iphone - 使用我的 ccspriteframes 类时出错

Question

我想已经为我的子弹精灵加载了帧，所以我创建了一个类来保存所有精灵帧。当我使用这个类时它崩溃了。我真的可以使用帮助，非常感谢。

。H

@interface loadedFrames : NSObject 
{
    CCSpriteFrame *bullet0;
}
@property (nonatomic, retain) CCSpriteFrame *bullet0;
@end
@interface HelloWorldLayer : CCLayer <GKAchievementViewControllerDelegate, GKLeaderboardViewControllerDelegate>
{
    loadedFrames *frames;
}
@property (nonatomic, retain) loadedFrames *frames;

.m

@implementation loadedFrames : NSObject
@synthesize bullet0;
@end

- (void) loadSprites
{
      [[CCSpriteFrameCache sharedSpriteFrameCache] addSpriteFramesWithFile:
      [NSString stringWithFormat:@"clonespritesheet%d.plist", loadlevel]];

      self.frames.bullet0 = [[CCSpriteFrameCache sharedSpriteFrameCache]
               spriteFrameByName:@"bullet0.png"];
}

- (void) addBullet:(int)bulletType
{
      mainbullet = [bullet spriteWithSpriteFrame:frames.bullet0];
}

崩溃日志

2013-04-01 01:45:42.596 test[15111:907] *** Assertion failure in -[bullet initWithSpriteFrame:], /Users/Fei/Desktop/test/libs/cocos2d/CCSprite.m:212
(lldb)