State Machine Pattern in C#

public interface IState
{
    void Enter();  void Tick();  void Exit();
}

public class StateMachine
{
    private IState _current;
    public void SetState(IState next)
    {
        _current?.Exit();
        _current = next;
        _current?.Enter();
    }
    public void Tick() => _current?.Tick();
}

// Usage
public class IdleState : IState
{
    public void Enter()  => Debug.Log("Entering Idle");
    public void Tick()   { /* check transitions */ }
    public void Exit()   => Debug.Log("Leaving Idle");
}