iOS：

- (NSData *)tj_imageNamed:(NSString *)imageName
{
    UIImage *image = nil;
    if (image == nil) {
        image = [UIImage imageNamed:imageName];
        if(!image){
            image = [[UIImage imageWithContentsOfFile:[[self tj_refreshBundle] pathForResource:imageName ofType:@"png"]] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
        }
        if(!image){
            image = [[UIImage imageWithContentsOfFile:[[self tj_refreshBundle] pathForResource:[NSString stringWithFormat:@"%@@%dx",imageName,(int)[[UIScreen mainScreen]scale]] ofType:@"png"]] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
        }
    }
    return UIImagePNGRepresentation(image);;
}
- (NSBundle *)tj_refreshBundle
{
    static NSBundle *refreshBundle = nil;
    if (refreshBundle == nil) {
        NSBundle *currentBundle = [NSBundle bundleForClass:[self class]];
        refreshBundle = [NSBundle bundleWithPath:[currentBundle pathForResource:@"selfBundleName" ofType:@"bundle"]];
        if(!refreshBundle){
            refreshBundle = [NSBundle mainBundle];
        }
    }
    return refreshBundle;
}

Android:

public Bitmap tj_imageName(String imageName) {
  ApplicationInfo appInfo = BaseLibKit.getContext().getApplicationInfo();
  int resID = BaseLibKit.getContext().getResources().getIdentifier(imageName, "drawable", appInfo.packageName);
  Bitmap imageBitmap =   
  BitmapFactory.decodeResource(BaseLibKit.getContext().getResources(), resID);
        return imageBitmap;
}

public byte[] getBitmapByte(Bitmap bitmap) {
  ByteArrayOutputStream out = new ByteArrayOutputStream();
  bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
    try {
        out.flush();
        out.close();
        } catch (IOException e) {
            e.printStackTrace();
    }
        return out.toByteArray();
  }

如果 bitmap.compress第一个参数为 Bitmap.CompressFormat.JPG 要注意图片资源是否有透明通道，如果有，透明通道会默认为黑色

• 以上是原生部分代码，根据图片名称获取图片二进制，通过BasicMessageChannel 发送给Flutter,然后解析。
• 或者Fultter 部分发送获取图片通信消息，由原生回调回去。
  使用 Uint8List? 类型接收
  举例
  Uint8List? _audio_icon_pause;

展示在组件上就是

child: (_audio_state_icon != null? 
Image.memory(_audio_state_icon! ):
Image.network("defaultIcon")),

iOS 获取Flutter 资源图片

NSString* key = [registrar lookupKeyForAsset:@"assetsPath/imageName"];
NSString* path = [[NSBundle mainBundle] pathForResource:key ofType:nil];

Android 获取Flutter 资源图片

AssetManager assetManager = registrar.context().getAssets();
String key = registrar.lookupKeyForAsset("assetsPath/imageName");
AssetFileDescriptor fd = assetManager.openFd(key);