正确使用Cocos2D中的绘制方法

Question

我想创建一个简单的图层来显示一些信息，如分数。

我成功地做到这样，但是我真的不知道这是正确的：

#import "InformationLayer.h" 
#import "GameScene.h" 

@implementation InformationLayer 

-(void) draw 
{ 
    // Complete clear of the screen 
    [self removeAllChildrenWithCleanup:true]; 

    // Draw my score 
    [self DrawScore]; 
} 

- (void)DrawScore 
{ 
    // create and initialize a label 
    NSString* l_sScore = [NSString stringWithFormat:@"Score : %d", [[GameScene sharedGameScene] iScore]]; 

    CCLabelTTF* label = [CCLabelTTF labelWithString:l_sScore fontName:@"Marker Felt" fontSize:32]; 

    // get the window (screen) size from CCDirector 
    CGSize size = [[CCDirector sharedDirector] winSize]; 

    // position the label at the center of the screen 
    label.position = CGPointMake(size.width - ([label texture].contentSize.width/2), size.height*2.0/3.0); 

    // add the label as a child to this Layer 
    [self addChild:label]; 
} 
@end 

我处理我的场景和层很像，所有的时间，我真的不舒适清除我的所有层然后再绘制一切。在我看来，这是一个彻头彻尾的矫枉过正！尽管如此，它的工作......

由于我在我的学习曲线的底部，我想快速做对......我可以在这里做更好的事情吗？

Answer 1

这是完全错误的。只添加一次节点。仅当您想使用OpenGL绘制某些东西（或使用ccDrawLine等cocos2d函数）时才使用draw方法。您可以添加您的内容（标签，精灵等），例如，在一些init方法中。

要更改标签的文字，请使用setString:方法。

Answer 2

所以以下莫里恩的建议是：

-(id) init 
{ 
    if((self=[super init])) 
    { 
     [self InitLabels]; 

     // Scheduling the refresh method. 
     [self scheduleUpdate]; 
    } 
    return self; 
} 

// Update replaces draw !! 
-(void)update:(ccTime)delta 
{ 
    [self UpdateLabels]; 
} 

- (void)InitLabels 
{ 
    // get the window (screen) size from CCDirector 
    CGSize l_ScreenSize = [[CCDirector sharedDirector] winSize]; 
    float l_iScreenHeightPosition = l_ScreenSize.height*2.0/3.0; 

    NSString* l_sScore = [NSString stringWithFormat:@"Score : %d", [[GameScene sharedGameScene] iScore]]; 
    NSString* l_sLevel = [NSString stringWithFormat:@"Level : %d", [[GameScene sharedGameScene] iLevel]]; 

    l_lblScore = [CCLabelTTF labelWithString:l_sScore 
              fontName:@"Marker Felt" fontSize:32]; 

    l_lblScore.position = CGPointMake(l_ScreenSize.width - ([l_lblScore texture].contentSize.width/2), l_iScreenHeightPosition); 

    // add the label as a child to this Layer 
    [self addChild:l_lblScore]; 

    l_lblLevel = [CCLabelTTF labelWithString:l_sLevel 
               fontName:@"Marker Felt" fontSize:32]; 

    l_lblLevel.position = CGPointMake(l_ScreenSize.width - ([l_lblLevel texture].contentSize.width/2), l_iScreenHeightPosition - ([l_lblScore texture].contentSize.height)); 

    // add the label as a child to this Layer 
    [self addChild:l_lblLevel]; 
} 

- (void)UpdateLabels 
{ 
    NSString* l_sScore = [NSString stringWithFormat:@"Score : %d", [[GameScene sharedGameScene] iScore]]; 
    NSString* l_sLevel = [NSString stringWithFormat:@"Level : %d", [[GameScene sharedGameScene] iLevel]]; 

    [l_lblScore setString:l_sScore]; 
    [l_lblLevel setString:l_sLevel]; 
} 

看来，最好是我现在:)