AVCaptureVideo不显示标签 | AVCaptureVideo不显示标签

本文介绍了AVCaptureVideo不显示标签的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在尝试从控制台保留对象，以将其显示为标签(classifierText).出现警告"UILabel.text必须仅从主线程使用".为什么将这些商品显示为标签，这似乎有什么问题?

I am trying to retain the objects from the console to be shown in as a label(classifierText). The warning of "UILabel.text must be used from main thread only" appears. What seems to the problem as to why the items are being shown as the label?

var previewLayer: AVCaptureVideoPreviewLayer!

let classifierText: UILabel = {
    let classifier = UILabel()
    classifier.translatesAutoresizingMaskIntoConstraints = false
    classifier.textColor = .black
    classifier.font = UIFont(name: "Times-New-Roman", size: 10)
    classifier.textAlignment = .center
    return classifier
}()

func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
    guard let pixelBuffer: CVPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return }
    guard let model =  try? VNCoreMLModel(for: Resnet50().model) else { return }
    let request = VNCoreMLRequest(model: model) { (finishedReq, err) in
    let results = finishedReq.results as?  [VNClassificationObservation]
    let firstObservation = results!.first
    self.classifierText.text = "\(firstObservation!.identifier as String)"

推荐答案

方法captureOutput(sampleBuffer, etc)不在主线程上运行.因此，您正在尝试从不是主线程的线程更改标签.

The method captureOutput(sampleBuffer, etc) does not run on the main thread. So you're trying to change the label from a thread that is not the main thread.

解决方案是将工作安排在主线程上，如下所示:

The solution is to schedule the work on the main thread, like so:

DispatchQueue.main.async {
    self.classifierText.text = "\(firstObservation!.identifier as String)"
}

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