我试图对实体文件夹执行获取请求,并且我想要一个名为xyz
的文件夹作为排序后的最后一个对象。NSSortDescriptor不被调用
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:@"Folder" inManagedObjectContext:appDelegate.managedObjectContext];
[fetchRequest setEntity:entity];
NSSortDescriptor *lastDescriptor =
[[[NSSortDescriptor alloc] initWithKey:@"folderName" ascending:YES comparator:^NSComparisonResult(NSString* name1, NSString* name2) {
NSLog(@"descriptor");
if ([name1 isEqualToString:@"xyz"]) {
return NSOrderedAscending;
}
if ([name2 isEqualToString:@"xyz"]) {
return NSOrderedDescending;
}
return [name1 compare:name2];
}] autorelease];
[fetchRequest setSortDescriptors:[NSArray arrayWithObject:lastDescriptor]];
[fetchRequest setFetchBatchSize:5];
NSFetchedResultsController *theFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:appDelegate.managedObjectContext sectionNameKeyPath:nil cacheName:nil];
self.fetchedResultsController = theFetchedResultsController;
self.fetchedResultsController.delegate=self;
[fetchRequest release];
[theFetchedResultsController release];
NSError *error;
if (![[self fetchedResultsController] performFetch:&error]) {
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
exit(-1); // Fail
}
但是没有任何一个NSLog语句被调用。他们应该吗?并且xyz文件夹不会最后出现,但所有内容都按字母顺序排序。难道我做错了什么?
编辑:发布完整的代码
我也许是一个愚蠢的问题,但你是否实际执行取回?这只是建立这种排序。 – danh 2012-04-11 15:40:15
嗯,我确实得到了结果,他们只是没有正确排序。我最终得到按字母顺序排列的结果,尽管这是我打电话时唯一的排序描述符。 – Snowman 2012-04-11 15:42:33
NSLog语句是否应该显示出来? – Snowman 2012-04-11 15:45:44