#pragma mark - 摄像头和相册相关的公共类 // 判断设备是否有摄像头 - (BOOL) isCameraAvailable{ return [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]; } // 前面的摄像头是否可用 - (BOOL) isFrontCameraAvailable{ return [UIImagePickerControllerisCameraDeviceAvailable:UIImagePickerControllerCameraDeviceFront]; } // 后面的摄像头是否可用 - (BOOL) isRearCameraAvailable{ return [UIImagePickerControllerisCameraDeviceAvailable:UIImagePickerControllerCameraDeviceRear]; }

- (BOOL) hasMultipleCameras { NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; if (devices != nil && [devices count] > 1) return YES; return NO; } - (AVCaptureDevice *)cameraWithPosition : (AVCaptureDevicePosition) position { NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; for (AVCaptureDevice *device in devices ) if ( device.position == position ) return device; return nil ; } - (void) swapFrontAndBackCameras { //check for available cameras! if (![self hasMultipleCameras]) return; //assumes session is running NSArray *inputs = self.captureSession.inputs; //should only be one value! for ( AVCaptureDeviceInput *captureDeviceInput in inputs ) { AVCaptureDevice *device = captureDeviceInput.device ; if ( [device hasMediaType:AVMediaTypeVideo ] ) { AVCaptureDevicePosition position = device.position ; AVCaptureDevice *newCamera = nil ; AVCaptureDeviceInput *newInput = nil ; if (position == AVCaptureDevicePositionFront) newCamera = [self cameraWithPosition:AVCaptureDevicePositionBack]; else newCamera = [self cameraWithPosition:AVCaptureDevicePositionFront]; [self initializeCaptureDevice:newCamera]; newInput = [AVCaptureDeviceInput deviceInputWithDevice:newCamera error:nil]; // beginConfiguration ensures that pending changes are not applied immediately [self.captureSession beginConfiguration ]; [self.captureSession removeInput:captureDeviceInput]; //remove current [self.captureSession addInput:newInput]; //add new // Changes take effect once the outermost commitConfiguration is invoked. [self.captureSession commitConfiguration]; break ; } } }