newEvent];

NSLog(@"Detail Controller New Event 1 (from Master) : %@", newEvent);

[self.navigationController pushViewController:detailController animated:YES];

现在，当我选择单元格时，它可以完美运行。所以下面的代码有效：

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

if ([[segue identifier] isEqualToString:@"selectSegue"]) 
    NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];

    Event *event = (Event *)[fetchedResultsController objectAtIndexPath:indexPath];
    NSLog(@"Event on Master:: %@", event);

    DetailViewController *detailvc = [[[DetailViewController alloc] init] autorelease];

    detailvc.event = [self.fetchedResultsController objectAtIndexPath:indexPath];
    NSLog(@"Event on Detail when created :: %@", detailvc.event);

    if (event) [[segue destinationViewController] setEvent:(Event *) [self.fetchedResultsController objectAtIndexPath:indexPath]];  //was: setDetailItem:selectedObject
    [event release];
    [detailvc.event retain];

感觉好像我错过了一些简单的东西。但是任何人都可以帮我将对象添加到该 DetailViewController 而不获得 SIGABRT 吗？ 谢谢大家，新年快乐。

【参考方案1】：

您的代码似乎一切正常。 根据我的经验，您应该检查是否为实体设置了所有强制属性。因为在某些情况下，错误语句并不介意这个错误！

【讨论】：

所有属性都标记为可选。我认为故事板让我感到困惑。现在有很多方法可以推送视图控制器。但是感谢您迄今为止的帮助。