小编cuo*_*gtd的帖子

将我的应用程序更新到react-native v0.66.0后，如果启用了hermes，我会不断收到此错误。我尝试删除 DerivedData 文件夹、podfile podfile.lock...但没有任何帮助

终端输出

duplicate symbol 'folly::exception_wrapper::from_exception_ptr(std::exception_ptr&&)' in:
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/Flipper-Folly/libFlipper-Folly.a(ExceptionWrapper.o)
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/RCT-Folly/libRCT-Folly.a(ExceptionWrapper.o)
duplicate symbol 'folly::exception_wrapper::from_exception_ptr(std::exception_ptr const&)' in:
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/Flipper-Folly/libFlipper-Folly.a(ExceptionWrapper.o)
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/RCT-Folly/libRCT-Folly.a(ExceptionWrapper.o)
duplicate symbol 'folly::exception_wrapper::onNoExceptionError(char const*)' in:
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/Flipper-Folly/libFlipper-Folly.a(ExceptionWrapper.o)
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/RCT-Folly/libRCT-Folly.a(ExceptionWrapper.o)
duplicate symbol 'folly::exceptionStr(folly::exception_wrapper const&)' in:
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/Flipper-Folly/libFlipper-Folly.a(ExceptionWrapper.o)
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/RCT-Folly/libRCT-Folly.a(ExceptionWrapper.o)
duplicate symbol 'folly::exception_wrapper::uninit_' in:
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/Flipper-Folly/libFlipper-Folly.a(ExceptionWrapper.o)
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/RCT-Folly/libRCT-Folly.a(ExceptionWrapper.o)
duplicate symbol 'folly::exception_wrapper::ExceptionPtr::ops_' in:
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/Flipper-Folly/libFlipper-Folly.a(ExceptionWrapper.o)
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/RCT-Folly/libRCT-Folly.a(ExceptionWrapper.o)
duplicate symbol 'folly::exception_wrapper::SharedPtr::ops_' in:
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/Flipper-Folly/libFlipper-Folly.a(ExceptionWrapper.o)
    /Users/cuongtd/Library/Developer/Xcode/DerivedData/MyApp-ekbbcdnefrapxuertuowclstsjop/Build/Products/Debug-iphonesimulator/RCT-Folly/libRCT-Folly.a(ExceptionWrapper.o)
ld: 7 duplicate symbols for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

ios/podfile

platform :ios, '11.0'
require_relative '../node_modules/react-native/scripts/react_native_pods'
require_relative '../node_modules/@react-native-community/cli-platform-ios/native_modules' …

假设我的应用程序如下所示

@Composable
fun AppNavigation() {
    val navController = rememberNavController()

    NavHost(navController, startDestination = Route.Home.route) {
        /// other composes
        composable("Home") { HomeCompose(navController) }
    }
}

@Composable
fun HomeCompose(navController: NavHostController) {
    ChildCompose(navController)
}

@Composable
fun ChildCompose(navController: NavHostController) {
    navController.navigate("")
}

我想访问嵌套可组合项中的 navController 进行导航，但我不想将 navController 从父可组合项传递到子可组合项，如上所述

无论如何，是否可以从 NavHost 内的任何位置访问 navController，而无需通过可组合层次结构传递它

编辑：现在，我可以使用 CompositionLocalProvider 访问嵌套组合中的 navController，如下所示

val AppNavController = compositionLocalOf<NavHostController>() { error("NavHostController error") }

@Composable
fun AppNavigation() {
    val navController = rememberNavController()
    CompositionLocalProvider(
        AppNavController provides navController
    ) {
        NavHost(navController, startDestination = Route.Home.route) {
            /// other composes …

我正在创建一个带有底部导航和抽屉的简单应用程序。

我将所有屏幕都包裹在带有顶栏和底栏的 Scaffold 中。我想隐藏特定屏幕上的顶部栏和底部栏。有谁知道如何实现

这是设置导航的代码。

val navController = rememberNavController()
val scaffoldState = rememberScaffoldState(rememberDrawerState(DrawerValue.Closed))

Scaffold(
    bottomBar = {
        AppBottomBar(navController)
    },
    topBar = {
        AppTopBar(scaffoldState)
    },
    drawerContent = {
        DrawerContent(navController, scaffoldState)
    },
    scaffoldState = scaffoldState
) {
    // ovoid bottom bar overlay content
    Column(modifier = Modifier.padding(bottom = 58.dp)) {
        AppNavigation(navController)
    }
}

AppNavigation包含NavHost用于导航到屏幕

假设我的代码如下所示

@Composable
fun ExampleList() {
    val tickers by exampleViewModel.tickers.observeAsState()
    LazyColumn() {
        items(items = tickers) { ticker ->
            ExampleItem(ticker)
        }
    }
}
@Composable
fun ExampleItem(ticker: Ticker) {
    Text(text= ticker.lastPrice)
}

每次更新股票代码时，是否都可以在ExampleItem Compose 中获取股票代码的先前值？
我想知道 React Native 中是否有类似 componentDidUpdate 的东西