UINavigationController - A Simple Example

Recently I decided to use the UINavigationController class so I could push and pop sub views for easy navigation. As usual, all I wanted was a simple clean example to help me get started and of course all the examples I found were either so simple they were useless or they were trying to do much more than the simple example I wanted, as always, here is what I came up with (with base code being copied from some simple example).

This example shows how to navigate between 3 sub views. It includes forward and backward buttons where appropriate.

First the .h file ...

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
{
    UINavigationController * navController;
    UIBarButtonItem *nextButtonOne;
    UIBarButtonItem *nextButtonTwo;
    UIBarButtonItem *prevButtonTwo;
    UIBarButtonItem *prevButtonThree;
    UIViewController *one;
    UIViewController *two;
    UIViewController *three;
    int currentView;
}

@property (nonatomic, retain)UINavigationController * navController;
@property (nonatomic, retain)UIBarButtonItem *nextButtonOne;
@property (nonatomic, retain)UIBarButtonItem *nextButtonTwo;
@property (nonatomic, retain)UIBarButtonItem *prevButtonTwo;
@property (nonatomic, retain)UIBarButtonItem *prevButtonThree;
@property (nonatomic, retain)UIViewController *one;
@property (nonatomic, retain)UIViewController *two;
@property (nonatomic, retain)UIViewController *three;
@property (atomic, assign)int currentView;

- (IBAction)handleNextButton:(id)sender;
- (IBAction)handlePrevButton:(id)sender;

@end

And next, the .m file ...

#import "ViewController.h"

@implementation ViewController

@synthesize navController, nextButtonOne, nextButtonTwo, currentView;
@synthesize prevButtonTwo, prevButtonThree, one, two, three;

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (IBAction)handleNextButton:(id)sender {
    if (currentView == 0){
        [navController pushViewController:two animated:YES];
    }else{
        [navController pushViewController:three animated:YES];
    }
    currentView++;
}

- (IBAction)handlePrevButton:(id)sender {
    [navController popViewControllerAnimated:YES];
    currentView--;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    one = [[UIViewController alloc] init];

    [one.view setBackgroundColor:[UIColor yellowColor]];
    [one setTitle:@"One"];
    
    nextButtonOne = [[UIBarButtonItem alloc]
                  initWithTitle:@"Two"
                  style:UIBarButtonItemStyleBordered
                  target:self
                  action:@selector(handleNextButton:)];
    
    [[one navigationItem] setRightBarButtonItem:nextButtonOne];

    
    navController = [[UINavigationController alloc] initWithRootViewController:one];
    // here 's the key to the whole thing: we're adding the navController's view to the 
    // self.view, NOT the one.view! So one would be the home page of the app (or something)
    [self.view addSubview:navController.view];
    
    two = [[UIViewController alloc] init];
    [two.view setBackgroundColor:[UIColor blueColor]];
    [two setTitle:@"Two"];
    
    nextButtonTwo = [[UIBarButtonItem alloc]
                     initWithTitle:@"3"
                     style:UIBarButtonItemStyleBordered
                     target:self
                     action:@selector(handleNextButton:)];
    
    prevButtonTwo = [[UIBarButtonItem alloc]
                     initWithTitle:@"1"
                     style:UIBarButtonItemStyleBordered
                     target:self
                     action:@selector(handlePrevButton:)];
    
    [[two navigationItem] setLeftBarButtonItem:prevButtonTwo];
    [[two navigationItem] setRightBarButtonItem:nextButtonTwo];
    
    [navController pushViewController:two animated:YES];
    
    three = [[UIViewController alloc] init];
    [three.view setBackgroundColor:[UIColor redColor]];
    [three setTitle:@"Three"];
    
    prevButtonThree = [[UIBarButtonItem alloc]
                     initWithTitle:@"2"
                     style:UIBarButtonItemStyleBordered
                     target:self
                     action:@selector(handlePrevButton:)];
        
    [[three navigationItem] setLeftBarButtonItem:prevButtonThree];
    [navController pushViewController:three animated:YES];
        
    currentView = 2;
}


- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
}

- (void)viewWillDisappear:(BOOL)animated
{
 [super viewWillDisappear:animated];
}

- (void)viewDidDisappear:(BOOL)animated
{
 [super viewDidDisappear:animated];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
    } else {
        return YES;
    }
}

@end

Its that simple :-)