- (void)presentationTransitionWillBegin {
    self.bgView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.blurView = [[UIVisualEffectView alloc]initWithEffect:[UIBlurEffect effectWithStyle:UIBlurEffectStyleDark]];
    self.blurView.frame = self.containerView.bounds;
    [self.bgView insertSubview:self.blurView atIndex:0];
    self.contentView = self.containerView;
    [self.contentView addSubview:self.presentedViewController.view];
    [self.contentView addSubview:self.bgView];
    [self.contentView addSubview:self.presentedView];
    
    self.bgView.alpha = 0;
    self.transitionCoodinator = self.presentingViewController.transitionCoordinator;

    [self.transitionCoodinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context) {
        self.bgView.alpha = 0.7;
        self.presentingViewController.view.transform = CGAffineTransformTranslate(self.presentingViewController.view.transform, 0, 30);
    } completion:nil];
}

- (BOOL)shouldRemovePresentersView {
    return NO;
}

- (void)presentationTransitionDidEnd:(BOOL)completed {
    if (!completed) {
        [self.bgView removeFromSuperview];
    }
}

- (void)dismissalTransitionWillBegin {
    self.transitionCoodinator = self.presentingViewController.transitionCoordinator;
    [self.transitionCoodinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> context) {
        self.bgView.alpha = 0;
        self.presentingViewController.view.transform = CGAffineTransformIdentity;
    } completion:nil];
}

- (void)dismissalTransitionDidEnd:(BOOL)completed {
    if (completed) {
        [self.bgView removeFromSuperview];
        [[self.presentingViewController childViewControllers][1] viewDidLoad];
        [[[UIApplication sharedApplication] keyWindow] addSubview: self.presentingViewController.view];
    }
}

- (void)wireToViewController:(UIViewController *)viewController {
    self.presentingVC = viewController;
    UIPanGestureRecognizer *gesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handleGesture:)];
    [viewController.view addGestureRecognizer:gesture];
}

-(CGFloat)completionSpeed {
    return 1 - self.percentComplete;
}

- (void)handleGesture:(UIPanGestureRecognizer *)gestureRecognizer {
    CGPoint translation = [gestureRecognizer translationInView:gestureRecognizer.view.superview];
    switch (gestureRecognizer.state) {
        case UIGestureRecognizerStateBegan:
            self.interacting = YES;
            [self.presentingVC dismissViewControllerAnimated:YES completion:nil];
            break;
        case UIGestureRecognizerStateChanged: {
            CGFloat fraction = translation.y / 400.0;
            fraction = fminf(fmaxf(fraction, 0.0), 1.0);
            self.shouldComplete = (fraction > 0.5);
            [self updateInteractiveTransition:fraction];
            break;
        }
        case UIGestureRecognizerStateEnded:
        case UIGestureRecognizerStateCancelled: {
            self.interacting = NO;
            if (!self.shouldComplete || gestureRecognizer.state == UIGestureRecognizerStateCancelled) {
                [self cancelInteractiveTransition];
            } else {
                [self finishInteractiveTransition];
            }
            break;
        }
        default:
            break;
    }
}

- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext {
    return 0.8f;
}

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext {
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

    CGRect screenBounds = [[UIScreen mainScreen] bounds];
    CGRect finalFrame = [transitionContext finalFrameForViewController:toVC];
    toVC.view.frame = CGRectOffset(finalFrame, 0, screenBounds.size.height);
    
    UIView *containerView = [transitionContext containerView];
    [containerView addSubview:toVC.view];
    
    NSTimeInterval duration = [self transitionDuration:transitionContext];
    [UIView animateWithDuration:duration
                          delay:0.0
         usingSpringWithDamping:0.7
          initialSpringVelocity:0.0
                        options:UIViewAnimationOptionCurveLinear
                     animations:^{
                         toVC.view.frame = finalFrame;
                     } completion:^(BOOL finished) {
                         [transitionContext completeTransition:YES];
                     }];
}

- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext {
    return 0.4f;
}

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext {
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey] ;
    if ([toVC isKindOfClass:[UINavigationController class]]) {
        UINavigationController *vc = (UINavigationController *)toVC;
        vc.navigationBar.frame = CGRectMake(0, 0, vc.navigationBar.width, 64);
    }
    CGRect screenBounds = [[UIScreen mainScreen] bounds];
    CGRect initFrame = [transitionContext initialFrameForViewController:fromVC];
    CGRect finalFrame = CGRectOffset(initFrame, 0, screenBounds.size.height);
    
    UIView *containerView = [transitionContext containerView];
    [containerView addSubview:toVC.view];
    [containerView sendSubviewToBack:toVC.view];
    
    NSTimeInterval duration = [self transitionDuration:transitionContext];
    [UIView animateWithDuration:duration animations:^{
        fromVC.view.frame = finalFrame;
    } completion:^(BOOL finished) {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
    }];
}