前言

Flutter 是一個頗有潛力的框架，可是目前使用Flutter的APP並不算不少，相關資料並不豐富，介紹現有工程引入Flutter的相關文章也比較少。項目從零開始，引入Flutter操做比較簡單，可是現有工程引入Flutter 須要費不少精力和時間，這裏是我在完成現有iOS工程引入Flutter後寫的一次總結文章。ios

Flutter 環境搭建

首先是要搭建Flutter環境，以前也寫了一篇相關文章搭建Flutter-iOS開發環境，能夠參考一下能夠去官網查看：github.com/flutter/flu… 比較簡單，這裏不作贅述。git

現有iOS工程引入Flutter

1、創建Flutter module

首先創建flutter module，主要是用於獲取改flutter app中的Generated.xcconfig和frameworkgithub

cd some/path/
$ flutter create -t module my_flutter
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也能夠用xcode

flutter create app
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創建flutter app，flutter app中也有Generated.xcconfig和frameworkbash

2、新建配置文件

根據官網，須要在工程中創建三個配置文件： Flutter.xcconfig 、Debug.xcconfig、Release.xcconfig 在XCode工程對應目錄，右擊，選擇新建文件（New File），選中建立xcconfig文件，如圖： markdown

在`Flutter.xcconfig`中填寫：

//這裏填寫前面創建的flutter module 的Generated.xcconfig的路徑
#include "../../my_flutter/.ios/Flutter/Generated.xcconfig"
ENABLE_BITCODE=NO
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在 `Debug.xcconfig`中填寫:

#include "../Flutter/Flutter.xcconfig"

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在 Release.xcconfig中填寫:app

#include "../Flutter/Flutter.xcconfig"
FLUTTER_BUILD_MODE=release
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若是工程中用cocoapods管理，須要在 Debug.xcconfig和Release.xcconfig添加pod的路徑：框架

例如 Release.xcconfig中ide

#include "Flutter.xcconfig"
#include "工程路徑/Pods/Target Support Files/******.release.xcconfig"//pod路徑
FLUTTER_BUILD_MODE=release
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在準備好這些xcconfig文件後，須要到XCode工程PROJECT（注意是PROJECT,不是Target）中的Configuration選項裏，將對應的target選擇成前面的xcconfig文件，Debug用Debug.xcconfig, Release用 Release.xcconfigoop

注意：進行Archive打包的時候，不管是Debug包仍是Release包，須要切換到Release.xcconfig，否則會報錯。

3、爲編譯Dart引入相關build phase

在工程的Build Phase中新建一個Run Script,用於編譯時運行腳本，創建方法如圖：

創建Run Script後，須要移動其對應的位置，須要在Target dependencies以後，若是用cocoapods管理工程須要在，Check Pods Manifest.lock以後：

在腳本框中，填入如下代碼，用於引進Flutter中的xcode_backend腳本：

"$FLUTTER_ROOT/packages/flutter_tools/bin/xcode_backend.sh" build
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如圖：

4、生成和添加Framework

完成前面的配置後，即可以在XCode對工程進行編譯build (Command+B)，在提示「 Build Success 」後，在iOS工程文件夾中會生成一個Flutter文件夾，將其加入工程目錄中,建議和剛纔xcconfig所在目錄並列，

右鍵項目目錄，選擇 Add Files to 'xxx' ，Options選Create groups，添加編譯生成的Flutter文件夾。須要注意可是：Flutter目錄下有個flutter_assets文件，不能使用Create groups的方式添加，只能用Creat folder references的Options，不然Flutter頁面會空白渲染不出來。能夠刪了flutter_assets在用Creat folder references從新添加。

在添加完Flutter 文件夾以後，去Embeded Binaries中添加App.framework和Flutter.framework

5、AppDelegate改造

Flutter須要和APP進行交互，須要對AppDelegate 進行改造：

AppDelegate.h文件中：

#import <Flutter/Flutter.h>

@interface AppDelegate : FlutterAppDelegate <UIApplicationDelegate, FlutterAppLifeCycleProvider>

@end
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AppDelegate.m 文件中：

#import "AppDelegate.h"

@interface AppDelegate ()
    
@end

@implementation AppDelegate
{
  FlutterPluginAppLifeCycleDelegate *_lifeCycleDelegate;
}
    
- (instancetype)init {
    if (self = [super init]) {
        _lifeCycleDelegate = [[FlutterPluginAppLifeCycleDelegate alloc] init];
    }
    return self;
}
    
- (BOOL)application:(UIApplication*)application
didFinishLaunchingWithOptions:(NSDictionary*)launchOptions {
    return [_lifeCycleDelegate application:application didFinishLaunchingWithOptions:launchOptions];
}
    
- (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];
}

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6、新建FlutterViewController

主要配置基本上已經完成，只要在main.dart實現Flutter的業務代碼便可

在原有工程中，創建FlutterViewController來承載 main.dart實現的Flutter頁面，如：

self.flutterViewController = [[FlutterViewController alloc] initWithProject:nil nibName:nil bundle:nil];
    [self.navigationController pushViewController:self.flutterViewController animated:YES];
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後語

到這裏現有iOS工程引入Flutter的工做就完成了，一些細節上的修改須要根據場景進行修改，例如Flutter和Native的數據通訊等。

Flutter-現有iOS工程引入Flutter

前言