efficient way to create animations - objective-c

Question

i was wondering if there is a more efficient way to create animations using pngs ..?
SKSpriteNode *sprite = [SKSpriteNode spriteNodeWithImageNamed:#"a1"];
SKTexture *a1 = [SKTexture textureWithImageNamed:#"a1"];
SKTexture *a2 = [SKTexture textureWithImageNamed:#"a2"];
SKTexture *a3 = [SKTexture textureWithImageNamed:#"a3"];
SKTexture *a4 = [SKTexture textureWithImageNamed:#"a4"];
SKTexture *a5 = [SKTexture textureWithImageNamed:#"a5"];
NSArray *animationFramesFarmer = #[a1, a2, a3, a4, a5];
SKAction *action = [SKAction animateWithTextures:animationFramesFarmer timePerFrame:0.2];
SKAction *endlessAction = [SKAction repeatActionForever:action];
[sprite runAction:endlessAction];

Answer 1

For some reason it seems most people posting here love the in app programmatic generation of their data.
Rather than efficient, I would look at flexible. For that, one of the best ways is to create your own "format" to represent the animation.
For example, here is a simple JSON that represents the what you are doing:
{
"frames" :
[
"a1",
"a2",
"a3",
"a4",
"a5"
],
"timePerFrame": 0.2
"iterations": -1
}
I've used -1 to represent "forever".
Your animation format loader then can be as "efficient" as you want. Atlases are the better way to go, but that really just means adjusting your format to accommodate that.
What are the benefits? Well, you can have an artist generate your the data for you. So their deliverable contains the image(s) and the data file. Even better if you have a tool chain to do it for you.
You also aren't coding specific "generator" sections just to create each animation type.
This is a simplistic case I've outlined above. I build games and I have an art toolset which then export the data out the formats I need and can tell you from experience, in the long run your life is way easier.
One last note. Seeking efficiency is fine, but make sure you need it. Too often I find people pre-optimize or needlessly optimize. Get it working, run it, see where you bottlenecks are (i.e profile). If you create that character only once, then it can be the most efficient code out there, but it won't matter for your overall frame rate/performance of the app.

Answer 2

You could create the frames in a loop like this
SKSpriteNode *sprite = [SKSpriteNode spriteNodeWithImageNamed:#"a1"];
NSMutableArray *animationFramesFarmer = [[NSMutableArray alloc] init];
for (int i = 1; i <= 5; i++)
{
NSString *name = [NSString stringWithFormat:#"a%i", i];
SKTexture *a = [SKTexture textureWithImageNamed:name];
[animationFramesFarmer addObject:a];
}
SKAction *action = [SKAction animateWithTextures:animationFramesFarmer timePerFrame:0.2];
SKAction *endlessAction = [SKAction repeatActionForever:action];
[sprite runAction:endlessAction];