AVCaptureMetadataOutput的metadataObjectTypes属性的常量吗? [英] Constants for AVCaptureMetadataOutput's metadataObjectTypes property?

问题描述

使用AVFoundation检测图像中的特征(例如人脸或条形码)时，您必须拨打以下行:

When using AVFoundation to detect features (e.g. faces or barcodes) in an image, you must call a line such as:

AVCaptureMetadataOutput *metadataOutput = ...;
metadataOutput.metadataObjectTypes = metadataOutput.availableMetadataObjectTypes;

检查availableMetadataObjectTypes显示以下字符串:

Examining availableMetadataObjectTypes shows the following strings:

face,
"org.gs1.UPC-E",
"org.iso.Code39",
"org.iso.Code39Mod43",
"org.gs1.EAN-13",
"org.gs1.EAN-8",
"com.intermec.Code93",
"org.iso.Code128",
"org.iso.PDF417",
"org.iso.QRCode",
"org.iso.Aztec"

如果我正在编写条形码扫描应用程序，那么我不希望框架查找人脸，因此，我不想传递metadataOutput.availableMetadataObjectTypes，而是传递特定的条形码来查找.我希望不使用这些硬编码的字符串，而是希望将它们定义为某个地方的常量.

If I am writing a barcode scanning app, I don't want the framework to be looking for faces, so instead of passing metadataOutput.availableMetadataObjectTypes, I want to pass specific barcodes to look for. Rather than using these hard-coded strings, I was hoping they were defined as constants somewhere.

它们是否存在于框架中的任何位置，还是必须使用硬编码的字符串?

Do they exist anywhere in the framework, or must I use hard-coded strings?

推荐答案

只有AVMetadataMachineReadableCodeObject类(因此您可以执行以下操作:

So you can do something like this:

metadataOutput.metadataObjectType = @[AVMetadataObjectTypeQRCode, AVMetadataObjectTypeEAN13Code];

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