继承CCSprite时不要重写init方法，否则会无限循环

在Learn cocos2D Game Development with iOS 5一书中
第六章提到了A Common and Fatal Mistake
大概说的就是当继承CCSrpite对象的时候不要重写init方法，例如

@interface Ship : CCSprite {}+(id) ship;@implementation Ship+(id) ship{return [[[self alloc] init] autorelease];}-(id) init//这里是错误的{CCLOG(@"Ship init called ... this will repeat infinetely.");// WARNING: this will cause an infinite loop!// Reason: [super initWithFile:...] will call -(id) init which is overridden here ... repeat ad infinitum// Fix: rename this init method, for example initWithShipImage// Tip: never call anything but [super init] in your class' init method. If you call any initWith* method// then you should never do this from the -(id) init method.if ((self = [super initWithFile:@"ship.png"])){[self scheduleUpdate];}return self;}@end

正确的方式应该是这样的

-(id) initWithShipImage//这里的函数名可以随便去，就是不要与init一样{if ((self = [super initWithFile:@"ship.png"])) {[self scheduleUpdate]; }    return self;}

为什么会出现这种问题你自己追踪到CCSprite源码就明白了
1。点击super initWithFile跳转到CCSprite的initWithFile方法中
源码如下

-(id) initWithFile:(NSString*)filename{NSAssert(filename!=nil, @"Invalid filename for sprite");CCTexture2D *texture = [[CCTextureCache sharedTextureCache] addImage: filename];if( texture ) {CGRect rect = CGRectZero;rect.size = texture.contentSize;return [self initWithTexture:texture rect:rect];}[self release];return nil;}

2。点击self initWithTexture跳转到CCSprite的initWithTexture方法中
源码如下

-(id) initWithTexture:(CCTexture2D*)texture rect:(CGRect)rect{NSAssert(texture!=nil, @"Invalid texture for sprite");// IMPORTANT: [self init] and not [super init];if( (self = [self init]) ){[self setTexture:texture];[self setTextureRect:rect];}return self;}

3。注意看上面代码中if( (self = [self init]) )，
你发现OC里边比较习惯的就是用if ((self = [super init]) ),而这里却不是，这就是在继承CCSrpite后如果你重写了init方法程序就会无限循环的原因