2
我在導航層次結構中有2個級別的UITableViews
。第一頁是UITableView
,它使用NSFetchedResultsController
顯示Equipment
的所有實例,這很好。在第二頁上,我想要取回所有Note
實體的特定片段Equipment
,以便我可以在tableView
中顯示它們。如何爲CoreData對多關係編寫NSPredicate
如何編寫NSPredicate
以僅返回相關備註?
- (NSFetchedResultsController *)fetchedResultsController {
if (_fetchedResultsController != nil) {
return _fetchedResultsController;
}
//Init Fetch Request
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
//Entity the NSFetchedResultsController will be managing
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Note"
inManagedObjectContext:self.myContext];
[fetchRequest setEntity:entity];
//Sort Descriptors
NSSortDescriptor *sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:@"noteTime"
ascending:YES];//Primary Sort
NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:@"noteText"
ascending:YES];//Secondary Sort
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor1,
sortDescriptor2,
nil];
//Set Sort Descriptors
[fetchRequest setSortDescriptors:sortDescriptors];
// limit Fetch to notes that belong to myEquipment
//self
// NSPredicate *predicate = [NSPredicate predicateWithFormat:[NSString stringWithFormat:@"item.name like '%@'", self.item.name]];
NSPredicate *predicate = [NSPredicate predicateWithFormat:PREDICATE GOES HERE];
[fetchRequest setPredicate:predicate];
[fetchRequest setFetchBatchSize:10];
NSFetchedResultsController *frc = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
managedObjectContext:self.myContext
sectionNameKeyPath:nil
cacheName:@"Equipment"];
//Set the Delegate Property
frc.delegate = self;
_fetchedResultsController = frc;
//Release Local Memory
[sortDescriptor1 release];
[sortDescriptor2 release];
[sortDescriptors release];
[fetchRequest release];
return _fetchedResultsController;
}
這是否導致了邏輯假讀取請求? 查詢會是(設備== <設備:0x00000000>(實體:設備...) – ebi 2014-06-25 19:24:36