Layer Provide the Basis for Drawing and Animations
Layer manages the information of their geometry, content and visual attributes of their surfaces.
Unlike views, layer doesn't define their own appearance.
Layer merely manages the state information surrounding bitmap

Create Animation with UIImageView
If you want to create a simple animation with ten lines of code, then UIImageView will be good choice.

1. Load the images[png file] to an array.
2. Create UIImageView object and set a few properties.
3. Start the animation. Done!

            NSArray *imageNames = @[@"dance_0.png",
            NSMutableArray *images = [[NSMutableArray alloc] init];
            for (int i = 0; i < imageNames.count; i++) {
                [images addObject:[UIImage imageNamed:[imageNames objectAtIndex:i]]];

            // Normal Animation
            UIImageView *animationImageView = [[UIImageView alloc] 
            initWithFrame:CGRectMake(60, 60, 400, 400)];

            animationImageView.animationImages = images;
            animationImageView.animationDuration = 0.5;

            [self.view addSubview:animationImageView];
            [animationImageView startAnimating];