Creating an RPG with SpriteKit has me creating SKLabelNode's for displaying all game text. I'm suffering performance issues (FPS dropping & the game lagging) every time my multi-line text box begins auto typing inputted text which uses SKLabelNode's. I also see performance hits when "summoning" UI elements, such as character stat panels (with lots of SKLabelNode's for skill levels, skills names, etc.).
Veteran developers say pre-loading data always helps, thus I did the following (which has reduced the performance hit but hasn't eliminated it & the text box still lags):
// Preloaded model label (private property that is initialized in the class init method).
_modelLabel = [[SKLabelNode alloc] initWithFontNamed:_fontName];
_modelLabel.fontColor = _fontColor;
_modelLabel.fontSize = _fontSize;
_modelLabel.text = @"T";
// Constantly created label.
SKLabelNode *rowText = [[SKLabelNode alloc] initWithFontNamed:self.modelLabel.fontName];
rowText.fontColor = self.modelLabel.fontColor;
rowText.fontSize = self.modelLabel.fontSize;
rowText.text = row;
...
[self addChild:rowText];
I would be grateful for getting some more optimizations tricks when using SKLabelNode's. Here are the tips I have collected thus far:
Preloading is only needed when using a font that is not available via iOS.
To get the font to actually load you need to also set the text for the preload to work.
Try to preload SKLabelNode with all chars you need. Maybe, SpriteKit renders only required glyphs into texture.
// Preloaded model label (private property that is initialized in the class init method).
_modelLabel = [[SKLabelNode alloc] initWithFontNamed:_fontName];
_modelLabel.fontColor = _fontColor;
_modelLabel.fontSize = _fontSize;
_modelLabel.text = @"ABCDEFGHIJKLMNOPQRSTUVWXZabcdefghijklmnopqrstuvwxyz0123456789-+=_()";
And then add your model into scene with minimal alpha (but no zero, because if node has 0 alpha, it will not drawn); Try to keep that node in scene
_modelLabel.alpha = CGFLOAT_MIN;
[self addChild:_modelLabel];
If not helps:
zPosition (aka z-index). You should disable ignoresSiblingOrder for having control over zPosition.
Make your all SKLabelNode be drawn at one z level.