ios - 如何获取 NSManagedObjectId 并检索数据

Question

我有一个名为 HomeTableViewController 的 TableViewController，它加载了来自 Core Data 数组的数据。我试图从选定的单元格中获取对象 ID，如下所示:

//Fetch Entity

NSManagedObjectContext *context = [self managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"OwedMoney"];

//Create an array that stores the contents of that entity

youOweArray = [[context executeFetchRequest:fetchRequest error:nil] mutableCopy];

//Create managedObjectId

NSManagedObject *YouOweData  = [youOweArray objectAtIndex:0];
NSManagedObjectID *moID = [YouOweData objectID];

//Successfully got the managedObjectId

NSLog(@"This is the id %@", moID);

我能够获得 managedObjectId。但困难的部分来了。现在我想遍历我的数组并获取所有对象。然后我想获取等于所选单元格的对象并访问它的 bool 值“付费”。我是这样做的:

 BOOL Found =  NO;
OwedMoney *OwedObject;
NSManagedObjectID *OwedId = [OwedObject objectID];

for (OwedMoney *OwedObject in youOweArray)
{

    NSLog(@"%@", OwedObject);
    if (OwedId == moID)
    {
        Found = YES;
        break;
    }

}

if (Found == YES)
{

BOOL isPaid = YES;
OwedMoney *Object = OwedObject;
Object.paid = [NSNumber numberWithBool:isPaid];

NSLog(@"Is it paid: %@",Object.paid? @"Yes":@"No");
}

虽然当我运行应用程序时，Found 永远不会等于 YES。这意味着我的对象 ID 不匹配。我想知道如何找到选定的表格 View 单元格，从中获取 NSManagedObjectId，然后访问它的属性。

感谢所有帮助，提前致谢。

Answer 1

您正在遍历数组，但从未真正将 OwedId 更改为您在数组中查看的项目。这应该有效:

BOOL Found =  NO;
OwedMoney *Object;


for (OwedMoney *OwedObject in youOweArray)
{
    NSManagedObjectID *OwedId = [OwedObject objectID];

    NSLog(@"%@", OwedObject);
    if (OwedId == moID)
    {
        Found = YES;
        Object = OwedObject;
        break;
    }

}

if (Found)
{

    BOOL isPaid = Found;
    Object.paid = [NSNumber numberWithBool:isPaid];

    NSLog(@"Is it paid: %@",Object.paid.boolValue? @"Yes":@"No");
}