Question

我有一个类方法，我在其中创建并返回类对象。但我想在同一个类中访问该对象的某些属性。作为一个类方法，我不能在.h文件中声明变量，然后在其他方法中访问它。以下是代码如何在下面的实例方法中访问backsprite或hudlayer对象的值？

    // class 1

+(id)HUDWithBackgroundSprite:(NSString *)spriteName withRect:(CGRect)rect atPoistion:(HUDPosition)pos
{

  HUDlayer *hud = [[HUDlayer alloc] init];

  CCSprite *backSprite = [CCSprite spriteWithFile:spriteName];
  [backSprite setContentSize:CGSizeMake(rect.size.width,rect.size.height)];
  [backSprite setPosition:ccp(rect.origin.x,rect.origin.y)];
  [backSprite setTag:100];
  [hud addChild:backSprite];
  [hud setTag:2];

  return [hud autorelease];
}


// access it here

-(void)AddButtonToHUDWithImage:(NSString *)imageName selector:(SEL)selector withDisabledImage:(NSString *)disbdImageName
{
  HUDlayer *hud = (HUDlayer *)[self getChildByTag:2];

  CCMenuItem *menuItem1 = [CCMenuItemImage itemFromNormalImage:imageName selectedImage:imageName disabledImage:disbdImageName target:self selector:@selector(selector)];

  CCMenu *menu = [CCMenu menuWithItems:menuItem1,nil];

  CCSprite *sprite = (CCSprite *)[hud getChildByTag:100];

  CGPoint pos = sprite.position;
  //pos =[[CCDirector sharedDirector]convertToGL:pos];

  [menu setPosition:ccp(pos.x+160,pos.y-30)];

  [hud addChild:menu];
}

// class 2

+(CCScene *) scene
{
  // 'scene' is an autorelease object.
  CCScene *scene = [CCScene node];

    HUDlayer *hud = [HUDlayer node];
  //  [scene addChild:hud z:1];

  // 'layer' is an autorelease object.
  HelloWorldLayer *layer = [[[HelloWorldLayer alloc]initWithHUD:hud]autorelease];

  // add layer as a child to scene 
  [scene addChild: layer];

  id mainHuds = [HUDlayer HUDWithBackgroundSprite:HUDBackground withRect:CGRectMake(160,450, 300,60) atPoistion:pos_Top];

  SEL callOnClick;
  [mainHuds AddButtonToHUDWithImage:ButtonBackground selector:callOnClick withDisabledImage:disabledBackground];

  [scene addChild: mainHuds];

  // return the scene
  return scene;
}

我无法通过标签访问它，因为这里没有添加+方法中的HUDlayer对象，而是调用该方法的另一个类。

Answer 1

您绝对可以在该类的类访问实例/成员变量的静态方法中使用指向该类实例的指针/引用。这是一个简单的例子......对不起，如果有拼写错误......

// HUDLayer.h

@interface HUDLayer : CCLayer
{
    NSString* aString;
}

@property (nonatomic, retain) NSString* aString;

+(void)modifyInstanceString:(HUDLayer*)hud;

// HUDLayer.m

@implementation HUDLayer

@synthesize aString;

-(id)init
{
    if ((self=[super init]))
    {
        self.aString = @"initial value";
    }
    CCLOG(@"Initial value = %@", self.aString);
    return self;
}

+(void)modifyInstanceString:(HUDLayer*)hud
{
    hud.aString = @"Something else";
    CCLOG(@"Modified aString via static method = %@", hud.aString);
}

@end

// HelloWorldLayer.m（或任何地方）

HUDLayer* hud = [[HUDLayer alloc] init];
[HUDLayer modifyInstanceString:hud];

Answer 2

没有理由不能将对象声明为.h文件中的变量：

HUDlayer * hud;

这正是该类的方法将如何访问它。如果您遇到错误，我只能假设.h文件的布局错误。我通常像这样设置场景和图层：

@interface ExampleLayer : CCLayer
{       
        //vars
}

//methods

@end

@interface ExampleScene : CCScene 
{   
    ExampleLayer *layer;
}

@end

Answer 3

静态方法中只能使用静态变量... 将.h文件中的对象声明为Static HUDlayer * hud; 并使用类名访问它... 仍然M不能理解你为什么要创建这么多静态方法，因为它们很重，并且即使你不需要那个类就预先加载....

从iPhone和＆amp ;;中的类类型（+）方法访问对象cocos2d的？

3 个答案: