A bouncy movein effect for image grids that I experimented with. Don't want to lose it. Demo: https://vimeo.com/61078361

gistfile1.m

- (void)pushInViewsWithBounce {
    
    self.collectionView.hidden = NO;
    for (NSInteger i=0; i<100; i++){
        
        UIView * viewToAnimate = [self.view viewWithTag:i];
        if ([viewToAnimate isKindOfClass:[AFCollectionViewCell class]]){
            viewToAnimate.hidden = YES;
            CALayer * layerToMove = viewToAnimate.layer;
            
            CGPoint endPoint = CGPointMake(layerToMove.position.x, layerToMove.position.y);
            CGPoint currentPoint = CGPointMake(layerToMove.position.x, layerToMove.position.y+1000.0f);
            
            CAKeyframeAnimation* moveAnimation;
            moveAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
            moveAnimation.duration = .8f;
            moveAnimation.removedOnCompletion = NO;
            moveAnimation.fillMode = kCAFillModeBackwards;
            moveAnimation.calculationMode = kCAAnimationLinear;
            moveAnimation.values = @[[NSValue valueWithCGPoint:currentPoint],
                                     [NSValue valueWithCGPoint:CGPointMake(endPoint.x, endPoint.y-10)],
                                     [NSValue valueWithCGPoint:CGPointMake(endPoint.x, endPoint.y+10)],
                                     [NSValue valueWithCGPoint:CGPointMake(endPoint.x, endPoint.y-5)],
                                     [NSValue valueWithCGPoint:CGPointMake(endPoint.x, endPoint.y+5)],
                                     [NSValue valueWithCGPoint:CGPointMake(endPoint.x, endPoint.y-1)],
                                     [NSValue valueWithCGPoint:CGPointMake(endPoint.x, endPoint.y+1)],
                                     [NSValue valueWithCGPoint:endPoint]];
            [moveAnimation setTimingFunctions:@[
             [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn],
             [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut],
             [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn],
             [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut],
             [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
             [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]
             ]];
            
            double delayInSeconds = 0.15f * i;
            dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
            dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
                viewToAnimate.hidden = NO;
                [viewToAnimate.layer addAnimation:moveAnimation forKey:@"moveIn"];
            });
        }
    }
}