objective-c - 核心数据崩溃 : Keypath Project not found in entity

Question

- (void)fetchResult
{
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"Project" ascending:YES];

    [request setEntity:self.entityDescription];
    [request setSortDescriptors:[NSArray arrayWithObject:sortDescriptor]];
    self.fetchResultController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:nil];

    NSError *fetchError = nil;
    BOOL success = [self.fetchResultController performFetch:&fetchError];
    if (success) {
        NSLog(@"fetched!");
    }
    else {
    NSLog(@"fetch fail!");
    }
}

entityDescription 和上下文在 viewDidLoad 方法中设置，如下所示:

AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
self.managedObjectContext = appDelegate.managedObjectContext;
self.entityDescription = [NSEntityDescription entityForName:@"Project" inManagedObjectContext:self.managedObjectContext];

崩溃信息:
* 由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因:“实体中未找到关键路径项目”

有人可以帮忙吗？;)

Answer 1

排序描述符中使用的键

[NSSortDescriptor sortDescriptorWithKey:@"Project" ascending:YES];

必须是 Core Data 实体的属性，而不是实体本身的名称。
所以你应该用一些属性替换排序描述符中的 @"Project"项目实体，例如 @"name" 。