Question

我有一个包含节标题和节行的tableview。我试图用不同的键路径对标题和行进行排序。我希望标题按日期排序，并且要按不同的键路径排序。

-(NSFetchRequest *)entryListFetchRequest{
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"NapEntry"];

[fetchRequest setSortDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"date" ascending:NO],
                                   [NSSortDescriptor sortDescriptorWithKey:@"timePicker" ascending:NO selector:@selector(compare:)]]];

return fetchRequest;
}

标题正确排序，但行不排序。行是按时间排序的NSDate。现在他们只是按输入顺序排序，而不是按时间排序。

-(NSFetchedResultsController *)fetchedResultsController{
if(_fetchedResultsController != nil){
    return _fetchedResultsController;
}

CoreDataStack *coreDataStack =[CoreDataStack defaultStack];
NSFetchRequest *fetchRequest = [self entryListFetchRequest];

_fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:coreDataStack.managedObjectContext sectionNameKeyPath:@"sectionName" cacheName:nil];
_fetchedResultsController.delegate = self;

return _fetchedResultsController;

}

这是我的cellForRow方法：

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

static NSString *CellIdentifier = @"Cell";
NapCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

NapEntry *entry = [self.fetchedResultsController objectAtIndexPath:indexPath];
[cell configureCellForEntry:entry];

cell.backgroundColor = [UIColor whiteColor];


return cell;
}

为什么第二个sortDescriptorWithKey“timePicker”没有排序表行的任何想法？

ADDED实体的NSManagedObject子类*

#import "NapEntry.h"


@implementation NapEntry

@dynamic date;
@dynamic timePicker;
@dynamic timer;


//assigns section headers
- (NSString *)sectionName {
NSDate *date = [NSDate dateWithTimeIntervalSince1970:self.date];

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"EEEE  MMM d, yyyy"];

return [dateFormatter stringFromDate:date];
}
@end

Answer 1

NSFetchedResultsController对象sectionNameKeyPath属性值必须对应NSFetchRequest第一个排序描述符，即指定节标题的方式。其余的排序描述符用于对每个部分中的行进行排序。

所以基本上你应该可以试试这个：

NSSortDescriptor *sd1 = [NSSortDescriptor sortDescriptorWithKey:@"sectionName" ascending:NO];
NSSortDescriptor *sd2 = [NSSortDescriptor sortDescriptorWithKey:@"date" ascending:NO];
NSSortDescriptor *sd3 = [NSSortDescriptor sortDescriptorWithKey:@"datePicker" ascending:NO];  // note sure compare: is needed
[fetchRequest setSortDescriptors:@[sd1, sd2, sd3];

这假设你的模型对象有一个sectionName属性，你要按部分排序。

SortDescriptors，表行不排序

1 个答案: