Unknown type name 'import'

AwesomeProject.zip

Description

After switching to AppDelegate.swift xcode started giving this error

Steps to reproduce

1. Update rn version from 0.76 to 0.77/0.78
2. Update AppDelegate.mm file to AppDelegate.swift
3. Delete main.m and AppDelegate.h
4. build via xcode

React Native Version

0.78.0

Affected Platforms

Build - MacOS

Output of npx @react-native-community/cli info

System:
  OS: macOS 15.2
  CPU: (8) arm64 Apple M1
  Memory: 89.20 MB / 8.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 18.18.0
    path: ~/.nvm/versions/node/v18.18.0/bin/node
  Yarn:
    version: 1.22.22
    path: /usr/local/bin/yarn
  npm:
    version: 9.8.1
    path: ~/.nvm/versions/node/v18.18.0/bin/npm
  Watchman:
    version: 4.7.0
    path: /usr/local/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /usr/local/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 24.2
      - iOS 18.2
      - macOS 15.2
      - tvOS 18.2
      - visionOS 2.2
      - watchOS 11.2
  Android SDK: Not Found
IDEs:
  Android Studio: 2020.3 AI-203.7717.56.2031.7583922
  Xcode:
    version: 16.2/16C5032a
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 11.0.1
    path: /usr/bin/javac
  Ruby:
    version: 2.6.10
    path: /usr/bin/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 15.0.1
    wanted: 15.0.1
  react:
    installed: 19.0.0
    wanted: 19.0.0
  react-native:
    installed: 0.78.0
    wanted: 0.78.0
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: false
iOS:
  hermesEnabled: true
  newArchEnabled: false

Stacktrace or Logs

AppDelegate.swift:1:1: error: unknown type name 'import'
    1 | import UIKit
AppDelegate.swift:1:13: error: expected ';' after top level declarator
    1 | import UIKit

Reproducer

git repo

Screenshots and Videos

从链接的复现用例和 AppDelegate.swift 迁移开始，然后将其与已删除的 AppDelegate.mm、main.m 和 AppDelegate.h 文件进行比较。通过 Xcode 构建项目，并追踪 Swift 文件为何被解析为另一种源代码类型；完成标准是 React Native 0.78 项目能够在没有报告中的错误的情况下构建。