flash light test snippet

gistfile1.m

// from http://stackoverflow.com/questions/11726543/how-to-turn-flashlight-on-off-using-one-button
AVCaptureDevice *flashLight = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    if ([flashLight isTorchAvailable] && [flashLight isTorchModeSupported:AVCaptureTorchModeOn])
    {
        BOOL success = [flashLight lockForConfiguration:nil];
        if (success) 
        {
            if ([flashLight isTorchActive]) {
                [flashLight setTorchMode:AVCaptureTorchModeOff];
            } else {
                [flashLight setTorchMode:AVCaptureTorchModeOn];
            }
            [flashLight unlockForConfiguration];
        }
    }