RCTRootView *rootView = [[RCTRootView alloc] initWithBundleURL:jsCodeLocation
                                                      moduleName:@"Demo App"
                                                  initialProperties:nil
                                                   launchOptions:launchOptions];

rootView.backgroundColor = [[UIColor alloc] initWithRed:0.52 green:0.52 blue:0.52 alpha:1];