抱歉,如果我无法完美解释。 我有一个fetchResultController getter。
如下 -
- (NSFetchedResultsController *)fetchedResultsController
{
if (_fetchedResultsController != nil) {
return _fetchedResultsController;
}
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName: self.entityName inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
// Set the batch size to a suitable number.
[fetchRequest setFetchBatchSize:20];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:keyColumnNamePid ascending:NO];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
[fetchRequest setSortDescriptors:sortDescriptors];
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:@"myCache"];
self.fetchedResultsController = aFetchedResultsController;
self.fetchedResultsController.delegate = self;
// Perform Fetch on Result Controller
NSError *error = nil;
if (![self.fetchedResultsController performFetch:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
return _fetchedResultsController;
}
现在我想设置fetchRequest的一些谓词和属性。(仅当它需要时。) 我的意思是我做了另一种方法 -
-(NSFetchedResultsController *) fetchResultsControllerWithPredicate:(NSPredicate *) predicate{
[self.fetchedResultsController.fetchRequest setPredicate:predicate];
[NSFetchedResultsController deleteCacheWithName:@"myCache"];
NSError *error = nil;
if (![self.fetchedResultsController performFetch:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
return _fetchedResultsController;
}
现在当我打印它时,它返回_PFBatchFaultingArray如下: -
"<LibraryItem: 0xdc22150> (entity: LibraryItem; id: 0xdc208b0 <x-coredata://A1159A80-CA8B-4443-B96C-582BF0DC0290/LibraryItem/p332> ; data: <fault>)",
"<LibraryItem: 0xdc224d0> (entity: LibraryItem; id: 0xdc1c590 <x-coredata://A1159A80-CA8B-4443-B96C-582BF0DC0290/LibraryItem/p290> ; data: <fault>)",
"<LibraryItem: 0xdc22510> (entity: LibraryItem; id: 0xdc1c5a0 <x-coredata://A1159A80-CA8B-4443-B96C-582BF0DC0290/LibraryItem/p224> ; data:<fault>)"
问题是“数据:'&lt;'错误'&gt;' ”
此代码有什么问题? 我做错了吗?
感谢您的帮助。
答案 0 :(得分:0)
在浪费了一整天后,我意识到了答案。 是的我们可以修改。
但是一旦您访问数据,您就会找到正确的数据。 因此,如果在打印时显示错误数据,请不要担心。
**When you just trying to print the values it will print a data : fault.
Because CoreData fetch data on Demand, means while you are printing it, it is partial Data.
When you access (you demand) the value, you find the complete data.**