# isValidNextState(_:) Returns a Boolean value indicating whether a state machine currently in this state is allowed to transition into the specified state. ``` func isValidNextState(_ stateClass: AnyClass) -> Bool ``` ## Parameters `stateClass` A custom [`GKState`](/documentation/GameplayKit/GKState) class used in the same state machine as this state. ## Return Value if a transition into the specified state should be allowed; otherwise, . ## Discussion When you call the [`canEnterState(_:)`](/documentation/GameplayKit/GKStateMachine/canEnterState(_:)) or [`enter(_:)`](/documentation/GameplayKit/GKStateMachine/enter(_:)) method of a [`GKStateMachine`](/documentation/GameplayKit/GKStateMachine) object [`currentState`](/documentation/GameplayKit/GKStateMachine/currentState) property is this state, the state machine calls this method to determine whether a transition to the proposed next state is allowed. Override this method in each custom state class you implement to choose which other states should be valid transitions from this state. > Note: > GameplayKit may call this method at any time. Your implementation of this method should describe the static relationships between state classes that determine the set of edges in a state machine’s state graph. Do not use this method to conditionally control state transitions—instead, perform such conditional logic before calling a state machine’s ``doc://com.apple.gameplaykit/documentation/GameplayKit/GKStateMachine/enter(_:)`` method. By restricting the set of valid state transitions, you can use a state machine to enforce invariant conditions in your code. For example, if one state class can be entered only after a state machine has passed through a series of other states, code in that state class can safely assume that any actions performed by those other states have already occurred. --- 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)