Changing background color of iOS rootView

AppDelegate.m

  RCTRootView *rootView = [[RCTRootView alloc] initWithBundleURL:jsCodeLocation
                                                      moduleName:@"YourReactApp"
                                                  initialProperties:nil
                                                   launchOptions:launchOptions];
// This line
rootView.backgroundColor = [[UIColor alloc] initWithRed:0.39 green:0.58 blue:0.67 alpha:1];