Xcode 12.5.1中FirebaseSessions Swift类型转换错误求助

问题描述 #

按教程将Firebase集成到React Native iOS应用后，编译时出现类型转换错误，错误指向SessionStartEvent.swift中的pb_istream_from_buffer调用，具体错误信息：

Cannot convert value of type 'UnsafeRawPointer' to expected argument type 'UnsafePointer<pb_byte_t>?' (aka 'Optional')

相关代码片段 #

Podfile配置

require_relative '../node_modules/@react-native-community/cli-platform-ios/native_modules'

platform :ios, min_ios_version_supported
prepare_react_native_project!

flipper_config = ENV['NO_FLIPPER'] == "1" ? FlipperConfiguration.disabled : FlipperConfiguration.enabled

linkage = ENV['USE_FRAMEWORKS']
if linkage != nil
  Pod::UI.puts "Configuring Pod with #{linkage}ally linked Frameworks".green
  use_frameworks! :linkage => linkage.to_sym
end

target 'stllrmobile' do
  config = use_native_modules!

  use_frameworks! :linkage => :static
  #$RNFirebaseAsStaticFramework = true 

  flags = get_default_flags()

  use_react_native!(
    :path => config[:reactNativePath],
    :hermes_enabled => flags[:hermes_enabled],
    :fabric_enabled => flags[:fabric_enabled],
    #:flipper_configuration => flipper_config,
    :app_path => "#{Pod::Config.instance.installation_root}/.."
  )

  target 'stllrmobileTests' do
    inherit! :complete
  end

  post_install do |installer|
    react_native_post_install(
      installer,
      :mac_catalyst_enabled => false
    )
    __apply_Xcode_12_5_M1_post_install_workaround(installer)
  end
end

出错的Swift代码（SessionStartEvent.swift）

func encodeDecodeEvent() -> firebase_appquality_sessions_SessionEvent {
    let transportBytes = self.transportBytes()
    var proto = firebase_appquality_sessions_SessionEvent()
    var fields = firebase_appquality_sessions_SessionEvent_fields

    let bytes = (transportBytes as NSData).bytes
    var istream: pb_istream_t = pb_istream_from_buffer(bytes, transportBytes.count)

    if !pb_decode(&istream, &fields.0, &proto) {
      let errorMessage = FIRSESPBGetError(istream)
      if errorMessage.count > 0 {
        Logger.logError("Session Event failed to decode transportBytes: \(errorMessage)")
      }
    }
    return proto
  }

错误发生在这一行：

var istream: pb_istream_t = pb_istream_from_buffer(bytes, transportBytes.count)

解决方法 #

1. 修复Swift代码的类型转换 #

(transportBytes as NSData).bytes返回的是UnsafeRawPointer，而pb_istream_from_buffer需要的是UnsafePointer<pb_byte_t>，需显式转换类型：

替换原有的let bytes = ...行：

let bytes = (transportBytes as NSData).bytes.assumingMemoryBound(to: pb_byte_t.self)
var istream: pb_istream_t = pb_istream_from_buffer(bytes, transportBytes.count)

或者使用Swift原生Data的安全API（更推荐）：

func encodeDecodeEvent() -> firebase_appquality_sessions_SessionEvent {
    let transportBytes = self.transportBytes()
    var proto = firebase_appquality_sessions_SessionEvent()
    var fields = firebase_appquality_sessions_SessionEvent_fields

    var istream: pb_istream_t = pb_istream_from_buffer(nil, 0)
    transportBytes.withUnsafeBytes { buffer in
        guard let baseAddress = buffer.baseAddress else {
            Logger.logError("Failed to get buffer address for session event")
            return
        }
        let bytes = baseAddress.assumingMemoryBound(to: pb_byte_t.self)
        istream = pb_istream_from_buffer(bytes, transportBytes.count)
    }

    if !pb_decode(&istream, &fields.0, &proto) {
      let errorMessage = FIRSESPBGetError(istream)
      if errorMessage.count > 0 {
        Logger.logError("Session Event failed to decode transportBytes: \(errorMessage)")
      }
    }
    return proto
}

2. 调整Podfile配置 #

取消$RNFirebaseAsStaticFramework = true的注释，确保Firebase框架以静态方式链接：

# 取消注释这一行
$RNFirebaseAsStaticFramework = true 

然后重新执行pod安装：

cd ios && pod install --repo-update

3. 清理缓存并重新编译 #

• 在Xcode中按下Cmd+Shift+K清理项目缓存
• 删除DerivedData目录（可通过Xcode偏好设置 -> 位置 找到路径后手动删除）
• 重新运行项目

内容的提问来源于stack exchange，提问作者user3054529