Flutter - 原生交互 - 相机Camera - 01

最新推荐文章于 2025-07-30 21:27:12 发布

原创

最新推荐文章于 2025-07-30 21:27:12 发布 · 2.3k 阅读

19 ·

CC 4.0 BY-SA版权

文章标签：

#Flutter #Dart #iOS

环境

Flutter 3.29

macOS Sequoia 15.4.1

Xcode 16.3

集成

Flutter提供了camera插件来拍照和录视频，它提供了一系列可用的相机，并使用特定的相机展示相机预览、拍照、录视频。

添加依赖

camera: 提供使用设备相机模块的工具
path_provider: 寻找存储图片的正确路径
path: 创建适配任何平台的路径

flutter pub add camera path_provider path

执行完成后iOS工程的GeneratedPluginRegistrant.m文件会自动生成对应的集成代码

#if __has_include(<camera_avfoundation/CameraPlugin.h>)
#import <camera_avfoundation/CameraPlugin.h>
#else
@import camera_avfoundation;
#endif

#if __has_include(<path_provider_foundation/PathProviderPlugin.h>)
#import <path_provider_foundation/PathProviderPlugin.h>
#else
@import path_provider_foundation;
#endif
...

[CameraPlugin registerWithRegistrar:[registry registrarForPlugin:@"CameraPlugin"]];


[PathProviderPlugin registerWithRegistrar:[registry registrarForPlugin:@"PathProviderPlugin"]];

分析

[registry registrarForPlugin:@“CameraPlugin”]

在AppDelegate.swfit的application(_:didFinishLaunchingWithOptions:)中将FlutterAppDelegate的子类AppDelegate对象作为参数传入并调用该方法

GeneratedPluginRegistrant.register(with: self)

源码: FlutterAppDelegate.mm

- (NSObject<FlutterPluginRegistrar>*)registrarForPlugin:(NSString*)pluginKey {
   
   
  /// <1> 获取应用的flutterRootViewController对象
  FlutterViewController* flutterRootViewController = [self rootFlutterViewController];
  if (flutterRootViewController) {
   
   
    /// <4> 返回一个FlutterEngine对象
    return [[flutterRootViewController pluginRegistry] registrarForPlugin:pluginKey];
  }
  return nil;
}

// Returns the key window's rootViewController, if it's a FlutterViewController.
// Otherwise, returns nil.
- (FlutterViewController*)rootFlutterViewController {
   
   
  ///- (FlutterViewController*(^ rootFlutterViewControllerGetter) (void))
  /// <2> 检查是否有外部注入,有则使用自定义的回调获取FlutterViewController对象
  if (_rootFlutterViewControllerGetter != nil) {
   
   
    return _rootFlutterViewControllerGetter();
  }
  /// <3> 没有则检查window的rootViewController属性,如果是FlutterViewController则返回,否则返回nil
  UIViewController* rootViewController = _window.rootViewController;
  if ([rootViewController isKindOfClass:[FlutterViewController class]]) {
   
   
    return (FlutterViewController*)rootViewController;
  }
  return nil;
}

`[flutterRootViewController pluginRegistry]`

第<4>步中的方法调用在 FlutterViewController.mm

///  pluginRegistry方法获得一个遵守FlutterPluginRegistry协议的对象
- (id<FlutterPluginRegistry>)pluginRegistry {
   
   
    return self.engine;
}
...

/// engine是FlutterEngine对象
- (void)sharedSetupWithProject:(nullable FlutterDartProject*)project
                  initialRoute:(nullable NSString*)initialRoute {
   
   
...
engine = [[FlutterEngine alloc] initWithName:@"io.flutter"
                                         project:project
                          allowHeadlessExecution:self.engineAllowHeadlessExecution
                              restorationEnabled:self.restorationIdentifier != nil];
...
_engine = engine;
...              

- (instancetype)initWithEngine:(FlutterEngine*)engine
                       nibName:(nullable NSString*)nibName
                        bundle:(nullable NSBundle*)nibBundle {
   
   
...
_engine = engine;

FlutterPluginRegistry协议的继承结构

`FlutterEngine`对象调用`registrarForPlugin:`方法

源码: FlutterEngine.mm

/// 文件: FlutterEngine.mm
...
/**
 * All registrars returned from registrarForPlugin:
 */
@property(nonatomic, readonly)
    NSMutableDictionary<NSString*, FlutterEngineRegistrar*>* pluginRegistrars;
...

- (id<FlutterPluginRegistrar>)registrarForPlugin:(NSString*)pluginName {
   
   
  /// <5> 检查可变字典中是否已存在插件名的key
  id<FlutterPluginRegistrar> registrar = self.pluginRegistrars[pluginName];
  if (!registrar) {
   
   
    /// <6> 首次注册,生成FlutterEngineRegistrar对象并持有pluginName和弱引用FlutterEngine 对象

    /// 为什么是弱引用?
    /// 文件:FlutterViewController.m 强引入了FlutterEngine对象
    /// @property(nonatomic, readonly) FlutterEngine* engine;
    
    FlutterEngineRegistrar* registrarImpl =
        [[FlutterEngineRegistrar alloc] initWithPlu