UIView Container pattern

ViewsContainerController.h

//
// Created by Andrey Streltsov on 09/03/16.
//

@import UIKit;

enum eViewControllerIndentifiers {
    eIdentifier1, // the one with rendered whole course map
    eIdentifier2, // the one with MapKit map
    eIdentifier3 // the one with rendered hole map
};

@interface ViewsContainerController : UIViewController

- (void) switchTo:(enum eViewControllerIndentifiers)viewControllerIdentifier;

@end

ViewsContainerController.m

//
// Created by Andrey Streltsov on 09/03/16.
// Note: need to edit before use. 

#import "ViewsContainerController.h"

#import "ViewController1.h"
#import "ViewController2.h"
#import "ViewController3.h"

#import "Additions.h"

#define kSegueIdentifier1 @"segue1"
#define kSegueIdentifier2 @"segue2"
#define kSegueIdentifier3 @"segue3"

@interface ViewsContainerController ()

@property (strong, nonatomic) NSString *currentSegueIdentifier;
@property (strong, nonatomic) NSObject<UIViewController> *viewController1;
@property (strong, nonatomic) NSObject<UIViewController> *viewController2;
@property (strong, nonatomic) NSObject<UIViewController> *viewController3;

@property (assign, nonatomic) BOOL transitionInProgress;

@property(nonatomic, strong) UIViewController *currentViewController;

@property (nonatomic, weak) IBOutlet UIActivityIndicatorView *activityIndicatorView;
@end

@implementation ViewsContainerController{

}

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.transitionInProgress = NO;
    [self.activityIndicatorView startAnimating];
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    DLog(@"");

    // Instead of creating new VCs on each seque we want to hang on to existing
    // instances if we have it. Remove the second condition of the following
    // two if statements to get new VC instances instead.
    if ([segue.identifier isEqualToString:kSegueIdentifier2]) {
        self.viewController2 = segue.destinationViewController;
    }

    if ([segue.identifier isEqualToString:kSegueIdentifier3]) {
        self.viewController3 = segue.destinationViewController;
    }

    if ([segue.identifier isEqualToString:kSegueIdentifier1]) {
        self.viewController1 = segue.destinationViewController;
    }


    // If we're going to the segment view controller view controller.
    if ([segue.identifier isEqualToString:kSegueIdentifier2]) {
        // If this is not the first time we're loading this.
        if (self.childViewControllers.count > 0) {
            [self swapFromViewController:self.childViewControllers[0]
                        toViewController:self.viewController2];
        }
        else {
            // If this is the very first time we're loading this we need to do
            // an initial load and not a swap.
            [self addChildViewController:segue.destinationViewController];
            UIView* destView = segue.destinationViewController.view;
            destView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
            destView.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
            [self.view addSubview:destView];
            [segue.destinationViewController didMoveToParentViewController:self];
            self.currentViewController = segue.destinationViewController;
        }
    }
    else if ([segue.identifier isEqualToString:kSegueIdentifier1]) {
        [self swapFromViewController:self.childViewControllers[0] toViewController:self.viewController1];
    }
    else if([segue.identifier isEqualToString:kSegueIdentifier3]) {
        [self swapFromViewController:self.childViewControllers[0] toViewController:self.viewController3];
    }
}


- (void)swapFromViewController:(UIViewController *)fromViewController
              toViewController:(UIViewController *)toViewController
{
    DLog(@"");
    

    toViewController.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);

    [fromViewController willMoveToParentViewController:nil];
    [self addChildViewController:toViewController];

    [self transitionFromViewController:fromViewController toViewController:toViewController
                              duration:0.1 options:UIViewAnimationOptionTransitionCrossDissolve
                            animations:nil completion:^(BOOL finished) {

        [fromViewController removeFromParentViewController];
        [toViewController didMoveToParentViewController:self];
        self.transitionInProgress = NO;
        self.currentViewController = toViewController;
    }];
}

- (void)switchTo:(enum eMapsViewControllerIndentifiers)viewControllerIdentifier {

    if (self.transitionInProgress) {
        return;
    }

    if([[[self class] sequeIdentifierWithMapsViewControllerIdentifier: viewControllerIdentifier] isEqualToString: self.currentSegueIdentifier])
        return;

    if(![self.childViewControllers count]){
        self.currentSegueIdentifier = kSegueIdentifier2;
        [self performSegueWithIdentifier:self.currentSegueIdentifier sender:nil];
        return;
    }

    self.transitionInProgress = YES;

    UIViewController * newViewController;
    switch(viewControllerIdentifier){

        case eSatelliteIdentifier:
            self.currentSegueIdentifier = kSegueIdentifier1;
            newViewController = self.viewController1;
            break;
        case eMapViewIdentifier:
            self.currentSegueIdentifier = kSegueIdentifier3;
            newViewController = self.viewController3;
            break;
        case eSegmentViewIdentifier:
            self.currentSegueIdentifier = kSegueIdentifier2;
            newViewController = self.viewController2;
            break;
    }


    if(newViewController) {
        [self swapFromViewController:self.currentViewController toViewController:newViewController];
        return;
    }


    [self performSegueWithIdentifier:self.currentSegueIdentifier sender:nil];
}


+ (NSString*) sequeIdentifierWithMapsViewControllerIdentifier:(enum eViewControllerIndentifiers)viewControllerIdentifier{

    NSString* result = nil;
    switch(viewControllerIdentifier){

        case eIdentifier1:
            result = kSegueIdentifier1;
            break;
        case eIdentifier3:
            result = kSegueIdentifier3;
            break;
        case eIdentifier2:
            result = kSegueIdentifier2;
            break;
    }

    return result;
}

@end