cocos2d学习（一）helloWorld

一.继承关系

CCNode

CCLayer CCScene CCSprite

CCMenu CCTransitionScene CCLabel

CCLayer

CCLayerColor CCLayerMultiplex CCMenu

CCLayerGrident

一般Layer中都有一个生成包含此layer的场景（scene）的类方法：

#import "cocos2d.h"

// HelloWorldLayer
@interface HelloWorldLayer : CCLayer <GKAchievementViewControllerDelegate, GKLeaderboardViewControllerDelegate>
{
}

// returns a CCScene that contains the HelloWorldLayer as the only child
+(CCScene *) scene;

@end

.m一般有一个init方法

+(CCScene *) scene
{
    // 'scene' is an autorelease object.
    CCScene *scene = [CCScene node];//生成场景对象
    
    // 'layer' is an autorelease object.
    HelloWorldLayer *layer = [HelloWorldLayer node];//生成层对象
    
    // add layer as a child to scene
    [scene addChild: layer];//将层加入场景中
    
    // return the scene
    return scene;//返回场景对象
}

// on "init" you need to initialize your instance
-(id) init
{
    // always call "super" init
    // Apple recommends to re-assign "self" with the "super's" return value
    if( (self=[super init]) ) {
        
        // create and initialize a Label
        CCLabelTTF *label = [CCLabelTTF labelWithString:@"Hello" fontName:@"Marker Felt" fontSize:10];
        //加入语句
        label.tag = 13;
        self.isTouchEnabled = YES;
        // ask director for the window size
        CGSize size = [[CCDirector sharedDirector] winSize];
    
        // position the label on the center of the screen
        label.position =  ccp( size.width /2 , size.height/2 );
        
        // add the label as a child to this Layer
        [self addChild: label];
        
        CCLabelTTF *labelTest = [CCLabelTTF labelWithString:@"test" fontName:@"Marker Felt" fontSize:64];
        labelTest.tag = 100;
        labelTest.position = ccp(size.width /2,size.height/4);
      
        labelTest.visible = NO;
        [self addChild:labelTest];
        //
        // Leaderboards and Achievements
        //
        
        // Default font size will be 28 points.
        [CCMenuItemFont setFontSize:28];
        
        // Achievement Menu Item using blocks
        CCMenuItem *itemAchievement = [CCMenuItemFont itemWithString:@"Achievements" block:^(id sender) {
            
            
            GKAchievementViewController *achivementViewController = [[GKAchievementViewController alloc] init];
            achivementViewController.achievementDelegate = self;
            
            AppController *app = (AppController*) [[UIApplication sharedApplication] delegate];
            
            [[app navController] presentModalViewController:achivementViewController animated:YES];
            
            [achivementViewController release];
        }
                                       ];

        // Leaderboard Menu Item using blocks
        CCMenuItem *itemLeaderboard = [CCMenuItemFont itemWithString:@"Leaderboard" block:^(id sender) {
               
            
            GKLeaderboardViewController *leaderboardViewController = [[GKLeaderboardViewController alloc] init];
            leaderboardViewController.leaderboardDelegate = self;
            
            AppController *app = (AppController*) [[UIApplication sharedApplication] delegate];
            
            [[app navController] presentModalViewController:leaderboardViewController animated:YES];
            
            [leaderboardViewController release];
        }
                                       ];
        
        CCMenu *menu = [CCMenu menuWithItems:itemAchievement, itemLeaderboard, nil];
        
        [menu alignItemsHorizontallyWithPadding:20];
        [menu setPosition:ccp( size.width/2, size.height/2 - 50)];
        
        // Add the menu to the layer
        [self addChild:menu];
        //[self scheduleUpdate];
        //[self schedule:@selector(update:) interval:1.0f];
    }
    return self;
}

1.[self schedule:@selector(update:) interval:1.0f];是cocos2d中常用的定时更新的方法，如果用

[self scheduleUpdate];则它会默认隔一段时间执行名为update:的方法
2.设置响应触摸事件：self.isTouchEnabled = YES;
然后可以实现-(void) ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event以及move，end方法
3.触摸事件分发

-(void) registerWithTouchDispatcher
{
    [[[CCDirector sharedDirector] touchDispatcher] addTargetedDelegate:self
                                                              priority:INT_MIN+1
                                                       swallowsTouches:YES];
}
-(BOOL)ccTouchBegan:(UITouch *)touch withEvent:(UIEvent *)event
{
    return YES;//return YES则吞没触摸事件
}

层(CCLayer)是cocos2d中传递触摸信息的载体，系统会将接收到的触摸事件传递给层的对象，默认情况下激活场景包含的所有层对象都会收到该信息，但也有一个特殊的层是例外，那就是——菜单(CCMenu)。

CCMenu其实也继承自CCLayer，因此他们都可以加收到触摸信息，但不同的是，CCMenu会“吞掉”自己接受到的触摸事件，使该信息无法传递给它后面的层，这也很好理解，假如有若干个层叠在一起的按钮，那么当我们点击的时候，响应的肯定是最上边那个，如果所有按钮都响应，那用户就要头大了……菜单就是根据这一特性而从层中被单独抽象出来的，它使得UI中同时只会有一个控件被选中。

那么层又是如何接收到玩家的触摸事件的呢？它和IOS系统又是怎样交互的？答案都在CCTouchDispatcher这个类中。

CCTouchDispatcher是个单例，程序刚启动时，导演类会将其设为EAGLView触摸代理，当玩家有触摸操作时，系统会自动调用它的对应方法。之前在介绍层的时候提到过，CCLayer通过registerWithTouchDispatcher方法将自己注册到CCTouchDispatcher单例中，CCTouchDispatcher检测到触摸信息后，会在注册队列中遍历这些对象，调用它们的响应方法，使它们可以响应触摸事件。

+ (CCTouchDispatcher*)sharedDispatcher

获取单例对象，单例类的惯用方法。

(void) registerWithTouchDispatcher

和CCLayer中的作用一样，只是CCMenu调用的是addTargetedDelegate方法，可以吞掉触摸事件，优先级为-128。

4.触摸点转化为cocos2d中对应的坐标

UITouch *touch = [touches anyObject];

CGPoint touchLocation = [touch locationInView: [touch view]];

CGPoint p = [[CCDirector sharedDirector] convertToGL:touchLocation];