Question

In my data model, I have:

Activity(name, sponsor, Location*) // one activity may have many Locations
Location(name, street, suburb, state, postcode)

And I need a way to get activities with specified location name, for example, user wants to know all activities in “ICT Building”, so how do I construct the predicate for the query?

Something like:

"Location.name == ICT Building" ?

Thanks!

Answer 1

Use this where managedObjectContext is your context:

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
    entityForName:@"Activity" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
NSString *locationName = @"ICT Building";
NSPredicate *pred = [NSPredicate predicateWithFormat:@"Location.name CONTAINS %@", locationName];
[fetchRequest setPredicate:pred];
NSError *error = nil;
NSArray *objects = [managedObjectContext executeFetchRequest:fetchRequest error:&error];

This will return an array with managed objects where the name is ICT Building.