在原生ios项目中集成flutter

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jzoom
    阅读 14 分钟
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    概述

    本文不想写一个全篇步骤式的文章来描写怎么集成flutter，而是期望用一种探索的方式来追寻答案。

    原理分析

    我们首先看下flutter项目和一般原生项目的大概区别。

    为了跳转方便，原生项目的入口一般是UINavigationController。

    而我们看下flutter默认给我们创建的模板为：

    clipboard.png

    clipboard.png

    这里我们来看下flutter的引擎源码，看下这段代码做了什么工作，源码路径为:https://github.com/flutter/en...

    我们首先看下`FlutterAppDelegate

    https://github.com/flutter/en...

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

....

- (BOOL)application:(UIApplication*)application
    willFinishLaunchingWithOptions:(NSDictionary*)launchOptions {
  return [_lifeCycleDelegate application:application willFinishLaunchingWithOptions:launchOptions];
}
....

    所以这里可以看到，FlutterAppDelegate完全是调用了FlutterPluginAppLifeCycleDelegate的所有方法。假设你的项目原先就有一个AppDelegate的实现类，那么可以参考FlutterAppDelegate的源码，创建一个FlutterPluginAppLifeCycleDelegate,并在所有方法中调用这个类实例的方法。

    原生项目中创建根ViewControler的方式可以使用StoryBoard，也可以使用代码创建。而flutter模板给我们创建的项目为StoryBoard的方式

    clipboard.png

    clipboard.png

    从这里我们可以发现，flutter默认项目模板是将FlutterViewController作为根ViewController。

    项目实战

    创建项目

    原理分析完毕，我们可以创建一个工程项目了.

    我们这里选择创建一个最常见的SingleViewApp

    clipboard.png

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    改成不使用StoryBoard，而是代码创建根ViewController

    clipboard.png

    为了演示方便，我们创建一个controller
    clipboard.png

    修改一下启动代码:

    
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];
    UIViewController* main = [[MainViewController alloc]initWithNibName:@"MainViewController" bundle:nil];
    UINavigationController* root = [[UINavigationController alloc]initWithRootViewController:main];
    self.window.backgroundColor = [UIColor whiteColor];
    self.window.rootViewController = root;
    [self.window makeKeyAndVisible];
    return YES;
}

    在MainViewController中，我们摆上两个按钮:

    clipboard.png

    创建flutter模块

    我们使用flutter自带命令创建一个flutter模块项目

    flutter create -t module my_flutter

    把创建出来的所有文件一起拷贝到上面ios原生项目的同一级目录中:

    clipboard.png

    使用pod初始化一下项目:

    cd myproject
pod init

    这样就生成了Podfile

    clipboard.png

    我们打开修改一下，以便将flutter包括在里面

    

platform :ios, '9.0'
target 'myproject' do

end

#新添加的代码
flutter_application_path = '../'
eval(File.read(File.join(flutter_application_path, '.ios', 'Flutter', 'podhelper.rb')), binding)

    运行下pod安装

    pod install

    clipboard.png

    我们可以看到，与刚才相比，新增加了workspace文件，我们关掉原来的项目，并打开workspace

    clipboard.png

    然后我们可以看到项目结构如下:

    clipboard.png

    编译一下:

    ld: '/Users/jzoom/SourceCode/myproject/myproject/DerivedData/myproject/Build/Products/Debug-iphoneos/FlutterPluginRegistrant/libFlutterPluginRegistrant.a(GeneratedPluginRegistrant.o)' does not contain bitcode. You must rebuild it with bitcode enabled (Xcode setting ENABLE_BITCODE), obtain an updated library from the vendor, or disable bitcode for this target. file '/Users/jzoom/SourceCode/myproject/myproject/DerivedData/myproject/Build/Products/Debug-iphoneos/FlutterPluginRegistrant/libFlutterPluginRegistrant.a' for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

    出现了这个错误

    打开项目编译配置，并搜索bit,出现下面结果:

    clipboard.png

    修改下Enable Bitcode为No

    clipboard.png

    此时编译ok。

    至此，在原生项目中配置flutter完毕，我们开始开发功能。

    修改AppDelegate

    由于我们的AppDelegate不是FlutterAppDelegate，所以我们按照前面分析的路子，改成如下:

    //
//  AppDelegate.m
//  myproject
//
//  Created by JZoom on 2019/4/9.
//  Copyright © 2019 JZoom. All rights reserved.
//

#import "AppDelegate.h"
#import "GeneratedPluginRegistrant.h"
#import <Flutter/Flutter.h>
#import "MainViewController.h"


@interface AppDelegate()<FlutterPluginRegistry>

@end

@implementation AppDelegate{
    FlutterPluginAppLifeCycleDelegate* _lifeCycleDelegate;
}


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];
    UIViewController* main = [[MainViewController alloc]initWithNibName:@"MainViewController" bundle:nil];
    UINavigationController* root = [[UINavigationController alloc]initWithRootViewController:main];
    self.window.backgroundColor = [UIColor whiteColor];
    self.window.rootViewController = root;
    [self.window makeKeyAndVisible];
    
    [GeneratedPluginRegistrant registerWithRegistry:self];
   return [_lifeCycleDelegate application:application didFinishLaunchingWithOptions:launchOptions];
}




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

- (void)dealloc {
    _lifeCycleDelegate = nil;
}

- (BOOL)application:(UIApplication*)application
willFinishLaunchingWithOptions:(NSDictionary*)launchOptions {
    return [_lifeCycleDelegate application:application willFinishLaunchingWithOptions: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];
}

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
- (void)application:(UIApplication*)application
didRegisterUserNotificationSettings:(UIUserNotificationSettings*)notificationSettings {
    [_lifeCycleDelegate application:application
didRegisterUserNotificationSettings:notificationSettings];
}
#pragma GCC diagnostic pop

- (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];
}

- (void)application:(UIApplication*)application
didReceiveLocalNotification:(UILocalNotification*)notification {
    [_lifeCycleDelegate application:application didReceiveLocalNotification:notification];
}

- (void)userNotificationCenter:(UNUserNotificationCenter*)center
       willPresentNotification:(UNNotification*)notification
         withCompletionHandler:
(void (^)(UNNotificationPresentationOptions options))completionHandler
API_AVAILABLE(ios(10)) {
    if (@available(iOS 10.0, *)) {
        [_lifeCycleDelegate userNotificationCenter:center
                           willPresentNotification:notification
                             withCompletionHandler: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 (^)())completionHandler {
    [_lifeCycleDelegate application:application
handleEventsForBackgroundURLSession:identifier
                  completionHandler:completionHandler];
}

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

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 120000
- (BOOL)application:(UIApplication*)application
continueUserActivity:(NSUserActivity*)userActivity
 restorationHandler:(void (^)(NSArray<id<UIUserActivityRestoring>>* __nullable
                              restorableObjects))restorationHandler {
#else
    - (BOOL)application:(UIApplication*)application
continueUserActivity:(NSUserActivity*)userActivity
restorationHandler:(void (^)(NSArray* __nullable restorableObjects))restorationHandler {
#endif
    return [_lifeCycleDelegate application:application
                      continueUserActivity:userActivity
                        restorationHandler:restorationHandler];
}
    
#pragma mark - FlutterPluginRegistry methods. All delegating to the rootViewController
    
- (NSObject<FlutterPluginRegistrar>*)registrarForPlugin:(NSString*)pluginKey {
    UIViewController* rootViewController = _window.rootViewController;
    if ([rootViewController isKindOfClass:[FlutterViewController class]]) {
        return
        [[(FlutterViewController*)rootViewController pluginRegistry] registrarForPlugin:pluginKey];
    }
    return nil;
}

- (BOOL)hasPlugin:(NSString*)pluginKey {
    UIViewController* rootViewController = _window.rootViewController;
    if ([rootViewController isKindOfClass:[FlutterViewController class]]) {
        return [[(FlutterViewController*)rootViewController pluginRegistry] hasPlugin:pluginKey];
    }
    return false;
}

- (NSObject*)valuePublishedByPlugin:(NSString*)pluginKey {
    UIViewController* rootViewController = _window.rootViewController;
    if ([rootViewController isKindOfClass:[FlutterViewController class]]) {
        return [[(FlutterViewController*)rootViewController pluginRegistry]
                valuePublishedByPlugin:pluginKey];
    }
    return nil;
}

#pragma mark - FlutterAppLifeCycleProvider methods

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

    创建FlutterViewController

    编辑下MainViewController

    - (IBAction)launchFlutter1:(id)sender {
    
    FlutterViewController* c = [[FlutterViewController alloc]init];
    [self.navigationController pushViewController:c animated:YES];
    
}

    编译下,运行点击按钮调取flutter视图，发现一片空白，并出现如下错误：

    2019-04-09 13:18:18.500285+0800 myproject[57815:1968395] [VERBOSE-1:callback_cache.cc(132)] Could not parse callback cache, aborting restore
2019-04-09 13:18:36.554643+0800 myproject[57815:1968395] Failed to find assets path for "Frameworks/App.framework/flutter_assets"
2019-04-09 13:18:36.658247+0800 myproject[57815:1969776] [VERBOSE-2:engine.cc(116)] Engine run configuration was invalid.
2019-04-09 13:18:36.659545+0800 myproject[57815:1969776] [VERBOSE-2:FlutterEngine.mm(294)] Could not launch engine with configuration.
2019-04-09 13:18:36.816199+0800 myproject[57815:1969793] flutter: Observatory listening on http://127.0.0.1:50167/

    我们看看和flutter自己创建的项目比，还差了什么

    clipboard.png

    如图：有三个地方,我们把这些文件copy一份放到我们的项目中,并且设置一下编译选项:

    clipboard.png

    修改下项目的配置，增加一个脚本

    clipboard.png

    /bin/sh "$FLUTTER_ROOT/packages/flutter_tools/bin/xcode_backend.sh" thin

    clipboard.png

    放到Copy Bundle Resources下面

    结果：

    clipboard.png

    进行优化

    在上面的步骤里面，我们通过直接文件拷贝将.ios目录下的flutter生成文件拷贝到了原生项目里面，显然我们不能每一次都手动这么做，我们可以添加一个命令来做这件事。

    rm -rf ${SOURCE_ROOT}/Flutter/Generated.xcconfig
cp -ri ../.ios/Flutter/Generated.xcconfig ${SOURCE_ROOT}/Flutter/Generated.xcconfig
rm -rf ${SOURCE_ROOT}/Flutter/App.framework
cp -ri ../.ios/Flutter/App.framework ${SOURCE_ROOT}/Flutter/App.framework

    我们把这个命令放到前面去
    clipboard.png

    问题

    Q : 如何调用flutter的不同页面?

    A : 我们首先定义一下路由

    clipboard.png

    然后我们可以这么调用

     /// flutter的路由视图
    FlutterViewController* c = [[FlutterViewController alloc]init];
    [c setInitialRoute:@"page2"];
    [self.navigationController pushViewController:c animated:YES];

    Q : 如何在原生项目中调试flutter?
    A : 首先在命令行启动flutter的监听

    flutter attach

    如果有多台设备，需要选择一下设备

    flutter attach -d 设备标志

    然后就可以在xcode中启动调试运行项目

    clipboard.png

    改动代码之后按下键盘上面的r键就可以了。

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    jzoom
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