GameplayKit的GKStateMachine用法与实例

GKStateMachine

玩家进入GameScene场景中 -> 通过GKStateMachine进入到指定的游戏状态GKState

在GameScene场景中 -> 根据不同的逻辑调用GKStateMachine -> 在各个不同的游戏状态GKState之间进行切换

源码如下：

一、GameScene.swft

import SpriteKit
import GameplayKit

class GameScene: SKScene,SKPhysicsContactDelegate {
    
    //MARK: - StateMachine 场景中各个舞台State
    lazy var stateMachine:GKStateMachine = GKStateMachine(states: [
        WaitingState(scene: self), PlayState(scene: self), GameOverState(scene: self)]) override func didMove(to view: SKView) { stateMachine.enter(MenuState.self) // 进入MenuState } func restartGame(){ let newScene = GameScene(fileNamed: "GameScene")! newScene.size = CGSize(width: SCENE_WIDTH, height: SCENE_HEIGHT) newScene.anchorPoint = CGPoint(x: 0, y: 0) newScene.scaleMode = .aspectFill let transition = SKTransition.crossFade(withDuration: TimeInterval(0.5)) view?.presentScene(newScene, transition:transition) //reload GameScene 直接进入游戏状态; newScene.stateMachine.enter(PlayState.self) } override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) { guard let touch = touches.first else { return } // 当 physicsWorld.body(at: touchLocation)为nil时 // 采用atPoint 取得场景中的的精灵 let touchLocation = touch.location(in: self) ///获得点击的位置 let nodeAtPoint = self.atPoint(touchLocation) //返回SKNode /// 判断目前的GameScene场景舞台是哪个state switch stateMachine.currentState { case is WaitingState: /// 判断是否是点击了PlayButton if nodeAtPoint.name == "playButton" { stateMachine.enter(PlayState.self) } if nodeAtPoint.name == "learnTemp" { print("weird") UIApplication.shared.open(URL(string: "http://www.iFIERO.com")!, options: convertToUIApplicationOpenExternalURLOptionsKeyDictionary([:]), completionHandler: { (error) in print("jump to http://www.iFiero.com") }) } case is PlayState: //挑战：判断是否是点击了暂停按钮 PauseButton // if nodeAtPoint.name == "pauseButton" { // stateMachine.enter(PauseState.self) // } break; case is GameOverState: if nodeAtPoint.name == "tapToPlay" { restartGame() } default: break; } } //MARK: - 时时更新 override func update(_ currentTime: TimeInterval) { /// 获取时间差 if lastUpdateTimeInterval == 0 { lastUpdateTimeInterval = currentTime } dt = currentTime - lastUpdateTimeInterval lastUpdateTimeInterval = currentTime stateMachine.update(deltaTime: dt) // 调用所有State内的update方法 } }

二、MenuState.swft

//
//  MenuState.swift
//  Copyright © 2018 iFiero. All rights reserved.
//

import SpriteKit import GameplayKit class MenuState:GKState { // 必须引入场景(如:GameScene) unowned let scene:GameScene // 执行didEnter前，可在init()初始化代码 init(scene:SKScene){ self.scene = scene as! GameScene super.init() print("Menu State") } // 进入当前状态时触发 override func didEnter(from previousState: GKState?) { } // 离开当前状态时触发 override func willExit(to nextState: GKState) { } /* 返回一个布尔值 * 该值指示当前处于该状态的状态机是否允许转换到指定状态 * 通俗点讲就是：如果stateMachine(状态机)的状态是PlayState,那么就从MenuState状态转到PlayState状态 */ override func isValidNextState(_ stateClass: AnyClass) -> Bool { return stateClass is PlayState.Type } // Execute Update Per Frame,游戏运行过程中的每一帧都会执行 // 但须在GameScene update内调用stateMachine.update() override func update(deltaTime seconds: TimeInterval) { } }

三、PlayingState.swft

import SpriteKit
import GameplayKit

class PlayState:GKState { unowned let scene:GameScene init(scene:SKScene){ self.scene = scene as! GameScene super.init() print("Play State") } override func didEnter(from previousState: GKState?) { } // 挑战:创建游戏暂停GKState状态 PauseState.swift // return (stateClass == PauseState.self) || (stateClass == GameOverState.self) override func isValidNextState(_ stateClass: AnyClass) -> Bool { return stateClass is GameOverState.Type } // Excute Update Per Frame override func update(deltaTime seconds: TimeInterval) { // update 用于判断球的速度是否过快，如果太快了则设置linearDamping的阻力 } }

四、GameOverState.swft

import SpriteKit
import GameplayKit

class GameOverState:GKState { unowned let scene:GameScene init(scene:SKScene){ self.scene = scene as! GameScene super.init() } override func didEnter(from previousState: GKState?) { print("GameOver State 游戏结束") } override func isValidNextState(_ stateClass: AnyClass) -> Bool { return stateClass is PlayState.Type // return (stateClass == PlayState.self) || (stateClass == MenuState.self) } }

更多游戏教学：http://www.iFIERO.com -- 为游戏开发深感自豪

源码传送门:https://github.com/apiapia/BreakOutGameVansVTutorial

GameplayKit的GKStateMachine用法与实例

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