SpriteKit helper function for building loops from TextureAtlases

SubclassOfSKSpriteNode.m

// Assumes consistent file names accross all image sequences (mine are zero-indexed and padded to five digits)
// mainCharacter.atlas
// - idleLoop_00000.png
// - idleLoop_00001.png
// - ...
// - walkLoop_00000.png
// - walkLoop_00001.png
// - ...


- (void)loadAnimations{
  SKAction *animLoopIdle = [self buildLoopFromAtlas:@”mainCharacter” withFileNameFormat:@”idleLoop_%0.5d”];
  SKAction *animLoopWalk = [self buildLoopFromAtlas:@”mainCharacter” withFileNameFormat:@”walkLoop_%0.5d”];
}


-(SKAction *)buildLoopFromAtlas:(NSString *)atlasName withFileNameFormat:(NSString *)fileFormat {
    SKTextureAtlas *loopAtlas = [SKTextureAtlas atlasNamed:atlasName];
    NSMutableArray *atlasArray = [NSMutableArray array];
    
    NSString *fileNameRegex = [[fileFormat substringToIndex:(fileFormat.length - @"%0.5d".length)] stringByAppendingString:@"[0-9]{5}.png"];
    NSPredicate *matchesBaseFilename = [NSPredicate predicateWithFormat:@"SELF MATCHES[c] %@", fileNameRegex];
    NSArray *matchingTextures = [loopAtlas.textureNames filteredArrayUsingPredicate:matchesBaseFilename];
    for(int i=0; i < matchingTextures.count; i++){
        NSString *textureName = [NSString stringWithFormat:fileFormat, i];
        SKTexture *tex = [loopAtlas textureNamed:textureName];
        [atlasArray addObject:tex];
    }
    NSTimeInterval fps24 = (NSTimeInterval)(1.0/24.0);
    SKAction *animation = [SKAction animateWithTextures:atlasArray timePerFrame:fps24 resize:YES restore:YES];
    return [SKAction repeatActionForever:animation];
}