CODEWITHSUNDEEP
iosobjective-cnsfetchedresultscontroller
Nuno Dias
Nuno Dias

Reputation: 3948

How to get fetchedResultsController to feed my TableView, based on an object that was retrieved from another FRC in a previous view controller?

Here's my structure:

I have an Entity called Element. And Element contains multiple Time Stamps. Time Stamp is an Entity with a relationship to element.

Element
   Time Stamp 1
   Time Stamp 2
   Time Stamp 3,
   ...,
   ...

My View Controllers and Table View are:

View Controller A
   TableView A // <- displays elements

View Controller B
   TableView B // <- should display all timestamps from a given element

What I'm trying to do:

I can get my "Element" in View Controller A, and pass it along to View Controller B, like this:

Element *anElement = [_fetchedResultsController objectAtIndexPath:indexPath];

ViewControllerB *vc = (ViewControllerB *)[[self storyboard]instantiateViewControllerWithIdentifier:@"ViewControllerB"];
vc.element = anElement;

Now, on my View Controller B I have a fetchedResultsController that feeds my Table View B. I need this fetchedResultsController show all the Time Stamps from the passed Element object.

How can I do this?

I know I could fix this, by adding a unique date property to Element, so that I could have a predicate in my View Controller B that matched that unique date. However, if posible, I rather not do that. I find it hard to believe that I need to have my Core Data Entity to have a dependency on what I need to do in my View Controllers.

Thank you!

Upvotes: 0

Views: 55

Answers (2)

Craig Siemens
Craig Siemens

Reputation: 13296

You should be able to user the following predicate with your fetchedResultsController to get the TimeStamp objects.

[NSPredicate predicateWithFormat:@"element == %@", self.element];

Upvotes: 1

random
random

Reputation: 8608

If Time stamp is an NSSet you could just pass that along to ViewController B and do away with the fetchedResultsController in B.

Or instead of assigning the entity as done in above, pass along the NSManagedObjectID to ViewController B and do a fetch based on that. This would be a better way of doing if you want to use a fetch controller in B.

Upvotes: 0

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