Method replace current root view controller to new view controller with animation and different orientations

UIViewController+ReplaceRoot.h

//
//  UIViewController+ReplaceRoot.h
//
//  Created by Victor Surikov on 08/03/16.
//  Copyright © 2016 Victor Surikov. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface UIViewController (ReplaceRoot)

+ (void)replaceCurrentRootViewControllerTo:(UIViewController *)newViewController;

@end

UIViewController+ReplaceRoot.m

//
//  UIViewController+ReplaceRoot.m
//
//  Created by Victor Surikov on 08/03/16.
//  Copyright © 2016 Victor Surikov. All rights reserved.
//

#import "UIViewController+ReplaceRoot.h"


BOOL OrientationMaskSupportsOrientation(UIInterfaceOrientationMask mask, UIInterfaceOrientation orientation) {
    return (mask & (1 << orientation)) != 0;
}


@implementation UIViewController (ReplaceRoot)

+ (void)replaceCurrentRootViewControllerTo:(UIViewController *)newViewController {
    id<UIApplicationDelegate> appDelegate = [UIApplication sharedApplication].delegate;
    UIViewController *currentViewController = appDelegate.window.rootViewController;

    CGRect currentRect = currentViewController.view.frame;

    UIInterfaceOrientation interfaceOrientation = [UIApplication sharedApplication].statusBarOrientation;
    BOOL orientationSupported = OrientationMaskSupportsOrientation(
            newViewController.supportedInterfaceOrientations,
            interfaceOrientation);

    CGRect newRect = orientationSupported
            ? CGRectMake(0, 0, currentRect.size.width, currentRect.size.height)
            : CGRectMake(0, 0, currentRect.size.height, currentRect.size.width);

    newViewController.view.frame = newRect;
    [newViewController.view layoutIfNeeded];
    UIImage *newViewControllerAsImage = [self imageWithView:newViewController.view];

    if (!orientationSupported) {
        UIImageOrientation newImageOrientation;

        switch (interfaceOrientation) {
            case UIInterfaceOrientationPortrait:
                if (OrientationMaskSupportsOrientation(newViewController.supportedInterfaceOrientations, UIInterfaceOrientationLandscapeLeft)) {
                    newImageOrientation = UIImageOrientationRight;
                } else if (OrientationMaskSupportsOrientation(newViewController.supportedInterfaceOrientations, UIInterfaceOrientationLandscapeRight)) {
                    newImageOrientation = UIImageOrientationLeft;
                } else {
                    newImageOrientation = UIImageOrientationDown;
                }
                break;
            case UIInterfaceOrientationPortraitUpsideDown:
                if (OrientationMaskSupportsOrientation(newViewController.supportedInterfaceOrientations, UIInterfaceOrientationLandscapeLeft)) {
                    newImageOrientation = UIImageOrientationLeft;
                } else if (OrientationMaskSupportsOrientation(newViewController.supportedInterfaceOrientations, UIInterfaceOrientationLandscapeRight)) {
                    newImageOrientation = UIImageOrientationRight;
                } else {
                    newImageOrientation = UIImageOrientationDown;
                }
                break;
            case UIInterfaceOrientationLandscapeRight:
                if (OrientationMaskSupportsOrientation(newViewController.supportedInterfaceOrientations, UIInterfaceOrientationPortrait)) {
                    newImageOrientation = UIImageOrientationLeft;
                } else if (OrientationMaskSupportsOrientation(newViewController.supportedInterfaceOrientations, UIInterfaceOrientationPortraitUpsideDown)) {
                    newImageOrientation = UIImageOrientationRight;
                } else {
                    newImageOrientation = UIImageOrientationDown;
                }
                break;
            case UIInterfaceOrientationLandscapeLeft:
                if (OrientationMaskSupportsOrientation(newViewController.supportedInterfaceOrientations, UIInterfaceOrientationPortrait)) {
                    newImageOrientation = UIImageOrientationRight;
                } else if (OrientationMaskSupportsOrientation(newViewController.supportedInterfaceOrientations, UIInterfaceOrientationPortraitUpsideDown)) {
                    newImageOrientation = UIImageOrientationLeft;
                } else {
                    newImageOrientation = UIImageOrientationDown;
                }
                break;
            default:
                newImageOrientation = UIImageOrientationUp;
        }
        newViewControllerAsImage = [[UIImage alloc] initWithCGImage:newViewControllerAsImage.CGImage
                                                              scale:1.0
                                                        orientation:newImageOrientation];
    }

    UIImageView *imageView = [[UIImageView alloc] initWithImage:newViewControllerAsImage];
    imageView.backgroundColor = [UIColor whiteColor];
    [appDelegate.window addSubview:imageView];
    imageView.frame = CGRectMake(
            currentRect.origin.x,
            currentRect.origin.y + currentRect.size.height,
            currentRect.size.width,
            currentRect.size.height
    );

    [UIView animateWithDuration:1.0
                     animations:^{
                         imageView.frame = currentRect;
                     }
                     completion:^(BOOL finished) {
                         if (finished) {
                             appDelegate.window.rootViewController = newViewController;
                             [appDelegate.window makeKeyAndVisible];
                         }
                     }];
}

#pragma mark Private helper methods

+ (UIImage *)imageWithView:(UIView *)view {
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, 0.0);
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];
    
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return img;
}

@end