获取可以设置的焦距值

        let device: AVCaptureDevice = cameraManager.backFacingCamera()
        var arrTitleAll: [String] = []
        if #available(iOS 13.0, *) {
            let arrFactors = device.virtualDeviceSwitchOverVideoZoomFactors
            if arrFactors.isEmpty == false {
                arrTitleAll.append("0.5x")
                for factor in arrFactors {
                    let trueFactor = factor.floatValue * 0.5
                    let strFactor = NSString(format: "%@", NSNumber(value: trueFactor)) as String
                    let title = strFactor as String + "x"
                    arrTitleAll.append(title)
                }
            } else {
                arrTitleAll = ["0.5x", "1x"]
            }
            
        } else {
            arrTitleAll = ["0.5x", "1x"]
        }
        arrBtnFocusTitleAll = arrTitleAll
        btnFocalLength.tag = 1
        changeCameraZoom()

设置焦距

func changeCameraZoom() {
        //调整缩放因子
        let floatValue = ((btnFocalLength.currentTitle ?? "") as NSString).floatValue
        var factor = Float(floatValue)
        factor = factor >= 1 ? (factor * 2) : factor
        cameraManager.setZoom(CGFloat(factor))
        print(CGFloat(factor))
    }

获取当前设备(这部分为就代码，为Objective-C实现)

// 根据位置查找摄像头
- (AVCaptureDevice *)cameraWithPosition:(AVCaptureDevicePosition) position {
    
    if (@available(iOS 13.0, *)) {
        AVCaptureDeviceDiscoverySession * session = [AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:@[AVCaptureDeviceTypeBuiltInTripleCamera, AVCaptureDeviceTypeBuiltInTrueDepthCamera, AVCaptureDeviceTypeBuiltInDualWideCamera, AVCaptureDeviceTypeBuiltInDualCamera, AVCaptureDeviceTypeBuiltInUltraWideCamera, AVCaptureDeviceTypeBuiltInTelephotoCamera, AVCaptureDeviceTypeBuiltInWideAngleCamera] mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionBack];
//        AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithDeviceType:AVCaptureDeviceTypeBuiltInTripleCamera mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionBack];
        NSArray *devices = session.devices;
        AVCaptureDevice *deviceResult = nil;
        for (AVCaptureDevice *device in devices) {
            if ([device position] == position) {
                deviceResult = device;
                break;
            }
        }
        return deviceResult;
    } else {
        NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
        for (AVCaptureDevice *device in devices) {
            if ([device position] == position) {
                return device;
            }
        }
    }
    return nil;
}