使用AVCaptureSession切换前/后摄像头

我正在按照SO上的唯一答案 –

用avcapturesession切换相机

但是cameraWithPosition似乎不起作用。 已过时？

//Get new input AVCaptureDevice *newCamera = nil; if(((AVCaptureDeviceInput*)currentCameraInput).device.position == AVCaptureDevicePositionBack) { newCamera = [self cameraWithPosition:AVCaptureDevicePositionFront]; } else { newCamera = [self cameraWithPosition:AVCaptureDevicePositionBack]; } 

Answer 1

您需要做的是重新配置AVCaptureSession

这是我正在使用的：

 // note that `AVCaptureSession * session` // if(session) { [session beginConfiguration]; AVCaptureInput *currentCameraInput = [session.inputs objectAtIndex:0]; [session removeInput:currentCameraInput]; AVCaptureDevice *newCamera = nil; if(((AVCaptureDeviceInput*)currentCameraInput).device.position == AVCaptureDevicePositionBack) { newCamera = [self cameraWithPosition:AVCaptureDevicePositionFront]; } else { newCamera = [self cameraWithPosition:AVCaptureDevicePositionBack]; } NSError *err = nil; AVCaptureDeviceInput *newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:newCamera error:&err]; if(!newVideoInput || err) { NSLog(@"Error creating capture device input: %@", err.localizedDescription); } else { [session addInput:newVideoInput]; } [session commitConfiguration]; } // make sure you have this method in your class // - (AVCaptureDevice *)cameraWithPosition:(AVCaptureDevicePosition)position { NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; for (AVCaptureDevice *device in devices) { if ([device position] == position) return device; } return nil; } 

Answer 2

在Swift 3.0中

 /// Swap camera and reconfigures camera session with new input fileprivate func swapCamera() { // Get current input guard let input = cameraSession.inputs[0] as? AVCaptureDeviceInput else { return } // Begin new session configuration and defer commit cameraSession.beginConfiguration() defer { cameraSession.commitConfiguration() } // Create new capture device var newDevice: AVCaptureDevice? if input.device.position == .back { newDevice = captureDevice(with: .front) } else { newDevice = captureDevice(with: .back) } // Create new capture input var deviceInput: AVCaptureDeviceInput! do { deviceInput = try AVCaptureDeviceInput(device: newDevice) } catch let error { print(error.localizedDescription) return } // Swap capture device inputs cameraSession.removeInput(input) cameraSession.addInput(deviceInput) } /// Create new capture device with requested position fileprivate func captureDevice(with position: AVCaptureDevicePosition) -> AVCaptureDevice? { let devices = AVCaptureDeviceDiscoverySession(deviceTypes: [ .builtInWideAngleCamera, .builtInMicrophone, .builtInDualCamera, .builtInTelephotoCamera ], mediaType: AVMediaTypeVideo, position: .unspecified).devices if let devices = devices { for device in devices { if device.position == position { return device } } } return nil } 

Answer 3

以下是将video会话与交换机配合使用的示例：

 .h UIViewController @property(nonatomic,strong) AVCaptureSession *CaptureSession; @property(nonatomic,strong) AVCaptureMovieFileOutput *MovieFileOutput; @property(nonatomic,strong) AVCaptureDeviceInput *VideoInputDevice; - (void) CameraSetOutputProperties; - (AVCaptureDevice *) CameraWithPosition:(AVCaptureDevicePosition) Position; 

然后：

 .m - (void)viewDidLoad { [super viewDidLoad]; CaptureSession = [[AVCaptureSession alloc] init]; //etc } - (IBAction)CameraToggle:(id)sender { if ([[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] count] > 1) //Only do if device has multiple cameras { NSError *error; //AVCaptureDeviceInput *videoInput = [self videoInput]; AVCaptureDeviceInput *NewVideoInput; AVCaptureDevicePosition position = [[VideoInputDevice device] position]; if (position == AVCaptureDevicePositionBack) { NewVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self CameraWithPosition:AVCaptureDevicePositionFront] error:&error]; } else if (position == AVCaptureDevicePositionFront) { NewVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self CameraWithPosition:AVCaptureDevicePositionBack] error:&error]; } if (NewVideoInput != nil) { [CaptureSession beginConfiguration]; [CaptureSession removeInput:VideoInputDevice]; if ([CaptureSession canAddInput:NewVideoInput]) { [CaptureSession addInput:NewVideoInput]; VideoInputDevice = NewVideoInput; } else { [CaptureSession addInput:VideoInputDevice]; } //Set the connection properties again [self CameraSetOutputProperties]; [CaptureSession commitConfiguration]; } } }