如何在博览会加载时检查某些内容？答案

【问题标题】：How to check something while loading in expo?如何在博览会加载时检查某些内容？
【发布时间】：2022-01-10 16:34:17
【问题描述】：

我想在加载初始屏幕时检查访问令牌是否存在。世博会怎么做？

【问题讨论】：

文档在这个主题上非常扎实：docs.expo.dev/versions/latest/sdk/splash-screen

标签： javascript react-native expo access-token splash-screen

【解决方案1】：

I found the solution :-)    
  ``// import....
    import * as SplashScreen from 'expo-splash-screen';
    //.......
    //.......function
    const [appIsReady, setAppIsReady] = useState(false);
    //.......
    useEffect(()=>{
        async function prepare() {
          try {
            await SplashScreen.preventAutoHideAsync();
            await isUser();  // checking for token availability
            await new Promise(resolve => setTimeout(resolve, 2000));
          } catch (e) {
            console.log(e);
          } finally {
            setAppIsReady(true);
          }
        };
        prepare();
      },[]);
    
    
      const onLayoutRootView = useCallback(async () => {
        if (appIsReady) {
          await SplashScreen.hideAsync();
        }
      }, [appIsReady]);
    
      if (!appIsReady) {
        return null;
      };
    
    return (
        <NavigationContainer>
          <View style={{flex:1,backgroundColor:"#e0ab24"}} onLayout= 
           {onLayoutRootView}>
          //.....(navigator)
          //....
          </View>
        </NavigationContainer>``

关注文档：https://docs.expo.dev/versions/latest/sdk/splash-screen/

【讨论】：