A simple rubber band pop animation I created.

UIView+Pop.h

#import <UIKit/UIKit.h>

@interface UIView (Pop)

- (void)popWithMagnitude:(CGFloat)magnitude numPops:(int)numPops duration:(CGFloat)duration;

@end

UIView+Pop.m

#import "UIView+Pop.h"

@implementation UIView (Pop)

- (void)popWithMagnitude:(CGFloat)magnitude numPops:(int)numPops duration:(CGFloat)duration {
    numPops -=1;
    
    void (^growAnimation)() = ^{
        self.transform = CGAffineTransformScale(CGAffineTransformIdentity, 1.0f + magnitude, 1.0f + magnitude);
    };
    
    void (^shrinkAnimation)() = ^{
        self.transform = CGAffineTransformScale(CGAffineTransformIdentity, 1.0f - magnitude * 0.75f, 1.0f - magnitude * 0.75f);
    };
    
    void (^shrinkCompletion)(BOOL) = ^(BOOL finished) {
        if (numPops == 0)
        {
            [UIView animateWithDuration:duration * 1.5f animations:^{
                self.transform = CGAffineTransformIdentity;
            } completion:nil];
            
            return;
        }
        
        [self popWithMagnitude:magnitude * 0.5f numPops:numPops duration:duration * 1.5f];
    };
    
    void (^growCompletion)(BOOL) = ^(BOOL finished) {
        [UIView animateWithDuration:duration * 1.25f animations:shrinkAnimation completion:shrinkCompletion];
    };
    
    [UIView animateWithDuration:duration animations:growAnimation completion:growCompletion];
}

@end