I am following the tutorial given here with some of my own modification to create a Container View Controller that should hold three different View Controllers.

But when I run the app the views are not getting swapped properly and also crashes. Here is the log report:

2015-08-05 15:25:27.564 VUTEk Go[5589:327605] -[RightViewController shouldPerformSegueWithIdentifier:sender:]
2015-08-05 15:25:27.565 VUTEk Go[5589:327605] -[RightViewController prepareForSegue:sender:]
2015-08-05 15:25:27.566 VUTEk Go[5589:327605] -[LogContainerViewController prepareForSegue:sender:]
2015-08-05 15:25:29.339 VUTEk Go[5589:327605] TAB2
2015-08-05 15:25:29.340 VUTEk Go[5589:327605] -[LogContainerViewController swapViewControllers:]
2015-08-05 15:25:29.341 VUTEk Go[5589:327605] -[LogContainerViewController prepareForSegue:sender:]
2015-08-05 15:25:29.341 VUTEk Go[5589:327605] -[LogContainerViewController swapFromViewController:toViewController:]
2015-08-05 15:25:31.363 VUTEk Go[5589:327605] TAB3
2015-08-05 15:25:31.363 VUTEk Go[5589:327605] -[LogContainerViewController swapViewControllers:]
2015-08-05 15:25:31.363 VUTEk Go[5589:327605] -[LogContainerViewController swapFromViewController:toViewController:]
2015-08-05 15:25:31.407 VUTEk Go[5589:327605] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Children view controllers (null) and <StatusLogViewController: 0x7fcbac90ca30> must have a common parent view controller when calling -[UIViewController transitionFromViewController:toViewController:duration:options:animations:completion:]'

Here is my interface file:LogContainerViewController.h

#import <UIKit/UIKit.h>

@interface LogContainerViewController : UIViewController
- (void)swapViewControllers:(int) index;
@end

And my implementation file:LogContainerViewController.m

#import "LogContainerViewController.h"


#import "ErrorLogViewController.h"
#import "WarningLogViewController.h"
#import "StatusLogViewController.h"

#define SegueIdentifierFirst @"errorSegue"
#define SegueIdentifierSecond @"warningSegue"
#define SegueIdentifierThird @"statusSegue"


@interface LogContainerViewController ()
@property (strong, nonatomic) NSString *currentSegueIdentifier;
@property (strong, nonatomic) ErrorLogViewController* errorViewController;
@property (strong, nonatomic) WarningLogViewController* warningViewController;
@property (strong, nonatomic) StatusLogViewController* statusViewController;
@property (assign, nonatomic) BOOL transitionInProgress;
@end

@implementation LogContainerViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.transitionInProgress = NO;
    self.currentSegueIdentifier = SegueIdentifierFirst;
    [self performSegueWithIdentifier:self.currentSegueIdentifier sender:nil];
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    NSLog(@"%s", __PRETTY_FUNCTION__);

    // 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:SegueIdentifierFirst]) {
     self.errorViewController = segue.destinationViewController;
  }

  if ([segue.identifier isEqualToString:SegueIdentifierSecond]) {
    self.warningViewController = segue.destinationViewController;
  }
  if ([segue.identifier isEqualToString:SegueIdentifierThird]) {
    self.statusViewController = segue.destinationViewController;
  }

 // If we're going to the first view controller.
 if ([segue.identifier isEqualToString:SegueIdentifierFirst]) {
    // If this is not the first time we're loading this.
    if (self.childViewControllers.count > 0) {
        [self swapFromViewController:[self.childViewControllers objectAtIndex:0] toViewController:self.errorViewController];
    }
    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 = ((UIViewController *)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];
    }
}
// By definition the second view controller will always be swapped with the
// first one.
else if ([segue.identifier isEqualToString:SegueIdentifierSecond]) {
    [self swapFromViewController:[self.childViewControllers objectAtIndex:0] toViewController:self.warningViewController];
}
else if ([segue.identifier isEqualToString:SegueIdentifierThird]) {
    [self swapFromViewController:[self.childViewControllers objectAtIndex:0] toViewController:self.statusViewController];
}
}

- (void)swapFromViewController:(UIViewController *)fromViewController toViewController:(UIViewController *)toViewController
{
 NSLog(@"%s", __PRETTY_FUNCTION__);

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:1.0 options:UIViewAnimationOptionTransitionCrossDissolve animations:nil completion:^(BOOL finished) {
    [fromViewController removeFromParentViewController];
    [toViewController didMoveToParentViewController:self];
    self.transitionInProgress = NO;
}];
}

- (void)swapViewControllers:(int) index
{
NSLog(@"%s", __PRETTY_FUNCTION__);

if (self.transitionInProgress) {
    return;
}

self.transitionInProgress = YES;
//self.currentSegueIdentifier = ([self.currentSegueIdentifier isEqualToString:SegueIdentifierFirst]) ? SegueIdentifierSecond : SegueIdentifierFirst;

if([self.currentSegueIdentifier isEqualToString:SegueIdentifierFirst] && index==0){
    self.currentSegueIdentifier = SegueIdentifierFirst;
}else if ([self.currentSegueIdentifier isEqualToString:SegueIdentifierSecond] && index==1){
    self.currentSegueIdentifier = SegueIdentifierSecond;
}
else{
    self.currentSegueIdentifier = SegueIdentifierThird;
}




if (([self.currentSegueIdentifier isEqualToString:SegueIdentifierFirst]) && self.errorViewController && index==0) {
    [self swapFromViewController:self.warningViewController toViewController:self.errorViewController];
    return;
}
if (([self.currentSegueIdentifier isEqualToString:SegueIdentifierThird]) && self.statusViewController && index==2) {
    [self swapFromViewController:self.warningViewController toViewController:self.statusViewController];
    return;
}


if (([self.currentSegueIdentifier isEqualToString:SegueIdentifierSecond]) && self.warningViewController && index==1) {
    [self swapFromViewController:self.errorViewController toViewController:self.warningViewController];
    return;
}

if (([self.currentSegueIdentifier isEqualToString:SegueIdentifierThird]) && self.statusViewController && index==2) {
    [self swapFromViewController:self.errorViewController toViewController:self.statusViewController];
    return;
}
if (([self.currentSegueIdentifier isEqualToString:SegueIdentifierFirst]) && self.errorViewController && index==0) {
    [self swapFromViewController:self.warningViewController toViewController:self.errorViewController];
    return;
}
if (([self.currentSegueIdentifier isEqualToString:SegueIdentifierSecond]) && self.errorViewController && index==1) {
    [self swapFromViewController:self.statusViewController toViewController:self.warningViewController];
    return;
}



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

@end

I want to load these view when I select a segment in my UISegmented View. The action for that is :

- (IBAction)printerLogSegmentChanged:(id)sender {
UISegmentedControl *s = (UISegmentedControl *)sender;

if (s.selectedSegmentIndex == 0)
{
    NSLog(@"TAB1");
    [self.containerViewController swapViewControllers:0];
}
else if (s.selectedSegmentIndex == 1){
    NSLog(@"TAB2");
    [self.containerViewController swapViewControllers:1];
}
else if (s.selectedSegmentIndex == 2){
    NSLog(@"TAB3");
    [self.containerViewController swapViewControllers:2];
}
else{
    NSLog(@"TAB NOT Working");
}

}

But I think there is something wrong with logic of - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender; that I am using.

Any help will really be appreciated as I have been stuck on this for more than two hours and all similar question couldn't help me.

I am sharing a screen shot of my app

As you can see in the above screenshot that it swaps the wrong child view and sometime also crashes.

Thanks in advance!

via Chebli Mohamed