Launch iOS simulator from Xcode and getting a black screen, followed by Xcode hanging and unable to stop tasks

I'm having trouble running my basic iPhone application (while going through the Stanford iTunes CS193p lectures) in the iOS simulator.

I've been searching for a while (both Google and SO), but unable to find a solution so far. There are many similar bugs, but the solutions don't seem to fix this.

In Xcode I click "run". It compiles and builds successfully, launches iOS simulator but it never gets to loading the app. Only the status bar at the top. With a black screen.

I've only written very basic code (following along with the lectures) and can't get past this problem.

To confuse matters more, I wrote a web wrapper (UIWebView) before these lectures and this works fine. But there is barely any difference in the code. All new apps I create from scratch all fail with the same black screen problem.

If I hit the home button on the simulator and launch the app, it will display. But Xcode doesn't seem to know what's going on.

It's as if Xcode has lost the ability to talk to iOS Simulator and assumes it's running (even if I quit iOS simulator). I try and quit Xcode, and it asks me to stop the tasks. Then it just hangs. So I have to force restart to get out of Xcode.

I'm using: OSX 10.8.2 Xcode 4.5.2 iOS Simulator 6.0

CalculatorAppDelegate.h

#import <UIKit/UIKit.h>

@interface CalculatorAppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end

CalculatorAppDelegate.m

#import "CalculatorAppDelegate.h"

@implementation CalculatorAppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions (NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application
{
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. 
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{
// Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}

- (void)applicationDidBecomeActive:(UIApplication *)application
{
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}

- (void)applicationWillTerminate:(UIApplication *)application
{
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}

@end

CalculatorViewController.h

#import <UIKit/UIKit.h>

@interface CalculatorViewController : UIViewController
@property (weak, nonatomic) IBOutlet UILabel *display;

@end

CalculatorViewController.m

#import "CalculatorViewController.h"

@implementation CalculatorViewController

@synthesize display = _display;

- (IBAction)digitPressed:(UIButton *)sender
{
    NSString *digit = [sender currentTitle];
NSLog(@"digit pressed = %@", digit);
}

@end

Surprisingly, what worked for me was going to iOS Simulator menu, and pressing "Reset Content and Settings". (in iOS 13, its under Hardware)