[英]Flutter pass Uint8List to iOS Objective-c
I am trying to pass an image as Uint8List to native code Android/iOS from Flutter, but getting an error in iOS side.我正在尝试将图像作为 Uint8List 从 Flutter 传递给本机代码 Android/iOS,但在 iOS 端出现错误。 I am modifying a plugin and i never developed in iOS before.我正在修改一个插件,我之前从未在 iOS 中开发过。 Here is the Flutter code to capture an image from widget and send the Uint8List to native code.这是 Flutter 代码,用于从小部件捕获图像并将 Uint8List 发送到本机代码。
Future<void> _capturePng() async {
RenderRepaintBoundary boundary =
globalKey.currentContext.findRenderObject();
ui.Image image = await boundary.toImage(pixelRatio: 1.50);
ByteData byteData = await image.toByteData(format: ui.ImageByteFormat.png);
Uint8List pngBytes = byteData.buffer.asUint8List();
printer.printImage(pngBytes);
}
In Android, i am using Kotlin:在 Android 中,我使用的是 Kotlin:
private fun printImage(call: MethodCall, result: Result) {
val image = call.arguments as ByteArray
val res = mPrinterPlugin.printImage(image)
result.success(res)
}
In iOS, the plugin is written in Objective-C.在iOS中,插件写在Objective-C中。 i added this check for my image我为我的图片添加了此检查
else if([@"imagePrint" isEqualToString:call.method]){
NSData *imgBytes = call.arguments;
UIImage *label = [UIImage imageWithData:imgBytes];
}
I saw that Uint8List
is FlutterStandardTypedData typedDataWithBytes
in iOS, but when i set the imgBytes type to it i get an error.我在 iOS 中看到Uint8List
是FlutterStandardTypedData typedDataWithBytes
typedDataWithBytes,但是当我将 imgBytes 类型设置为它时出现错误。
You should take first argument as a typed data, probably:您应该将第一个参数作为类型数据,可能是:
NSArray *args = call.arguments;
FlutterStandardTypedData *list = args[0];
kotlin: kotlin:
val args: List<Any> = call.arguments as List<Any>
val list = args[0] as ByteArray
and you invoke it like this:你像这样调用它:
Uint8List uint8List;
_channel.invokeMethod("your_function_name", [uint8List]);
I just dealt with this.我刚刚处理了这个。 Letting Xcode
do its magical conversion was burning me.让Xcode
做它的神奇转换让我很着急。 For instance, in your iOS plugin implementation, the line:例如,在您的 iOS 插件实现中,该行:
NSData *imgBytes = call.arguments;
When i was doing this, in Xcode
the debugger would see the data type would come through as a FlutterStandardTypedData
(as i passed in a list of ints) but every time i would try to access an element/object it would give me memory errors.当我这样做时,在Xcode
中,调试器会看到数据类型将以FlutterStandardTypedData
的形式出现(因为我传入了一个整数列表),但每次我尝试访问一个元素/对象时,它都会给我 memory 错误。 It was like Xcode
was honoring my parameter list ( NSArray
) in reality, but showing me the data type as a FlutterStandardTypedData
while debugging.就像Xcode
在现实中尊重我的参数列表( NSArray
),但在调试时向我显示数据类型为FlutterStandardTypedData
。 Seemed like a bug in the IDE
to be honest.老实说,这似乎是IDE
中的一个错误。
Just as the upvoted answer shows, i resolved by using the flutter data type:正如赞成的答案所示,我通过使用 flutter 数据类型解决了问题:
FlutterStandardTypedData *bytesList = call.arguments[@"listOfBytes"];
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