ios - 使用 View 中的相机对应用程序进行屏幕截图会返回空白图像

Question

我有这个代码来截取应用程序的屏幕截图:

    var imageSize = CGSize.zero

    let orientation = UIApplication.shared.statusBarOrientation
    if UIInterfaceOrientationIsPortrait(orientation) {
        imageSize = UIScreen.main.bounds.size
    } else {
        imageSize = CGSize(width: UIScreen.main.bounds.size.height, height: UIScreen.main.bounds.size.width)
    }

    UIGraphicsBeginImageContextWithOptions(imageSize, false, 0)
    for window in UIApplication.shared.windows {
        window.drawHierarchy(in: window.bounds, afterScreenUpdates: true)
    }

    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    self.captureImageView.image = image

这是我用于显示相机的代码:

    let captureDevice = AVCaptureDevice.default(for: AVMediaType.video)

    do {
        let input = try AVCaptureDeviceInput(device: captureDevice!)

        captureSession = AVCaptureSession()
        captureSession?.addInput(input)
    } catch {
        print(error)
    }

    videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession!)
    videoPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
    videoPreviewLayer?.frame = view.layer.bounds
    self.cameraView.layer.addSublayer(videoPreviewLayer!)

    let previewLayerConnection: AVCaptureConnection? = videoPreviewLayer?.connection
    if previewLayerConnection?.isVideoOrientationSupported != nil {
        previewLayerConnection?.videoOrientation = AVCaptureVideoOrientation.landscapeLeft
    }

    captureSession?.startRunning()

我已经尝试了其他 stackoverflow 用户关于这个问题的所有方法，但它并没有真正起作用。可能是什么原因以及如何解决？

Answer 1

for window in UIApplication.shared.windows {
    window.drawHierarchy(in: window.bounds, afterScreenUpdates: true)
}

此处您使用该窗口作为屏幕截图 View 。默认情况下，您的窗口颜色为黑色，这就是您获得黑色屏幕截图的原因。

使用 View Controller subview 之一。

尝试使用更新的代码获取第一个屏幕截图。然后用你的相机实现。

您的代码应如下所示

view.drawHierarchy(in: view.bounds, afterScreenUpdates: true)