How to access camera flash on UIImagePickerController?

I would like to know how to switch on the camera flash on the iPhone 4 with UIImagePickerController.

if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerCameraDeviceFront] == YES)
{
    /// What code here ///
}
else
{
    NoFlash = [[UIAlertView alloc] initWithTitle:@"Uh-Oh"
                                         message:@"Your device doesn't have a flash camera"
                                        delegate:nil
                               cancelButtonTitle:@"mhmm, OK"
                               otherButtonTitles:nil];
    NoFlash.delegate = self;
    [NoFlash show];
    [NoFlash release];
}

I already read the UIImagePickerController Class Reference web page, but I didn't find the answer. Can someone please help me?

You can use this. Basically call 'toggleTorch' when you want to turn the flash on or off. Hopefully this is what you were looking for.

- (void) toggleTorch {

    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    if ([device hasTorch] && [device hasFlash]){

        if (device.torchMode == AVCaptureTorchModeOff) {

            NSLog(@"It's currently off.. turning on now.");

            [power setImage:[UIImage imageNamed:@"on@2x.png"] forState:UIControlStateNormal];

            AVCaptureDeviceInput *flashInput = [AVCaptureDeviceInput deviceInputWithDevice:device error: nil];
            AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];

            AVCaptureSession *session = [[AVCaptureSession alloc] init];

            [session beginConfiguration];
            [device lockForConfiguration:nil];

            [device setTorchMode:AVCaptureTorchModeOn];
            [device setFlashMode:AVCaptureFlashModeOn];

            [session addInput:flashInput];
            [session addOutput:output];

            [device unlockForConfiguration];

            [output release];

            [session commitConfiguration];
            [session startRunning];

            [self setTorchSession:session];
            [session release];
        }
        else {

            NSLog(@"It's currently on.. turning off now.");

            [power.imageView setImage:[UIImage imageNamed:@"off@2x.png"]];

            [torchSession stopRunning];

        }

    }

}

-(IBAction)powerBtn
{
    [self toggleTorch];
}