React Native如何消除启动时白屏的方法

#import <Foundation/Foundation.h>
 #import "RCTBridgeModule.h"
 @interface SplashScreen : NSObject<RCTBridgeModule>

 @end

#import "SplashScreen.h"
 @implementation SplashScreen

 RCT_EXPORT_MODULE();

 RCT_EXPORT_METHOD(close){
  [[NSNotificationCenter defaultCenter] postNotificationName:@"Notification_CLOSE_SPLASH_SCREEN" object:nil];
 }
 @end

@interface AppDelegate ()
 {
  UIImageView *splashImage;
 }
 @end

 @implementation AppDelegate

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(closeSplashImage) name:"Notification_CLOSE_SPLASH_SCREEN" object:nil];

   ...
   [self autoSplashScreen];//写在 return YES 之前，其他代码之后
   return YES;
 }
 -(void)autoSplashScreen {
  if (!splashImage) {
   splashImage = [[UIImageView alloc]initWithFrame:[UIScreen mainScreen].bounds];
  }
  if (IPHONESCREEN3p5) {
   [splashImage setImage:[UIImage imageNamed:@"launch4"]];
  }else if (IPHONESCREEN4){
   [splashImage setImage:[UIImage imageNamed:@"launch5"]];
  }else if (IPHONESCREEN4p7){
   [splashImage setImage:[UIImage imageNamed:@"launch6"]];
  }else if (IPHONESCREEN5p5){
   [splashImage setImage:[UIImage imageNamed:@"launch7"]];
  }
  [self.window addSubview:splashImage];
 }
 -(void)closeSplashImage {
    dispatch_sync(dispatch_get_main_queue(), ^{
     [UIView animateWithDuration:0.5 animations:^{
      splashImage.alpha = 0;
     } completion:^(BOOL finished){
      [splashImage removeFromSuperview];
     }];
    });
 }

if (Platform.OS === 'ios') {
   NativeModules.SplashScreen.close();
 };