Flutter Plugin - Value Of type "xxx" has no member "xxx"

I write a flutter iOS plugin which using Google Machine learning framework 'ML Kit'. The iOS plugin language is swift. Plugin has 3 files.MLKitPlugin.h, MLKitPlugin.m, SwiftMLKitPlugin.swift, these 3 file are generated automaticly when I am creating this plugin.
This is code of iOS plugin .podspec file:

Pod::Spec.new do |s|  s.name             = 'image_origin_enhancer'  s.version          = '0.0.1'  s.summary          = 'image origin enhancer'  s.description      = <<-DESCimage origin enhancer                       DESC  s.homepage         = 'http://example.com'  s.license          = { :file => '../LICENSE' }  s.author           = { 'Your Company' => 'email@example.com' }  s.source           = { :path => '.' }  s.source_files = 'Classes/**/*'  s.static_framework = true  s.dependency 'Flutter'  # here import Google ML Kit framework  s.dependency 'GoogleMLKit/PoseDetection', '2.6.0'  # Flutter.framework does not contain a i386 slice.  s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386' }  s.swift_version = '5.0'end

Code in MLKitPlugin.m is very simple:

#import "MLKitPlugin.h"#if __has_include(<ml_kit/ml_kit-Swift.h>)#import <ml_kit/ml_kit-Swift.h>#else// Support project import fallback if the generated compatibility header// is not copied when this plugin is created as a library.// https://forums.swift.org/t/swift-static-libraries-dont-copy-generated-objective-c-header/19816#import "ml_kit-Swift.h"#endif@implementation MLKitPlugin+ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {  [SwiftMLKitPlugin registerWithRegistrar:registrar];}

Code in SwiftMLKitPlugin.swift

import Flutterimport UIKitimport MLImageimport MLKitPoseDetectionimport MLKitPoseDetectionCommonpublic class SwiftMLKitPlugin: NSObject, FlutterPlugin {     var poseDetector: PoseDetector? = nil  // define PoseDetector from MLKit framework  public static func register(with registrar: FlutterPluginRegistrar) {    let channel = FlutterMethodChannel(name: "XXX", binaryMessenger: registrar.messenger())    let instance = SwiftMLKitPlugin()    registrar.addMethodCallDelegate(instance, channel: channel)  }    override init(){        super.init();        let options = PoseDetectorOptions()        options.detectorMode = .singleImage        self.poseDetector = PoseDetector.poseDetector(options: options)    }  public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {      if "detectPose" == call.method {          if let poseDetector = self.poseDetector {            poseDetector.process(MLImage(image:UIImage(name:""))) // this is the error code { poses, error in              guard error == nil, let poses = poses, !poses.isEmpty else {                let errorString = error?.localizedDescription ?? Constants.detectionNoResultsMessage                return              }            }          }          result("success")      }  }}

poseDetector.process(MLImage(image:UIImage(name:""))) is the error code. The error message is "value of type 'PoseDetector' has no member 'process'".We can see 'process' method has been defined in 'PoseDetector' class:

NS_SWIFT_NAME(PoseDetector)@interface MLKPoseDetector : NSObject...- (void)processImage:(id<MLKCompatibleImage>)image          completion:(MLKPoseDetectionCallback)completion NS_SWIFT_NAME(process(_:completion:));@end

The problem is very strange, if I Write these codes in MLKitPlugin.m using Objective-C, it is built successfully. Also if I write a swift origin project(not flutter plugin), it is also built successfully. So is this problem related with Flutter? is this a project problem. Do I missed something?
Addition, 'Podfile' in main project:

# Uncomment this line to define a global platform for your project# platform :ios, '9.0'# CocoaPods analytics sends network stats synchronously affecting flutter build latency.ENV['COCOAPODS_DISABLE_STATS'] = 'true'project 'Runner', {'Debug' => :debug,'Profile' => :release,'Release' => :release,}def flutter_root  generated_xcode_build_settings_path = File.expand_path(File.join('..', 'Flutter', 'Generated.xcconfig'), __FILE__)  unless File.exist?(generated_xcode_build_settings_path)    raise "#{generated_xcode_build_settings_path} must exist. If you're running pod install manually, make sure flutter pub get is executed first"  end  File.foreach(generated_xcode_build_settings_path) do |line|    matches = line.match(/FLUTTER_ROOT\=(.*)/)    return matches[1].strip if matches  end  raise "FLUTTER_ROOT not found in #{generated_xcode_build_settings_path}. Try deleting Generated.xcconfig, then run flutter pub get"endrequire File.expand_path(File.join('packages', 'flutter_tools', 'bin', 'podhelper'), flutter_root)flutter_ios_podfile_setuptarget 'Runner' do  use_frameworks!  use_modular_headers!  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))endpost_install do |installer|  installer.pods_project.targets.each do |target|    flutter_additional_ios_build_settings(target)  endend