Setting the view programmatically - objective-c

Question

I am trying to set my project without using storyboards in xcode and with objective c.
My appDelegate:
.h
#import <UIKit/UIKit.h>
#import "ViewController.h"
#interface AppDelegate : UIResponder <UIApplicationDelegate>
#property (strong, nonatomic) UIWindow *window;
#end
.m
#import "AppDelegate.h"
#interface AppDelegate ()
#end
#implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
ViewController *vc = [[ViewController alloc] init];
self.window.rootViewController = vc;
return YES;
}
etc...
My viewController file:
.m
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
UIView *view = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
view.backgroundColor = [UIColor redColor];
[self.view addSubview:view];
}
I think my code is right and we should have a red screen when I run it, but I only get a black screen. Can someone tell me if I have forgotten something or is it something to do with the project settings. Thanks.

Answer 1

Add
self.window = [[UIWindow alloc] initWithFrame:UIScreen.mainScreen.bounds];
to your application:didFinishLaunchingWithOptions:

Answer 2

You are missing two steps.
Initialize the window:
self.window = [[UIWindow alloc] initWithFrame:UIScreen.mainScreen.bounds];
Make the window key & visible:
[self.window makeKeyAndVisible];
So all together, your code should look like this:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Initialize the window
self.window = [[UIWindow alloc] initWithFrame:UIScreen.mainScreen.bounds];
// Add the view controller to the window
ViewController *vc = [[ViewController alloc] init];
self.window.rootViewController = vc;
// Make window key & visible
[self.window makeKeyAndVisible];
return YES;
}