Cocos-2d 关于多个CCSprite精灵播放同一个CCAction动画问题

问题描述：

在Cocos-2d场景动画中，常常出现多个Sprite的同一行为动画

假设场景中此时有两个精灵sprite1，sprite2

他们其实点分别在场景左侧，需要完成的动作CCMoteTo到场景最右侧

初始状态如下图：

初始尝试：

- (void)playAction
{
    //1.试图两个精灵播放同一个动画
    CGSize size = [[CCDirector sharedDirector] winSize];

    CCMoveBy *move = [CCMoveBy actionWithDuration:3.0f position:ccp(size.width-[sprite1 textureRect].size.width,0)];
    [sprite1 runAction:move];
    [sprite2 runAction:move];
}

- (void)playAction
{
    //1.试图两个精灵播放同一个动画
    CGSize size = [[CCDirector sharedDirector] winSize];

    CCMoveBy *move = [CCMoveBy actionWithDuration:3.0f position:ccp(size.width-[sprite1 textureRect].size.width,0)];
    [sprite1 runAction:move];
    [sprite2 runAction:move];
}

初始效果展示：

点击Play按钮后效果图：

我们发现尽管在代码中sprite1和sprite2都是runAction:move，但是貌似只有下方的sprite2执行了此动作，而sprite1没有执行。效果不尽人意！

原理解释：

我们跟踪一下

[sprite1runAction:move];

-(CCAction*) runAction:(CCAction*) action
{
    NSAssert( action != nil, @"Argument must be non-nil");

    [actionManager_ addAction:action target:self paused:!isRunning_];
    return action;
}

-(CCAction*) runAction:(CCAction*) action
{
	NSAssert( action != nil, @"Argument must be non-nil");

	[actionManager_ addAction:action target:self paused:!isRunning_];
	return action;
}

重点看一下[addAction:action target:self paused:!isRunning_];

-(void) addAction:(CCAction*)action target:(id)target paused:(BOOL)paused

{

//有效性判断。

NSAssert( action !=nil, @"Argument action must be non-nil");

NSAssert( target !=nil, @"Argument target must be non-nil");

//定义一个哈希表项的指针变量并置空。

tHashElement *element =NULL;

//通过这个指针，找到对应的哈希表项返回给element;

HASH_FIND_INT(targets, &target, element);

//如果找不到。则代表新加入的哈希表项。则申请内存创建此哈希表项，并将其加入哈希表中。

if( ! element ) {

element = calloc(sizeof( *element ), 1 );

element->paused = paused;

element->target = [targetretain];

HASH_ADD_INT(targets,target, element);

// CCLOG(@"cocos2d: ---- buckets: %d/%d - %@", targets->entries, targets->size, element->target);

}

//为哈希表项element申请内存，以存放动画集

[selfactionAllocWithHashElement:element];

//判断action是否在element的动画集中。确保只放入一次。(这也是为什么一个动画不能重复添加的原因!)

NSAssert( !ccArrayContainsObject(element->actions, action), @"runAction: Action already running");

//将action放入element的动画集中。

ccArrayAppendObject(element->actions, action);

//设置是哪个CCNode要进行当前动画 (重点原因在这里！！！)

[action startWithTarget:target];

}

每一个CCAction对象都有且仅有一个target（id 类型）的成员，表示该动画是有哪一个演员来执行的。

所以

[sprite1 runAction:move];
[sprite2 runAction:move];

[sprite1 runAction:move];
[sprite2 runAction:move];

对于同一个move（CCMoveTo对象）来说，第一次[sprite1 runAction:move];我们将move的target成员设置成了sprite1；

而第二次[sprite2 runAction:move];我们又将move的target成员设置成了sprite2；这样第一次注册sprite1的动画move就会失效；

因此效果上只有sprite2在执行move了！

（本段参考“红孩儿Cocos2d-x 2.0 之 Actions “三板斧” 之一”文章：http://www.2cto.com/kf/201211/169345.html 特此做出感谢！）

解决方案：

- (void)playAction
{
    //1.试图两个精灵播放同一个动画
    CGSize size = [[CCDirector sharedDirector] winSize];

    CCMoveBy *move = [CCMoveBy actionWithDuration:3.0f position:ccp(size.width-[sprite1 textureRect].size.width,0)];
    [sprite1 runAction:move];
    //[sprite2 runAction:move];

    //2.改进
    [sprite2 runAction:[move copy]];
}

- (void)playAction
{
    //1.试图两个精灵播放同一个动画
    CGSize size = [[CCDirector sharedDirector] winSize];

    CCMoveBy *move = [CCMoveBy actionWithDuration:3.0f position:ccp(size.width-[sprite1 textureRect].size.width,0)];
    [sprite1 runAction:move];
    //[sprite2 runAction:move];
    
    //2.改进
    [sprite2 runAction:[move copy]];
}

很简单：把move 复制一份，move的副本的target为sprite2，与sprite1无关，这样两个精灵就可以同时执行了。

效果图：

顺便提一句：

1.[CCNode stopAction:action]时

-(void) stopAction: (CCAction*) action
{
    [actionManager_ removeAction:action];
}

-(void) stopAction: (CCAction*) action
{
	[actionManager_ removeAction:action];
}

action会被释放

2.

-(void) removeFromParentAndCleanup:(BOOL)cleanup;

-(void) removeChild: (CCNode*)node cleanup:(BOOL)cleanup;

-(void) removeChildByTag:(NSInteger) tag cleanup:(BOOL)cleanup;

-(void) removeAllChildrenWithCleanup:(BOOL)cleanup;

这是CCNODE的删除对象的方法，后面带了一个cleanup参数，如果你将cleanup的值设为YES,系统在删除对象的时候会对自动对当前对象进行stopAllActions的操作，也会释放action。

3.无论上述哪种方式，一定注意不要内存泄露！

源码分享:

HelloWorldLayer.h

HelloWorldLayer.h

#import

// When you import this file, you import all the cocos2d classes
#import "cocos2d.h"

// HelloWorldLayer
@interface HelloWorldLayer : CCLayer
{
    BOOL isPlay_;
    CCSprite *sprite1;
    CCSprite *sprite2;
}

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

@end

#import 

// When you import this file, you import all the cocos2d classes
#import "cocos2d.h"

// HelloWorldLayer
@interface HelloWorldLayer : CCLayer 
{
    BOOL isPlay_;
    CCSprite *sprite1;
    CCSprite *sprite2;
}

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

@end

HelloWorldLayer.m 这里只贴出有用部分

-(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:@"TwoActionDemo" fontName:@"Marker Felt" fontSize:32];
        CGSize size = [[CCDirector sharedDirector] winSize];
        label.position =  ccp( size.width /2 , 4*size.height/5 );
        [self addChild: label];

         //实例化两个精灵
        sprite1 = [CCSprite spriteWithFile:@"Icon.png"];
        sprite2 = [CCSprite spriteWithFile:@"Icon.png"];
        sprite1.position = ccp([sprite1 textureRect].size.width/2 , size.height/2);
        sprite2.position = ccp([sprite1 textureRect].size.width/2 , size.height/4);
        [self addChild:sprite1];
        [self addChild:sprite2];

         //菜单按钮
        CCMenuItem *play = [CCMenuItemFont itemWithString:@"Play"];
        CCMenuItem *stop = [CCMenuItemFont itemWithString:@"Stop"];
        CCMenuItem *menuBtn = [CCMenuItemToggle itemWithTarget:self selector:@selector(btnPressed) items:play,stop, nil];
        CCMenu *menu = [CCMenu menuWithItems:menuBtn, nil];
        menu.position = ccp(9*size.width /10 , size.height/10);
        [self addChild:menu];

        isPlay_ = NO;

    }
    return self;
}

-(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:@"TwoActionDemo" fontName:@"Marker Felt" fontSize:32];
		CGSize size = [[CCDirector sharedDirector] winSize];
		label.position =  ccp( size.width /2 , 4*size.height/5 );
		[self addChild: label];
        
        //实例化两个精灵
        sprite1 = [CCSprite spriteWithFile:@"Icon.png"];
        sprite2 = [CCSprite spriteWithFile:@"Icon.png"];
        sprite1.position = ccp([sprite1 textureRect].size.width/2 , size.height/2);
        sprite2.position = ccp([sprite1 textureRect].size.width/2 , size.height/4);
        [self addChild:sprite1];
        [self addChild:sprite2];
		
        //菜单按钮
        CCMenuItem *play = [CCMenuItemFont itemWithString:@"Play"];
        CCMenuItem *stop = [CCMenuItemFont itemWithString:@"Stop"];
        CCMenuItem *menuBtn = [CCMenuItemToggle itemWithTarget:self selector:@selector(btnPressed) items:play,stop, nil];
		CCMenu *menu = [CCMenu menuWithItems:menuBtn, nil];
        menu.position = ccp(9*size.width /10 , size.height/10);
        [self addChild:menu];
		
        isPlay_ = NO;

	}
	return self;
}

- (void)btnPressed
{
    isPlay_ = !isPlay_;
    YES == isPlay_ ? [self playAction]:[self stopToOrignPostion];
}

- (void)playAction
{
    //1.试图两个精灵播放同一个动画
    CGSize size = [[CCDirector sharedDirector] winSize];

    CCMoveBy *move = [CCMoveBy actionWithDuration:3.0f position:ccp(size.width-[sprite1 textureRect].size.width,0)];
    [sprite1 runAction:move];
    //[sprite2 runAction:move];

    //2.改进
    [sprite2 runAction:[move copy]];
}

- (void)stopToOrignPostion
{
    [self stopAllActions];

    CGSize size = [[CCDirector sharedDirector] winSize];

    CCPlace *place1 = [CCPlace actionWithPosition:ccp([sprite1 textureRect].size.width/2 , size.height/2)];
    CCPlace *place2 = [CCPlace actionWithPosition:ccp([sprite1 textureRect].size.width/2 , size.height/4)];
    [sprite1 runAction:place1];
    [sprite2 runAction:place2];
}

- (void)btnPressed
{
    isPlay_ = !isPlay_;
    YES == isPlay_ ? [self playAction]:[self stopToOrignPostion];
}

- (void)playAction
{
    //1.试图两个精灵播放同一个动画
    CGSize size = [[CCDirector sharedDirector] winSize];

    CCMoveBy *move = [CCMoveBy actionWithDuration:3.0f position:ccp(size.width-[sprite1 textureRect].size.width,0)];
    [sprite1 runAction:move];
    //[sprite2 runAction:move];
    
    //2.改进
    [sprite2 runAction:[move copy]];
}

- (void)stopToOrignPostion
{
    [self stopAllActions];
    
    CGSize size = [[CCDirector sharedDirector] winSize];
    
    CCPlace *place1 = [CCPlace actionWithPosition:ccp([sprite1 textureRect].size.width/2 , size.height/2)];
    CCPlace *place2 = [CCPlace actionWithPosition:ccp([sprite1 textureRect].size.width/2 , size.height/4)];
    [sprite1 runAction:place1];
    [sprite2 runAction:place2];
}

// on "dealloc" you need to release all your retained objects
- (void) dealloc
{
    [sprite1 release];
    "white-space: pre;">    [sprite2 release];
    [super dealloc];
}