为现有 iOS项目集成 Flutter

- (void)jumpToFlutter {
    FlutterViewController *viewController = [FlutterViewController new];
    [self.navigationController pushViewController:viewController animated:YES];
}

// AppDelegate 或者模块的 Delegate

@interface DemoFlutterBaseAppDelegate : NSObject <ModularApplicationDelegate, FlutterPluginRegistry>

/**
 FlutterBinaryMessenger
 this determines which view controller is the flutter view controller
 nomally, flutter view controller provides the binary messages
 @return root Flutter ViewController
 */
- (NSObject<FlutterBinaryMessenger> *)binaryMessenger;

/**
 FlutterTextureRegistry
 this determines which view controller is the flutter view controller
 nomally, flutter view controller provides the custom textures
 @return root Flutter ViewController
 */
- (NSObject<FlutterTextureRegistry> *)textures;

@end

// Registrar 声明和实现

@interface DemoFlutterAppDelegateRegistrar : NSObject<FlutterPluginRegistrar>

@property(nonatomic, copy) NSString *pluginKey;
@property(nonatomic, strong) DemoFlutterBaseAppDelegate *appDelegate;

- (instancetype)initWithPlugin:(NSString*)pluginKey appDelegate:(DemoFlutterBaseAppDelegate*)delegate;

@end

@implementation DemoFlutterAppDelegateRegistrar
- (instancetype)initWithPlugin:(NSString*)pluginKey appDelegate:(DemoFlutterBaseAppDelegate*)appDelegate {
    self = [super init];
    NSAssert(self, @"Super init cannot be nil");
    _pluginKey = [pluginKey copy];
    _appDelegate = appDelegate;
    return self;
}


- (NSObject<FlutterBinaryMessenger>*)messenger {
    return [_appDelegate binaryMessenger];
}

- (NSObject<FlutterTextureRegistry>*)textures {
    return [_appDelegate textures];
}

- (void)publish:(NSObject*)value {
    _appDelegate.pluginPublications[_pluginKey] = value;
}

- (void)addMethodCallDelegate:(NSObject<FlutterPlugin>*)delegate
                      channel:(FlutterMethodChannel*)channel {
    [channel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
        [delegate handleMethodCall:call result:result];
    }];
}

- (void)addApplicationDelegate:(NSObject<FlutterPlugin>*)delegate {
    [_appDelegate.pluginDelegates addObject:delegate];
}

- (NSString*)lookupKeyForAsset:(NSString*)asset {
    return [FlutterDartProject lookupKeyForAsset:asset];
}

- (NSString*)lookupKeyForAsset:(NSString*)asset fromPackage:(NSString*)package {
    return [FlutterDartProject lookupKeyForAsset:asset fromPackage:package];
}

@end


// AppDelegate实现

@interface DemoFlutterBaseAppDelegate ()

@property(nonatomic, strong) DemoFlutterBaseViewController *rootController;
@property(readonly, nonatomic) NSMutableArray* pluginDelegates;
@property(readonly, nonatomic) NSMutableDictionary* pluginPublications;

@end

@implementation DemoFlutterBaseAppDelegate

/*
 * ... 这里写转发各种声明周期事件给 plugin
 */
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    for (id<FlutterPlugin> plugin in _pluginDelegates) {
        if ([plugin respondsToSelector:_cmd]) {
            [plugin application:application didFinishLaunchingWithOptions:launchOptions];
        }
    }
    return YES;
}

#pragma mark - getters for flutter

// 返回 FlutterViewController实例
- (FlutterViewController *)rootController {
    // ...
}

- (NSObject<FlutterBinaryMessenger> *)binaryMessenger
{
    if ([self.rootController conformsToProtocol:@protocol(FlutterBinaryMessenger)]) {
        return (NSObject<FlutterBinaryMessenger> *)self.rootController;
    }
    return nil;
}

- (NSObject<FlutterTextureRegistry> *)textures
{
    if ([self.rootController conformsToProtocol:@protocol(FlutterTextureRegistry)]) {
        return (NSObject<FlutterTextureRegistry> *)self.rootController;
    }
    return nil;
}

- (NSObject<FlutterPluginRegistrar>*)registrarForPlugin:(NSString*)pluginKey {
    NSAssert(self.pluginPublications[pluginKey] == nil, @"Duplicate plugin key: %@", pluginKey);
    self.pluginPublications[pluginKey] = [NSNull null];
    return [[DemoFlutterAppDelegateRegistrar alloc] initWithPlugin:pluginKey appDelegate:self];
}

- (BOOL)hasPlugin:(NSString*)pluginKey {
    return _pluginPublications[pluginKey] != nil;
}

- (NSObject*)valuePublishedByPlugin:(NSString*)pluginKey {
    return _pluginPublications[pluginKey];
}

@end

flutter run --use-application-binary /path/to/Payload.zip