我有一个奇怪的错误：如果我取消注释 my NSPredicate，结果UITableView是空的。
我的数据模型如下：类别 <-->> Feed <-->> Post
我正在取Posts。Post.feed是一个Post。有财产。FeedFeedrss NString
这是代码：
- (NSFetchedResultsController *)fetchedResultsController {
// Set up the fetched results controller if needed.
if (_fetchedResultsController == nil) {
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Post"
inManagedObjectContext:_globalMOC];
[fetchRequest setEntity:entity];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
NSPredicate *predicate =[NSPredicate predicateWithFormat:@"feed.rss == %@", _detailItem.rss];
[fetchRequest setPredicate:predicate];
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController =
[[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
managedObjectContext:_globalMOC
sectionNameKeyPath:nil
cacheName:nil];
self.fetchedResultsController = aFetchedResultsController;
self.fetchedResultsController.delegate = self;
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. If it is not possible to recover from the error, display an alert
// panel that instructs the user to quit the application by pressing the Home button.
//
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
return _fetchedResultsController;
}
如果我取消注释，我只会看到结果NSPredicate。我尝试使用LIKE, ==, =, 用双引号和单引号%@...
最好是直接比较Feed对象...
任何人都可以帮助我吗？