//切換攝像頭方向
- (void)changeCameraPositionWithCurrentIsFront:(BOOL)isFront {
    if (isFront) {
        [self.session stopRunning];
        [self.session removeInput:self.backCameraInput];
        if ([self.session canAddInput:self.frontCameraInput]) {
            [self.session addInput:self.frontCameraInput];
            [self.session startRunning];
        }

    } else {
        [self.session stopRunning];
        [self.session removeInput:self.frontCameraInput];
        if ([self.session canAddInput:self.backCameraInput]) {
            [self.session addInput:self.backCameraInput];
            [self.session startRunning];
        }
    }

    //解決輸出鏡像問題
    AVCaptureConnection *videoConnection = nil;
    for ( AVCaptureConnection *connection in [self.videoDataOut connections] )
    {
        NSLog(@"%@", connection);
        for ( AVCaptureInputPort *port in [connection inputPorts] )
        {
            NSLog(@"%@", port);
            if ( [[port mediaType] isEqual:AVMediaTypeVideo] )
            {
                videoConnection = connection;
            }
        }
    }

    if([videoConnection isVideoOrientationSupported]) // **Here it is, its always false**
    {
        [videoConnection setVideoOrientation:[UIDevice currentDevice].orientation];
    }
    //設(shè)置前置攝像頭鏡像問題
    [self videoMirored];
}

//攝像頭輸入
- (AVCaptureDeviceInput *)backCameraInput {
    if (_backCameraInput == nil) {
        NSError *error;
        _backCameraInput = [[AVCaptureDeviceInput  alloc] initWithDevice:[self cameroWithPosition:AVCaptureDevicePositionBack] error:&error];
        if (error) {
            NSLog(@"后置攝像頭獲取失敗");
        }
    }
    self.isDevicePositionFront = NO;
    return _backCameraInput;
}

- (AVCaptureDeviceInput *)frontCameraInput {
    if (_frontCameraInput == nil) {
        NSError *error;
        _frontCameraInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self cameroWithPosition:AVCaptureDevicePositionFront] error:&error];
        if (error) {
            NSLog(@"前置攝像頭獲取失敗");
        }
    }
    self.isDevicePositionFront = YES;
    return _frontCameraInput;
}

//獲取可用的攝像頭
- (AVCaptureDevice *)cameroWithPosition:(AVCaptureDevicePosition)position{

    if ([[UIDevice currentDevice].systemVersion floatValue] == 10.0) {
        AVCaptureDeviceDiscoverySession *dissession = [AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:@[AVCaptureDeviceTypeBuiltInDuoCamera,AVCaptureDeviceTypeBuiltInTelephotoCamera,AVCaptureDeviceTypeBuiltInWideAngleCamera] mediaType:AVMediaTypeVideo position:position];
        for (AVCaptureDevice *device in dissession.devices) {
            if ([device position] == position ) {
                return device;
            }
        }
    } else {
        NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
        for (AVCaptureDevice *device in devices) {
            if ([device position] == position) {
                return device;
            }
        }
    }
    return nil;
}