ios - 当读取IOS相机的镜头位置时，我得到了这个荒谬的值

在运行iOS 12.1.2的iPhone XS MAX上，将此代码与Swift中的内置WideAngleCamera一起使用：

let lensPos: Float  = AVCaptureDevice.currentLensPosition;
lockCameraForSettings();
self.inputDevice?.setFocusModeLocked(lensPosition: LensPos, completionHandler: { (time) -> Void in})
unlockCameraForShooting();

导致崩溃：
[AVCaptureDevice setFocusModeLockedWithLensPosition:completionHandler:]传递的lensPosition-3402823463852885981170418348451695140000000超出范围[0，1]
摄像机正在运行，并在屏幕预览上清晰可见。它怎么可能处于这种配置中？
在0-1之间插入一个常量是可行的，至少它不会抛出错误。

最佳答案

我相信你的意思是用.lensPosition而不是.currentLensPosition来表示镜头的位置。只有在引用.lensPosition类型的实例时，才能访问AVCaptureDevice。

    var captureDevice: AVCaptureDevice?

    // Plus models and X's
    if let device = AVCaptureDevice.default(.builtInDualCamera,
                                            for: .video, position: .back) {
        captureDevice = device
     // Single Lens devices.
    } else if let device = AVCaptureDevice.default(.builtInWideAngleCamera,
                                                   for: .video, position: .back) {
        captureDevice = device
    } else {
        // No camera was found, is it broke?
        print("Missing expected back camera device.")
    }

    if let device = captureDevice {
        // We have a device, do something with it.
        print(device.lensPosition)
    }