我无法理解这里发生了什么......
-(void)viewWillAppear:(BOOL)animated
{
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [ NSEntityDescription entityForName:kTransaction inManagedObjectContext:self.context];
[fetchRequest setEntity:entity];
NSSortDescriptor *sort = [[NSSortDescriptor alloc]
initWithKey:kDate ascending:NO];
[fetchRequest setSortDescriptors:[NSArray arrayWithObject:sort]];
NSPredicate *pred;
if (self.willShowDebts) {
pred = [NSPredicate predicateWithFormat:@"isDebt = YES"];
}else {
pred = [NSPredicate predicateWithFormat:@"isLoan = YES"];
}
[fetchRequest setPredicate:pred];
[self setFetchController:nil];
self.fetchController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.context sectionNameKeyPath:nil cacheName:nil];
NSError *error;
if (![self.fetchController performFetch:&error]) {
// Update to handle the error appropriately.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
exit(-1); // Fail
}
[self.tableView reloadData];
NSLog(@"fetch objects %i",[[self.fetchController fetchedObjects] count]);
[super viewWillAppear:animated];
}
我在我的应用程序中这样做了大约 4 次......在这里它不太工作......它第一次显示所有实体,但如果我返回(它在导航控制器中)然后再次转到此视图一切都消失了......什么给了
2012-09-06 13:54:15.994 app[1126:fe03] fetch objects 3
2012-09-06 13:54:19.254 app[1126:fe03] fetch objects 0
2012-09-06 13:54:22.145 app[1126:fe03] fetch objects 0
2012-09-06 13:54:24.328 app[1126:fe03] fetch objects 0
这是日志输出...有什么想法吗?