React Native项目iOS端Xcode运行报错及Mac端加载失败求助

Hey there, let's break down these two React Native headaches you're dealing with—they're pretty typical when moving between Windows/Mac or iOS/Android, so let's work through each one:

问题1：iOS设备上通过Xcode运行React Native项目时出现错误代码-999 #

Error -999 usually ties into network or cache issues. Here are the fixes I'd recommend trying in order:

• Check App Transport Security (ATS) settings: Open your project's Info.plist in Xcode, add a new entry for App Transport Security Settings, then add a sub-entry Allow Arbitrary Loads and set it to YES. This bypasses strict network restrictions that might block the dev server connection (note: this is only for debug builds—lock this down for release versions).
• Clear React Native's cache: Run this in your project directory to reset the packager cache:

  npm start -- --reset-cache
  # Or if you use yarn
  yarn start --reset-cache
  

• Fully restart your tools: Quit Xcode completely, shut down the iOS simulator/device, kill any running Node processes, then restart everything. Sometimes stuck processes just need a fresh start.
• Verify port 8081 isn't blocked: Use this command to check if anything's using the default dev port:

  lsof -i :8081
  

  If you see results, kill the process with:

  kill -9 <PID>
  

  Replace <PID> with the process ID from the previous output.

问题2：Windows开发安卓后，Mac上Xcode运行时bundle无法连接开发服务器 #

Since you've already tried killing 8081 processes and modifying localhost, let's try these less obvious fixes:

• Check Mac's firewall settings: Open System Settings → Network → Firewall → Options. Make sure node or the React Native Packager is allowed to receive incoming connections. If it's not listed, click the "+" button, navigate to your Node installation (usually /usr/local/bin/node), and add it.
• Use your local IP instead of localhost: Sometimes localhost resolution flubs up across networks. First, find your Mac's local IP (run ifconfig | grep inet in Terminal, look for the inet line under your WiFi adapter). Then:
  1. Start the packager with:

     npm start -- --host 0.0.0.0
     

  2. In Xcode, open your project's debug configuration (or edit AppDelegate.m if you're using an older React Native version) and replace localhost with your local IP. For example:

     jsCodeLocation = [NSURL URLWithString:@"http://192.168.1.100:8081/index.bundle?platform=ios&dev=true"];
     

• Reinstall dependencies: Windows and Mac can have subtle differences in node_modules. Delete your node_modules folder, package-lock.json (or yarn.lock), then run:

  npm install
  # Or yarn install
  

  This ensures you have Mac-compatible dependencies.
• Confirm your device is on the same network: If you're using a physical iOS device, make sure it's connected to the same WiFi network as your Mac. If you're using a simulator, double-check that it's not using a virtual network isolated from your Mac.

内容的提问来源于stack exchange，提问作者priti narang