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Editorial Team
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Asked: 2026-05-16T08:10:24+00:00

Using Core Data. Let’s say we have models for Team and Player. Assume: -Each

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Using Core Data. Let’s say we have models for Team and Player.

Assume:
-Each player is a member of a single team
-Relevant relationships have been made in a xcdatamodel file.

I have a TeamListViewController (listing all teams), when I select a team I want to see a list of just those players related to that selected team on the PlayerListViewController.

I then want to be able to select an individual player and see PlayerViewController and review their personal information, edit details etc.

I know how to use the fetchResultsController to pull in a list of all players.

  1. How do I best go about pulling in the data needed to show just the players for the selected team?

  2. Also, If I just pull the data into an Array so I can display it, how do I also ensure that the array remains in sync with core data when other changes are made to a record?

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1 Answer

  1. Editorial Team

    What you need to fetch objects matching certain criteria is a NSPredicate.

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"team=Tigers"];
[fetchRequest setPredicate:predicate];

    Now the fetch request returns results where the team attribute = “Tigers”. Without the predicate it would return all objects.

    Predicates can get complex – you can have multiple conditions and special operators are defined like “ANY” or “LIKE”. See the Predicate Programming Guide

    On your second question – do you anticipate accessing the Core Data store with multiple threads? Start reading… you need a managed object context for each thread. If not you basically don’t need to worry. Changes to the underlying store are “faulted in” just as if you follow a relationship to an object you have not explicitly fetched.

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