# init(predicate:assertingFact:grade:) Creates a data-driven rule with the specified predicate, whose action asserts a fact in the rule system evaluating the rule. ``` convenience init(predicate: NSPredicate, assertingFact fact: any NSObjectProtocol, grade: Float) ``` ## Parameters `fact` An object representing a fact to assert when the rule’s predicate is satisfied. (For details on facts in rule systems, see the [`facts`](/documentation/GameplayKit/GKRuleSystem/facts) property in [`GKRuleSystem`](/documentation/GameplayKit/GKRuleSystem).) `grade` An amount by which to increase the fact’s membership grade if the rule’s predicate is satisfied. ## Return Value A new rule object. ## Discussion Rules created using this method encode their predicate and action when archived with the class. You can use this feature to support saving and loading rules, editing rules in-game, or building tools that separate your gameplay design and game programming tasks. Rules based on objects typically test information in the [`state`](/documentation/GameplayKit/GKRuleSystem/state) dictionary of the rule system evaluating the rule. For example, the following code creates a rule you might use to determine whether an enemy character in a game behaves aggressively. (This example presumes the rule system’s state dictionary contains an object for the key `player`, which in turn exposes a numeric value for the key `health`.) ```swift let healthTest = NSPredicate(format: "$player.health < 25") let rule = GKRule(predicate: healthTest, assertingFact: "player_weak", grade: 0.5) ``` --- 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)