How to update the score without generating countless nodes? - ios

Question

I have this game when a sprite touches the sides, you get a point. I figured out the code to increment the score each time the sprite touches the side. I get the correct output through the NSLog message.
But, When I try the same code by changing the code from NSLog to SKLabelNode, I get a more than a thousand nodes (which I think will affect the performance and slow the game).Also, when the score gets incremented, it overlaps the old score rather than just increasing the score. I have added the code in the update with frame.
Heres the code:
- (void)printScore {
NSString *text = [NSString stringWithFormat:#"%ld",(long)userScore];
SKLabelNode *score = [SKLabelNode labelNodeWithText:text];
score.fontName = #"chalkduster";
score.fontSize = 45;
score.fontColor = [SKColor whiteColor];
score.position = CGPointMake(CGRectGetMidX(self.frame) + 175 ,CGRectGetMidY(self.frame) + 350);
[self addChild:score];
}
-(void)update:(CFTimeInterval)currentTime {
[self printScore];
}
How do I fix this so that the score gets updated without so many sprites being added?
Sorry if this is a really dumb question, I am noob.

Answer 1

Add just a single property:
#property (nonatomic, strong) SKLabelNode *scoreLabel;
And create it just one time in viewDidLoad o an init method:
_scoreLabel = [SKLabelNode initWithFontNamed:#"chalkduster"];
_scoreLabel.fontSize = 45;
_scoreLabel.fontColor = [SKColor whiteColor];
_scoreLabel.position = CGPointMake(CGRectGetMidX(self.frame) + 175 ,CGRectGetMidY(self.frame) + 350);
[self addChild:_scoreLabel];
Then call the printScore method only when the sprite touches de sides, not on each frame like you are doing in the update method:
- (void)printScore
{
NSString *text = [NSString stringWithFormat:#"%ld",(long)userScore];
self.scoreLabel.text = text;
}
I hope this helps.

Answer 2

The reason you get so many nodes is that you are constantly adding new labels to the scene. Notice that in your printScore method you are create new SKLabelNode instances and then adding that to the scene.
In order to correct that, you will want to maintain a reference to a single SKLabelNode and then update the text of that.
Also, you may want to move the call to printScore to only be called when the actual scoring event happens, as opposed to update which is called for every frame. I'm of course assuming you do not have a scoring event happen every frame.

Answer 3

Your printScore method creates a new SKLabelNode every time it is called and you are calling it 60 times a second via your update method. You should set a BOOL to notify you of the need to call your printScoreMethod only when there is a need to do so (as in the score has changed).

Answer 4

create a global boolean and only add the label the first time:
BOOL firsttime = YES;
- (void)printScore {
NSString *text = [NSString stringWithFormat:#"%ld",(long)userScore];
SKLabelNode *score = [SKLabelNode labelNodeWithText:text];
if( firsttime )
{
score.fontName = #"chalkduster";
score.fontSize = 45;
score.fontColor = [SKColor whiteColor];
score.position = CGPointMake(CGRectGetMidX(self.frame) + 175, CGRectGetMidY(self.frame) + 350);
[self addChild:score];
firsttime = NO;
}
}
-(void)update:(CFTimeInterval)currentTime {
[self printScore];
}

Answer 5

There are a few ways to approach this. I prefer an approach which hides as much of the underlying implementation. Ideally, I would actually create a class which represents the score HUD. From a "rest of the app code" perspective, the other game code's contract with the HUD is through a score property which reflects the score.
Some will argue it is one label and it seems like a hassle. But if you change how it is implemented (for example, say it becomes a score with a fill bar or perhaps you have special effects which accompany a change in score), you will find it makes it super easy to deal with. Or what if you suddenly have a 2 player game and both players track score? You can easily add a new score by adding a new instance of your the score class.
Here is a simple example of what I mean.
ScoreHUD.h
#interface ScoreHUD : NSObject
#property (nonatomic, assign) NSInteger score;
- (instancetype)initWithScene:(SKScene *)scene x:(CGFloat)x y:(CGFloat)y;
#end
ScoreHUD.m
#interface ScoreHUD()
#property (nonatomic, strong) SKLabelNode *scoreLabel;
#end
#implementation ScoreHUD
- (instancetype)initWithScene:(SKScene *)scene x:(CGFloat)x y:(CGFloat)y
{
self = [super init];
if (self) {
_scoreLabel = [SKLabelNode initWithFontNamed:#"chalkduster"];
_scoreLabel.fontSize = 45;
_scoreLabel.fontColor = [SKColor whiteColor];
_scoreLabel.position = CGPointMake(x, y);
[scene addChild:_scoreLabel];
// Setting initial label value to the default value of the score
_scoreLabel.text = [#(_score) stringValue];
}
return self;
}
- (void)setScore:(NSInteger)score
{
if (_score != score) {
_score = score;
self.scoreLabel.text = [#(score) stringValue];
}
}
#end
Note that I haven't tested the code or checked to see if it would compile.
So to use this, you would create an instance of this in your scene like:
// Property in the scene
#property (nonatomic, strong) ScoreHUD *score;
// Initialize where you need to
self.score = [[ScoreHUD alloc] initWithScene:self x:CGRectGetMidX(self.frame) + 175 y:CGRectGetMidY(self.frame) + 350];
You could do this in your scene's initWithSize.
When the score changes, you simply do something like:
self.score.score += 1;
You can always wrap that in another method if it looks nasty to you.
There is a drawback to this method. Say your score get's updated a lot during a frame. This means your text would be set multiple times per frame. Depending on the type of game you have, this may or may not be a concern. There are ways to still have this basic setup and work around it. But for the vast majority of games, it will not be an issue.