This isn’t really specific to NSPredicate… Whenever you have %@ in a format string, the corresponding value must be a pointer to an object, and BOOL doesn’t qualify. So instead of passing YES, pass [NSNumber numberWithBool: YES]. In newer versions of Xcode and the SDKs than when I originally wrote the answer, you can use … Read more
Based on Apple Document Here, we can use the following two methods to compare Boolean: NSPredicate *newPredicate = [NSPredicate predicateWithFormat:@”anAttribute == %@”,[NSNumber numberWithBool:aBool]]; NSPredicate *testForTrue = [NSPredicate predicateWithFormat:@”anAttribute == YES”]; However, the above predicate cannot get out the ones with empty anAttribute. To deal with an empty attribute, you need the following method according to … Read more
To test for an empty relationship you should compare the count of the to-many key to zero. [NSPredicate predicateWithFormat:@”excludedOccurrences.@count == 0″]; As for your subpredicates, be aware that you can only have one of either the ALL or ANY modifiers in your final predicate, although you can use that modifier multiple times throughout the predicate. … Read more
NSNumber is an object type. Unlike NSString, the actual value of NSNumber is not substitued when used with %@ format. You have to get the actual value using the predefined methods, like intValue which returns the integer value. And use the format substituer as %d as we are going to substitute an integer value. The … Read more
Your first predicate NSPredicate *predicate = [NSPredicate predicateWithFormat:@”listingID != %@”, sessionID]; should work to find all records where the attribute listingID is not equal to sessionID (provided that listingID and sessionID have the same type). If both are strings and you want to find all records where listingID does not contain the string sessionID as … Read more
As Dave DeLong said, you can use: NSPredicate *predicate = [NSPredicate predicateWithFormat:@”UPC ==[c] %@ OR ItemID ==[c] %@”, aUPCCode,aUPCCode]; Edit: Use ==[c] instead of ==[cd] or you get accents too (abcd == àbcd).
-[NSManagedObject objectID] is the unique ID for an object instance in Core Data. It can be serialized via -[NSManagedObjectID URIRepresentation]. You can retrieve the objectID from a persistent store coordinator with -[NSPersistentStoreCoordinator managedObjectIDForURIRepresentation:] and then get the object from a managed object context with -[NSManagedObjectContext objectWithID:]. BUT You should keep in mind that Core Data … Read more
NSPredicate *predicate = [NSPredicate predicateWithFormat:@”type == %@”, @”standard”]; NSArray *filteredArray = [myArray filteredArrayUsingPredicate:predicate]; id firstFoundObject = nil; firstFoundObject = filteredArray.count > 0 ? filteredArray.firstObject : nil; NB: The notion of the first found object in an NSSet makes no sense since the order of the objects in a set is undefined.
Addition to @Stuart’s answer, you can use NSCompoundPredicate for your OR & AND operations like this. Obj-C – OR // OR Condition // NSPredicate *predicate1 = [NSPredicate predicateWithFormat:@”X == 1″]; NSPredicate *predicate2 = [NSPredicate predicateWithFormat:@”X == 2″]; NSPredicate *predicate = [NSCompoundPredicate orPredicateWithSubpredicates:@[predicate1, predicate2]]; Obj-C – AND NSPredicate *predicate1 = [NSPredicate predicateWithFormat:@”X == 1″]; NSPredicate *predicate2 … Read more
Take a look at keypaths. They are super powerful and I use them instead of NSPredicate classes most of the time. Here is how you would use them in your example… NSArray *uniqueStates; uniqueStates = [customObjects valueForKeyPath:@”@distinctUnionOfObjects.state”]; Note the use of valueForKeyPath instead of valueForKey. Here is a more detailed/contrived example… NSDictionary *arnold = [NSDictionary … Read more