Grid ViewController Transitions

TJLGridTransitions.m

-(NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext {
    return .7;
}
-(void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {
    UIViewController *toController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIViewController *fromController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    
    CGRect finalFrame = [transitionContext finalFrameForViewController:toController];
    
    UIView *containerView = [transitionContext containerView];
    toController.view.frame = finalFrame;
    
    [containerView addSubview:toController.view];
    
    for(NSInteger i = 0; i < 9; i++) {
        for(NSInteger j = 0; j < 5; j++) {
            UIView *square = [fromController.view resizableSnapshotViewFromRect:CGRectMake(j * 64, i * 64, 64, 64) afterScreenUpdates:NO withCapInsets:UIEdgeInsetsZero];
            square.frame = CGRectMake(j * 64, i * 64, 64, 64);
            [containerView addSubview:square];
            [UIView animateWithDuration:[self transitionDuration:transitionContext] delay:(j + i) * .1 usingSpringWithDamping:.6 initialSpringVelocity:0 options:UIViewAnimationOptionCurveLinear animations:^{
                square.center = containerView.center;
                square.layer.transform = CATransform3DMakeScale(.1, .1, 1.0);
            } completion:^(BOOL finished) {
                [square removeFromSuperview];
                if(i == 8 && j == 4) 
                 [transitionContext completeTransition:YES];
            }];
        }
    }