# init(_:) Creates a predicate by converting an existing predicate. ``` convenience init?(_ predicate: Predicate) where Input : NSObject ``` ## Parameters `predicate` The predicate to convert. ## Return Value The converted predicate, or `nil` if conversion fails. ## Discussion Only a subset of predicates that can be expressed by [`Predicate`](/documentation/Foundation/Predicate) are convertible to [`NSPredicate`](/documentation/Foundation/NSPredicate). Predicates that include operations like the following can’t be converted: - Accessing key paths for properties that aren’t exposed to the Objective-C runtime. - Capturing values of types that aren’t supported by `NSPredicate`, like custom Swift structures. - Using some functions or operators, like performing collection operations on a nonstring value. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)