dealing with textureAtlas and spritekit all about preloading texture atlas and remove them when you not need them anymore

spritekit is a cool 2d framework designed by apple with support fast 2d graphics rendering one of the killer feature of sprite kit is texture atlas a

what is a texture atlas

https://developer.apple.com/library/ios/recipes/xcode_help-texture_atlas/_index.html

working with texture atlas in sprite kit is very easy.



example

#import "GameScene.h"

@implementation GameScene

{

    UIImage *defaultImg;

    int MCrow;

    int MCcoloum;

    float imgWidth;

    float imgHeight;

    NSArray *atlasArray;

    NSMutableArray *fetchedAtlas;

    NSDictionary *dict1;

    NSDictionary *dict2;

    NSDictionary *dict3;

    NSDictionary *dict4;

    NSDictionary *dict5;

    NSDictionary *dict6;

    NSDictionary *dict7;

    SKSpriteNode *node;

}

-(void)didMoveToView:(SKView *)view {

    /* Setup your scene here */

    MCrow=3;

    MCcoloum=3;

 /*

loading all texture atlas in memory after ten second

*/   

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{

        [self drawAllTextures];

    });

}

-(void)drawAllTextures

{

    

/*

all my texture atlas 

*/

atlasArray=@[@"yellowseahorse",@"stingray",@"tiger",@"shark",@"mathlab",@"zipline",@"hurdies"];

//and empty array thats holds a group of textureAtlas

    

fetchedAtlas=[[NSMutableArray alloc] init];

    

    

    for(int i=0;i<[atlasArray count];i++)

    {

        //add texture atlas to a NSMutableArray 

        [fetchedAtlas addObject:[self getAtlas:atlasArray[i]]];

    }

//preload texture atlas 

    [SKTextureAtlas preloadTextureAtlases:fetchedAtlas withCompletionHandler:^{

        

        //fetch all texture from textureAtlas and add them their respective dictionary 

        dict1=[self fetchTexturesFromAtlas:fetchedAtlas[0]];

        dict2=[self fetchTexturesFromAtlas:fetchedAtlas[1]];

        dict3=[self fetchTexturesFromAtlas:fetchedAtlas[2]];

        dict4=[self fetchTexturesFromAtlas:fetchedAtlas[3]];

        dict5=[self fetchTexturesFromAtlas:fetchedAtlas[4]];

        dict6=[self fetchTexturesFromAtlas:fetchedAtlas[5]];

        dict7=[self fetchTexturesFromAtlas:fetchedAtlas[6]];

        

    }];

}

-(NSMutableDictionary*)fetchTexturesFromAtlas:(SKTextureAtlas*)atlas

{

    NSMutableDictionary *SKTextureDictionary=[[NSMutableDictionary alloc] init];

    for(int i=0;i<[atlas.textureNames count];i++)

    {

        SKTexture *texture=[self createTextureFromAtlas:atlas texture:atlas.textureNames[i]];

        NSArray *fullname=[atlas.textureNames[i] componentsSeparatedByString:@"."];

        [SKTextureDictionary setObject:texture forKey:fullname[0]];

    }

    return SKTextureDictionary;

}

-(SKTexture*)createTextureFromAtlas:(SKTextureAtlas *)atlas texture:(NSString*)textureName

{

    SKTexture *spriteTexture=[atlas textureNamed:textureName];

    return spriteTexture;

}

//fetch texture atlas from memory

-(SKTextureAtlas*)getAtlas:(NSString*)name

{

    return [SKTextureAtlas atlasNamed:name];

}

//

-(void)drawObjects

{

    for (NSString* key in dict1) {

        node=[SKSpriteNode spriteNodeWithTexture:[dict1 objectForKey:key]];

        node.position=CGPointMake(400, 400);

        [self addChild:node];

       

    }

    for (NSString* key in dict2) {

        node=[SKSpriteNode spriteNodeWithTexture:[dict2 objectForKey:key]];

        node.position=CGPointMake(300, 300);

        [self addChild:node];

        

    }

    for (NSString* key in dict3) {

        node=[SKSpriteNode spriteNodeWithTexture:[dict3 objectForKey:key]];

        node.position=CGPointMake(100, 100);

        [self addChild:node];

        

    }

}

-(void)removeAllAtlas

{

//remove all reference of texture atlas and all textures 

    dict1=nil;

    dict2=nil;

    dict3=nil;

    dict4=nil;

    dict5=nil;

    dict6=nil;

    dict7=nil;

    [fetchedAtlas removeAllObjects];

    [self removeAllChildren];

     fetchedAtlas=nil;

   

    

}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    /* Called when a touch begins */

     [self drawObjects];

  }

-(void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event

{

    

    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{

        [self removeAllAtlas];

    });

}

-(void)update:(CFTimeInterval)currentTime {

    /* Called before each frame is rendered */

    

}

@end