现有iOS工程添加Futter模块

首先要安装flutter环境，参考：Flutter 环境搭建（Mac）
虽然能混合但还不支持用Xcode直接开发，可以用VSCode。

1. 创建flutter模块
   cd到项目根目录
   执行命令 flutter create -t module my_flutter

2. podfile添加依赖
   添加：

flutter_application_path = '../my_flutter'
eval(File.read(File.join(flutter_application_path, '.ios', 'Flutter', 'podhelper.rb')), binding)
'../my_flutter' 

flutter_application_path 路径是 1 生成的文件夹
保存
安装 pod install 将Flutter模块作为依赖添加到主项目

3.配置build phase，为编译Dart 代码添加编译选项
xcode->build phase->如果没有点➕号->New Run Script Phase
添加脚本

"$FLUTTER_ROOT/packages/flutter_tools/bin/xcode_backend.sh" build
"$FLUTTER_ROOT/packages/flutter_tools/bin/xcode_backend.sh" embed 

编译如果报bitcode错误，关闭bitcode，目前flutter不支持。

4. AppDelegate设置
   方法一：
   添加头文件

#import <Flutter/Flutter.h>
#import <FlutterPluginRegistrant/GeneratedPluginRegistrant.h> 

flutter协议 FlutterAppLifeCycleProvider

@interface AppDelegate : UIResponder <UIApplicationDelegate, FlutterAppLifeCycleProvider>

添加FlutterPluginAppLifeCycleDelegate的生命周期

@implementation AppDelegate
{
    FlutterPluginAppLifeCycleDelegate *_lifeCycleDelegate;
}

- (instancetype)init {
    if (self = [super init]) {
        _lifeCycleDelegate = [[FlutterPluginAppLifeCycleDelegate alloc] init];
    }
    return self;
}

- (BOOL)application:(UIApplication*)application
didFinishLaunchingWithOptions:(NSDictionary*)launchOptions {
    [GeneratedPluginRegistrant registerWithRegistry:self]; // Only if you are using Flutter plugins.
    return [_lifeCycleDelegate application:application didFinishLaunchingWithOptions:launchOptions];
}

// Returns the key window's rootViewController, if it's a FlutterViewController.
// Otherwise, returns nil.
- (FlutterViewController*)rootFlutterViewController {
    UIViewController* viewController = [UIApplication sharedApplication].keyWindow.rootViewController;
    if ([viewController isKindOfClass:[FlutterViewController class]]) {
        return (FlutterViewController*)viewController;
    }
    return nil;
}

- (void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
    [super touchesBegan:touches withEvent:event];

    // Pass status bar taps to key window Flutter rootViewController.
    if (self.rootFlutterViewController != nil) {
        [self.rootFlutterViewController handleStatusBarTouches:event];
    }
}

- (void)applicationDidEnterBackground:(UIApplication*)application {
    [_lifeCycleDelegate applicationDidEnterBackground:application];
}

- (void)applicationWillEnterForeground:(UIApplication*)application {
    [_lifeCycleDelegate applicationWillEnterForeground:application];
}

- (void)applicationWillResignActive:(UIApplication*)application {
    [_lifeCycleDelegate applicationWillResignActive:application];
}

- (void)applicationDidBecomeActive:(UIApplication*)application {
    [_lifeCycleDelegate applicationDidBecomeActive:application];
}

- (void)applicationWillTerminate:(UIApplication*)application {
    [_lifeCycleDelegate applicationWillTerminate:application];
}

- (void)application:(UIApplication*)application
didRegisterUserNotificationSettings:(UIUserNotificationSettings*)notificationSettings {
    [_lifeCycleDelegate application:application
didRegisterUserNotificationSettings:notificationSettings];
}

- (void)application:(UIApplication*)application
didRegisterForRemoteNotificationsWithDeviceToken:(NSData*)deviceToken {
    [_lifeCycleDelegate application:application
didRegisterForRemoteNotificationsWithDeviceToken:deviceToken];
}

- (void)application:(UIApplication*)application
didReceiveRemoteNotification:(NSDictionary*)userInfo
fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result))completionHandler {
    [_lifeCycleDelegate application:application
       didReceiveRemoteNotification:userInfo
             fetchCompletionHandler:completionHandler];
}

- (BOOL)application:(UIApplication*)application
            openURL:(NSURL*)url
            options:(NSDictionary<UIApplicationOpenURLOptionsKey, id>*)options {
    return [_lifeCycleDelegate application:application openURL:url options:options];
}

- (BOOL)application:(UIApplication*)application handleOpenURL:(NSURL*)url {
    return [_lifeCycleDelegate application:application handleOpenURL:url];
}

- (BOOL)application:(UIApplication*)application
            openURL:(NSURL*)url
  sourceApplication:(NSString*)sourceApplication
         annotation:(id)annotation {
    return [_lifeCycleDelegate application:application
                                   openURL:url
                         sourceApplication:sourceApplication
                                annotation:annotation];
}

- (void)application:(UIApplication*)application
performActionForShortcutItem:(UIApplicationShortcutItem*)shortcutItem
  completionHandler:(void (^)(BOOL succeeded))completionHandler NS_AVAILABLE_IOS(9_0) {
    [_lifeCycleDelegate application:application
       performActionForShortcutItem:shortcutItem
                  completionHandler:completionHandler];
}

- (void)application:(UIApplication*)application
handleEventsForBackgroundURLSession:(nonnull NSString*)identifier
  completionHandler:(nonnull void (^)(void))completionHandler {
    [_lifeCycleDelegate application:application
handleEventsForBackgroundURLSession:identifier
                  completionHandler:completionHandler];
}

- (void)application:(UIApplication*)application
performFetchWithCompletionHandler:(void (^)(UIBackgroundFetchResult result))completionHandler {
    [_lifeCycleDelegate application:application performFetchWithCompletionHandler:completionHandler];
}

- (void)addApplicationLifeCycleDelegate:(NSObject<FlutterPlugin>*)delegate {
    [_lifeCycleDelegate addDelegate:delegate];
}
@end

方法二：
也可以修改 AppDelegate 继承自 FlutterAppDelegate

#import <Flutter/Flutter.h>

@interface AppDelegate : FlutterAppDelegate
@end

修改AppDelegate.m文件：

#import <FlutterPluginRegistrant/GeneratedPluginRegistrant.h> 

#include "AppDelegate.h"

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  [GeneratedPluginRegistrant registerWithRegistry:self];
  return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

@end

5.简单使用 FlutterViewController

跳转到一个flutter的VC:

#import <Flutter/Flutter.h>
#import "ViewController.h"

@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
     FlutterViewController* flutterVC = [[FlutterViewController alloc] init];
    [self presentViewController:flutterVC animated:YES completion:nil];
}

设置路由跳转的别的组件上:

[flutterVC setInitialRoute:@"xxxx"];

Flutter的程序入口：你的flutter模块目录/lib/main.dart，Flutter开发使用的语言是dart，百度百科：

Dart是面向对象的、类定义的、单继承的语言。它的语法类似C语言，可以转译为JavaScript，支持接口(interfaces)、混入(mixins)、抽象类(abstract classes)、具体化泛型(reified generics)、可选类型(optional typing)和sound type system ^[3] 。