Keep same view(s) in multiple controllers - ios

Question

I'm currently developing an app that has three buttons at the bottom of the layout (for customization reasons I couldn't use TabBar Controller or Segmented Control).
When I click one of these buttons, a new view should show up and inherite the buttons bar, along with its state (buttons can be in selected or unselected state).
I'm completely new to iOS development, so I tried following this guide (http://www.thinkandbuild.it/working-with-custom-container-view-controllers/), but problem is when I click a button, child view doesn't show up.
ContainerViewController.h
#interface ContainerViewController : UIViewController
#property (weak, nonatomic) IBOutlet UIButton *firstButton;
#property (weak, nonatomic) IBOutlet UIButton *secondButton;
#property (weak, nonatomic) IBOutlet UIButton *thirdButton;
#property (weak, nonatomic) IBOutlet UIView *detailView;
- (IBAction)click:(id)sender;
#end
ContainerViewController.m
#import "ContainerViewController.h"
#import "FirstViewController.h"
#interface ContainerViewController ()
#property UIContainerViewController *currentDetailContainerViewController;
#end
#implementation ContainerViewController
#synthesize firstButton, secondButton, thirdButton;
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)click:(id)sender
{
// switch buttons state
// ...
[self addDetailController:sender];
}
- (void)presentDetailController:(UIContainerViewController*)detailVC{
//0. Remove the current Detail View Controller showed
if(self.currentDetailContainerViewController){
[self removeCurrentDetailContainerViewController];
}
//1. Add the detail controller as child of the container
[self addChildContainerViewController:detailVC];
//2. Define the detail controller's view size
detailVC.view.frame = [self frameForDetailController];
//3. Add the Detail controller's view to the Container's detail view and save a reference to the detail View Controller
[self.detailView addSubview:detailVC.view];
self.currentDetailContainerViewController = detailVC;
//4. Complete the add flow calling the function didMoveToParentContainerViewController
[detailVC didMoveToParentContainerViewController:self];
}
- (void)removeCurrentDetailContainerViewController{
//1. Call the willMoveToParentContainerViewController with nil
// This is the last method where your detailContainerViewController can perform some operations before neing removed
[self.currentDetailContainerViewController willMoveToParentContainerViewController:nil];
//2. Remove the DetailContainerViewController's view from the Container
[self.currentDetailContainerViewController.view removeFromSuperview];
//3. Update the hierarchy"
// Automatically the method didMoveToParentContainerViewController: will be called on the detailContainerViewController)
[self.currentDetailContainerViewController removeFromParentContainerViewController];
}
- (CGRect)frameForDetailController{
CGRect detailFrame = self.detailView.bounds;
return detailFrame;
}
- (void)addDetailController:(id)sender {
FirstViewController *detailVC = [[FirstViewController alloc]initWithString:#"First view"];
[self presentDetailController:detailVC];
}
#end
FirstViewController.h
#import <UIKit/UIKit.h>
#class ContainerViewController;
#interface FirstViewController : UIViewController
#property (weak, nonatomic) IBOutlet UILabel *label;
- (id)initWithString:(NSString*)string;
#end
FirstViewController.m
#import "FirstViewController.h"
#interface FirstViewController (){
NSString *text;
}
#end
#implementation FirstViewController
- (id)initWithString:(NSString*)string {
self = [super init];
if(self){
text = string;
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.label.text = text;
}
#end