如何获取NSManagedObjectId和检索数据

Question

我有一个名为TableViewController的HomeTableViewController，它装载了来自Core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);

我得到了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，我希望得到与所选单元格相等的对象，并访问它的布尔值"Paid“。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");
}

尽管当我运行应用程序时，Found永远都不等于是。这意味着我的对象Id不匹配。我想知道如何找到所选的表视图单元格，从其中获取NSManagedObjectId，然后访问它的属性。

所有的帮助都很感激，谢谢。

Answer 1

您正在遍历数组，但不要实际将OwedId更改为正在数组中查看的项。这应该是可行的：

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");
}

Answer 2

我认为问题在第9行。

if(OweID == moID)

可能已更改了托管对象的ID对象(而不是ID信息本身)。使用==只比较引用。试着使用

if([OweID isEqual::moID])

托马斯