在 iOS 模拟器中启动 Flutter 应用程序时出错

我在 iOS 模拟器上启动 Flutter 应用程序时遇到问题。从下面的错误输出来看，这个问题似乎与本地主机连接等有关，但我无法找到如何修复它。

我正在运行 MacOS Catalina 版本 10.15.6 (19G73)。 iOS模拟器版本11.6（921.9.1）。 VSCode 是我的 IDE。

该应用程序在 Android 模拟器上启动并运行良好。

以下是 VSCode 终端的错误输出：

Launching lib/main.dart on iPhone SE (2nd generation) in debug mode...
Running Xcode build...                                                  
 └─Compiling, linking and signing...                         6.7s
Xcode build done.                                           16.7s
Connecting to the VM Service is taking longer than expected...
Still attempting to connect to the VM Service...
If you do NOT see the Flutter application running, it might have crashed. The device logs (e.g. from adb or XCode) might have more details.
If you do see the Flutter application running on the device, try re-running with --host-vmservice-port to use a specific port known to be available.
Exception attempting to connect to the VM Service: SocketException: OS Error: Connection refused, errno = 61, address = 127.0.0.1, port = 51838
This was attempt #50. Will retry in 0:00:01.600000.
Exception attempting to connect to the VM Service: SocketException: OS Error: Connection refused, errno = 61, address = 127.0.0.1, port = 51970
This was attempt #100. Will retry in 0:00:01.600000.
Exception attempting to connect to the VM Service: SocketException: OS Error: Connection refused, errno = 61, address = 127.0.0.1, port = 52119
This was attempt #150. Will retry in 0:00:01.600000.
Exception attempting to connect to the VM Service: SocketException: OS Error: Connection refused, errno = 61, address = 127.0.0.1, port = 52347
This was attempt #200. Will retry in 0:00:01.600000.
^C%

我有同样的问题，因为Firebase。 我通过反转我的 2 行来解决我的问题AppDelegate.swift file:

FirebaseApp.configure() // Should be first
GeneratedPluginRegistrant.register(with: self) // Should be second

我的非工作文件是这个

import UIKit
import Flutter
import Firebase

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    GeneratedPluginRegistrant.register(with: self) // <- Don't do this
    FirebaseApp.configure()   // <- Don't do this
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}

我的工作文件是：

import UIKit
import Flutter
import Firebase

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    FirebaseApp.configure()   // <- Do this
    GeneratedPluginRegistrant.register(with: self) // <- Do this
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}