Ios AVFoundation videoZoomFactor不工作（Swift）

除了zoomfactor，我想使用的所有相机调整都正常工作。我不明白为什么会这样……有什么想法吗？自定义曝光和焦点设置工作正常。iOS中有什么我不知道的变化吗

captureSession = AVCaptureSession()
    captureSession?.sessionPreset = AVCaptureSessionPresetPhoto
    stillImageOutput = AVCapturePhotoOutput()

    let device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)

    do{
        do{
            try device?.lockForConfiguration()
            device?.setFocusModeLockedWithLensPosition(focusValue, completionHandler: {(time) -> Void in})
            device?.setExposureModeCustomWithDuration(CMTimeMake(1, exposureValue), iso: ISOValue, completionHandler: {(time) -> Void in})
            let zoomFactor:CGFloat = 16
            device?.videoZoomFactor = zoomFactor
            device?.unlockForConfiguration()

        }catch{
            print(error)
        }

        stillImageOutput.isHighResolutionCaptureEnabled = true
        let input = try AVCaptureDeviceInput(device: device)
        if(captureSession.canAddInput(input)){
            captureSession.addInput(input)
            if(captureSession.canAddOutput(stillImageOutput)){
                captureSession.addOutput(stillImageOutput)

                captureSession.startRunning()
                let captureVideoLayer: AVCaptureVideoPreviewLayer = AVCaptureVideoPreviewLayer.init(session: captureSession)
                captureVideoLayer.frame = self.previewView.bounds
                captureVideoLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
                self.previewView.layer.insertSublayer(captureVideoLayer, at: 0)
            }
        }
    }catch{
        print(error)
    }

---

原来我只是在错误的地方设置了我的设备设置。如果将lockconfig try块移到捕获会话内容下方，它就会按预期工作。

使用苹果的照片和视频采集示例代码，即AVFoundation，我尝试在代码中更改iPhone摄像头的设备缩放

在的帮助下，我意识到放置缩放操作属性的代码位置很重要，而且，在操作任何视频设备之前，请确保使用device.lockForConfiguration！两者都是重要的代码位置和锁定

这里有一个链接和一个屏幕截图，可以看到下载按钮，原始的苹果示例可以从中获取：

以下是原始Apple示例的代码摘录，其中包含我的代码，用于操纵插入到正确位置的缩放：

Swift-4.2/Xcode 10.0，iOS 11.0 SDK

// Call this on the session queue.
private func configureSession() {
    if setupResult != .success {
        return
    }

    // ... missing original code (not important for this illustration)...

    // Add video input.
    do {
        var defaultVideoDevice: AVCaptureDevice?

        // ... missing original code (not important for this illustration)...

        if session.canAddInput(videoDeviceInput) {
            session.addInput(videoDeviceInput)
            self.videoDeviceInput = videoDeviceInput

            // ... missing original code (not important for this illustration)...

        } else {
            print("Could not add video device input to the session")
            setupResult = .configurationFailed
            session.commitConfiguration()
            return
        }

        // !!!!!!!!!!!!!!!! MY CODE THAT MANIPULATES THE ZOOM  !!!!!!!!!!!!!!!!!!!!!!!!!!!!
        // !!!!!!!!!!!!!!!! PLACE IT HERE AND ZOOM WILL WORK !!!!!!!!!!!!!!!!!!!!!!!!!!!!
        guard let device = defaultVideoDevice else { return }
        do {
            try device.lockForConfiguration()
            defer { device.unlockForConfiguration() }
            device.videoZoomFactor = 10.0
        } catch {
            debugPrint(error)
        }
        // !!!!!!!!!!!!!! END OF MY CODE THAT MANIPULATES THE ZOOM  !!!!!!!!!!!!!!!!!!!!!!!!!!

    } catch {
        print("Could not create video device input: \(error)")
        setupResult = .configurationFailed
        session.commitConfiguration()
        return
    }

    // Add audio input.
    do {
        let audioDevice = AVCaptureDevice.default(for: .audio)
        let audioDeviceInput = try AVCaptureDeviceInput(device: audioDevice!)

        if session.canAddInput(audioDeviceInput) {
            session.addInput(audioDeviceInput)
        } else {
            print("Could not add audio device input to the session")
        }
    } catch {
        print("Could not create audio device input: \(error)")
    }

    // Add photo output.
    if session.canAddOutput(photoOutput) {
        session.addOutput(photoOutput)

        photoOutput.isHighResolutionCaptureEnabled = true
        photoOutput.isLivePhotoCaptureEnabled = photoOutput.isLivePhotoCaptureSupported
        photoOutput.isDepthDataDeliveryEnabled = photoOutput.isDepthDataDeliverySupported
        livePhotoMode = photoOutput.isLivePhotoCaptureSupported ? .on : .off
        depthDataDeliveryMode = photoOutput.isDepthDataDeliverySupported ? .on : .off

    } else {
        print("Could not add photo output to the session")
        setupResult = .configurationFailed
        session.commitConfiguration()
        return
    }

    session.commitConfiguration()
}

---

我仍然认为videozoomfactor在ios11中被破坏了。有人能证实吗？是的，就是这样！非常感谢你！请参阅下面回答中我的videoZoomFactor代码的位置，以获取Swift-4.2/Xcode 9.0、iOS 11.0 SDK