---
title: "enter(_:)"
framework: gameplaykit
role: symbol
role_heading: Instance Method
path: "gameplaykit/gkstatemachine/enter(_:)"
---

# enter(_:)

Attempts to transition the state machine from its current state to a state of the specified class.

## Declaration

```swift
func enter(_ stateClass: AnyClass) -> Bool
```

## Parameters

- `stateClass`: The class of state into which to attempt a transition.

## Return Value

Return Value true if the transition was successful; otherwise false.

## Discussion

Discussion You build a state machine by creating a unique GKState subclass for each distinct state possible for the machine. The isValidNextState(_:) method of each state object determines which other states a state machine is allowed to transition into from that state. Calling this method first tests whether a transition from the current state to the specified state is valid; if not, this method returns false. If a transition is allowed, the state machine sends the willExit(to:) message to its current state object. Then, the new state object replaces the value of the currentState property. Finally, the state machine sends the  didEnter(from:) message to the new current state object, and this method returns true. A newly created state machine’s currentState property is nil—to choose and enter an initial state, use the enter(_:) method. In this case, the enter(_:) call always succeeds.

## See Also

### Working with States

- [currentState](gameplaykit/gkstatemachine/currentstate.md)
- [canEnterState(_:)](gameplaykit/gkstatemachine/canenterstate(_:).md)
- [update(deltaTime:)](gameplaykit/gkstatemachine/update(deltatime:).md)