How to set Root View Controller programatically in Objective C? - ios

Question

I am a newbie in iOS Development trying to learn how to create and set views programmatically.
i am trying to do swift statement in Obj-C
window?.rootViewController = UINavigationController(rootViewController : ViewController())
Project: Single View Application . Trying to link default Created ViewController.h
As per Krunals Answer i updated code but Navigation Controller is not shown in simulator
Cmd+Click on controller does not navigate to ViewController File
#import "AppDelegate.h"
#import "ViewController.h"
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
UIScreen *screen=[[UIScreen alloc]init];
UIWindow *window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.window.makeKeyAndVisible;
ViewController *controller = [[ViewController alloc] init];
window.rootViewController = [[UINavigationController alloc] initWithRootViewController:controller] ;

Answer 1

Initialise your view controller ViewController before you add (use as root controller of navigation) into navigation controller stack.
Here is sample code to initialise simple view controller
UIViewController *controller = [[UIViewController alloc] init];
Here is sample code to initialise using storyboard
ViewController *controller = [[UIStoryboard storyboardWithName:#"Main" bundle:nil] instantiateViewControllerWithIdentifier:#"<ViewController - string identifier of your view controller>"];
Here is sample code to initialise using NIB/Bundle
ViewController *controller = [[ViewController alloc] initWithNibName:#"<ViewController - string NIB name>>" bundle:nil];
According to your code and following comment try this code only (remove other codes from your app delegate launch):
// make sure your NIB name is 'ViewController'
ViewController *controller = [[ViewController alloc] initWithNibName:#"ViewController" bundle:nil];
if (controller != nil) {
self.window.rootViewController = [[UINavigationController alloc] initWithRootViewController: controller];
self.window.makeKeyAndVisible;
} else {
//print - your view controller is nil
}

Answer 2

Thanks to Krunal for detailed answer .
Thanks to dan for support
i found issue instead of self.window.rootViewController , i typed window.rootViewController.
setting self.window.rootViewController solved issue.
i dont know difference between self.window.rootViewController and window.rootViewController and reason for issue.
If some one knows answer please provide answer on comment
#import "AppDelegate.h"
#import "ViewController.h"
#interface AppDelegate ()
#end
#implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
UIScreen *screen=[[UIScreen alloc]init];
UIWindow *window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.window.makeKeyAndVisible;
ViewController *controller = [[ViewController alloc] init];
self.window.rootViewController = [[UINavigationController alloc] initWithRootViewController:controller] ;

Answer 3

Delele the file Main.storyboard and let the Main interface option empty before you do it.
And add this code:
self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
self.window.backgroundColor = [UIColor whiteColor];
ViewController *vc = [[ViewController alloc] init];
UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:vc];
self.window.rootViewController = nav;
[self.window makeKeyAndVisible];
UPDATE: If you want to use storyboard with UINavigationController, try this:

Answer 4

Adding UIViewController and adding with UINavigationController
UIStoryboard *storyboard = self.window.rootViewController.storyboard;
UIViewController *rootViewController= [storyboard instantiateViewControllerWithIdentifier:kIdentifier];
[self setRootViewController:rootViewController];
#pragma mark - Set RootView Controller
-(void)setRootViewController:(UIViewController *)rootViewController {
self.window.rootViewController = rootViewController;
[self.window makeKeyAndVisible];
}
UIStoryboard *storyboard = self.window.rootViewController.storyboard;
UIViewController *rootViewController= [storyboard instantiateViewControllerWithIdentifier:kIdentifier];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:rootViewController];
[self setRootViewController:navController];
-(void)setRootViewController:(UINavigationController *)rootViewController {
self.window.rootViewController = rootViewController;
[self.window makeKeyAndVisible];
}