// AppDelegate.m

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
  if (isRunningTests()) return YES;
  // ...
  return YES;
}

BOOL isRunningTests(void)
{
  NSDictionary* environment = [[NSProcessInfo processInfo] environment];
  NSString* injectBundle = environment[@"XCInjectBundle"];
  return [[injectBundle pathExtension] isEqualToString:@"xctest"];
}

- (instancetype)init
{
  self = [super init];
  if (self) {
    if (isRunningTests()){
      // This bundle has unit tests injected. Let's not really start the app to avoid interfering with the tests.
     id infoDictionary = [[NSBundle mainBundle] infoDictionary];
     [infoDictionary setValue:@"UnitTest" forKey:@"UIMainStoryboardFile"];
    }
  }
  return self;
}
@end