我在阅读IOS摄像头时得到了这个荒谬的值'；镜头位置

在运行iOS 12.1.2的iPhone XS MAX上使用Swift内置WideAngleCamera时使用此代码：

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

导致碰撞：

[AVCaptureDevice SetFocusModelLockedWithLensPosition:completionHandler:]传递的lensPosition-3402834663852885981170418348484516925440.000000超出范围[0，1]'

相机正在运行，并在屏幕预览上清晰地聚焦。它如何可能处于这种配置中

---

在0-1之间插入一个常量值是有效的，至少它不会引发错误。

我相信您的意思是使用

.lensPosition

而不是

.currentLensPosition

，后者是表示镜头位置的特殊常量。只有在引用类型为

AVCaptureDevice

的实例时，才能访问

.lensPosition

    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)
    }

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欢迎新用户，您有一些问题与类型不正确、与浮点、整数等混淆有关。苹果的文档称AVCaptureDevice.currentLensPosition是介于0和1之间的浮点。如果我只做上面显示的第一行，然后调试打印lensPos，我得到：“lens在3.4028235e+38”