Core Data TableView - Multiple Selection During Edit Mode - objective-c

Question

I have two TableViews using Core Data. I have an ItemTableview with multiple rows of Item listed by the user, and it allows multiple selection during edit mode. During edit mode, it allows user to delete selected items, or delete all of the items at once. I want the items that's been deleted to be added to a TrashTableView.
Here's what I have so far:
- (IBAction)deleteAction:(id)sender
{
NSManagedObjectContext *context = [self managedObjectContext];
NSArray *selectedRows = [self.tableView indexPathsForSelectedRows];
BOOL noItemsAreSelected = selectedRows.count == 0;
BOOL deleteSpecificRows = selectedRows.count > 0;
if (noItemsAreSelected) {
// Delete all objects from the Core Data.
NSFetchRequest *allItems = [[NSFetchRequest alloc] init];
[allItems setEntity:[NSEntityDescription entityForName:#"Item" inManagedObjectContext:context]];
[allItems setIncludesPropertyValues:NO];
NSError *error = nil;
NSArray *items = [context executeFetchRequest:allItems error:&error];
for (NSManagedObject *object in items) {
[context deleteObject:object];
}
// Add to Trash
for (NSManagedObject *trashObject in items) {
Item *selectedItems = trashObject; <-- #warning -Incompatible pointer types initializing "Items" with an expression of type "NSManagedObject"-
Trash *newTrash = [NSEntityDescription insertNewObjectForEntityForName:#"Trash" inManagedObjectContext:context];
newTrash.trashname = selectedItems.itemname;
newTrash.created = [NSDate date];
// Save the context
NSError *saveError = nil;
if (![context save:&saveError]) {
NSLog(#"Save Failed! %# %#", saveError, [saveError localizedDescription]);
}
}
// Delete from the Array
[_item removeAllObjects];
// Tell the tableView that we deleted the objects.
[self.tableView reloadSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationAutomatic];
[self.tableView setEditing:NO animated:YES];
}
else if (deleteSpecificRows) {
NSMutableIndexSet *indicesOfItemsToDelete = [NSMutableIndexSet new];
for (NSIndexPath *selectionIndex in selectedRows)
{
[indicesOfItemsToDelete addIndex:selectionIndex.row];
}
// Delete from the Array
[_item removeObjectsAtIndexes:indicesOfItemsToDelete];
// Tell the tableView that we deleted the objects
[self.tableView deleteRowsAtIndexPaths:selectedRows withRowAnimation:UITableViewRowAnimationAutomatic];
[self.tableView setEditing:NO animated:YES];
}
}
When if (noItemsAreSelected) is called, all of the items are deleted and they all get added to the TrashTableView, but only a first row from the ItemTableView gives the string. So in the TrashTableView, first row has a text but the rest of the rows are just blank cells without any text.
In the debugger, blank cells have NSString trashname = nil; but NSDate created = "2015-01-22 03:41:30 +0000"; has a date.
For else if (deleteSpecificRows) I have no idea how to do it in Core Data....
I've spent quiet a lot of time trying to figure this out, so any help would be greatly appreciated. Thanks!

Answer 1

You are doing things in the wrong order: you currently delete all the items from the context, then iterate through the items, creating the corresponding trash items and saving the context each time. This works OK for the first item. But after the first item, the context has already been saved, so the delete operation (for ALL the items) will have happened, which nils out all their properties. Hence your null values.
I would restructure it as follows:
if (noItemsAreSelected) {
NSFetchRequest *allItems = [[NSFetchRequest alloc] init];
[allItems setEntity:[NSEntityDescription entityForName:#"Item" inManagedObjectContext:context]];
[allItems setIncludesPropertyValues:NO];
NSError *error = nil;
NSArray *items = [context executeFetchRequest:allItems error:&error];
for (Item *trashObject in items) {
// Add to Trash
Trash *newTrash = [NSEntityDescription insertNewObjectForEntityForName:#"Trash" inManagedObjectContext:context];
newTrash.trashname = trashObject.itemname;
newTrash.created = [NSDate date];
// Delete
[context deleteObject:trashObject];
}
// Save the context
NSError *saveError = nil;
if (![context save:&saveError]) {
NSLog(#"Save Failed! %# %#", saveError, [saveError localizedDescription]);
}
Note that changing the cast in the for(Item *trashObject ...) should avoid the compiler warning.
EDIT
For the deleteSpecificRows case, you can use similar code, but using your _item (I assume that is a mutable array which is the datasource for your tableView):
else if (deleteSpecificRows) {
NSMutableIndexSet *indicesOfItemsToDelete = [NSMutableIndexSet new];
for (NSIndexPath *selectionIndex in selectedRows)
{
// First, get the trash object...
Item *trashObject = [_item objectAtIndex:selectionIndex.row];
// Add to Trash
Trash *newTrash = [NSEntityDescription insertNewObjectForEntityForName:#"Trash" inManagedObjectContext:context];
newTrash.trashname = trashObject.itemname;
newTrash.created = [NSDate date];
// and delete the object from the context
[context deleteObject:trashObject];
// and update the list of items to delete
[indicesOfItemsToDelete addIndex:selectionIndex.row];
}
// Delete from the Array
[_item removeObjectsAtIndexes:indicesOfItemsToDelete];
// Tell the tableView that we deleted the objects
[self.tableView deleteRowsAtIndexPaths:selectedRows withRowAnimation:UITableViewRowAnimationAutomatic];
[self.tableView setEditing:NO animated:YES];
}
Note that this is untested, so might need tidying up....
Longer term, you might want to consider a) using a NSFetchedResultsController to act as your datasource for your tableView, and b) rather than creating separate entities for the trash, add flag to the existing entities (inTrash?) and just changing that to true. Your tableView would then have to show only items with inTrash = false.