Core Animation

Core Animation is a graphics rendering and animation infrastructure use to animate the views and other visual elements. Core Animation is not a replacement for app’s views. Instead, it is a technology that integrates with views to provide better performance and support for animating their content. All you have to do is configure a few animation parameters (such as the start and end points) and tell Core Animation to start. Core Animation does the rest, handing most of the actual drawing work off to the onboard graphics hardware to accelerate the rendering. This automatic graphics acceleration results in high frame rates and smooth animations without burdening the CPU and slowing down your app.

Below code add "Pulse Effect" animation.

//Create a CALayer
CALayer *animatelayer = [CALayer layer];
//Setting Frame for CALayer
animatelayer.frame = CGRectMake(0,0, 160, 160);
//Setting Color for CALayer
animatelayer.backgroundColor = [UIColor redColor].CGColor;
//Setting Position for CALayer
animatelayer.position = (CGPoint){CGRectGetMidX(self.view.bounds), CGRectGetMidY(self.view.bounds)};
//Setting Corner radius for CALayer to look like a Circle
animatelayer.cornerRadius = 80;

//Create a Basic Animation
CABasicAnimation *theAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
theAnimation.duration=2.0;
theAnimation.repeatCount=HUGE_VALF;
theAnimation.autoreverses=YES;theAnimation.fromValue=[NSNumber numberWithFloat:0.7];
theAnimation.toValue=[NSNumber numberWithFloat:0.0];

//Add animation to CALayer
[animatelayer addAnimation:theAnimation forKey:@"animateOpacity"];

//Add CALayer to View
[self.view.layer insertSublayer:animatelayer atIndex:0];

For details Click here