NSPredicate with Swift and Core Data

Question

i have a Core Data Object and i have 2 Fieds (one String(GUID) and one Int which i want to use as Filter)

So in SQL it would be \"SELECT * FROM Answers WHERE qIndex = 1

Answer 1

Instead of worrying about %@ conversions and then composing AND predicates, you can use the PredicatePal framework:

let compound = *(Key("qIndex") == qIndex && Key("formUUID") == formUUID)

Assuming that qIndex and formUUID are the correct type, Swift will automatically deduce the correct types for the Key objects.

Answer 2

This is not the exact response to your question, but a problem people might now encouter with your code now:

In the latest version of XCode, you must now unwrap the predicate, like this:

var compound = NSCompoundPredicate.andPredicateWithSubpredicates([predicate1!, predicate2!])

because NSPredicate initializer now return NSPredicate? type.

Answer 3

If formUUID is an NSString or a Swift String then you have to use the %@ placeholder:

let resultPredicate2 = NSPredicate(format: "formUUID = %@", formUUID)