Strang flash behaver on AVCaptureDeviceInput - iphone

Question

I use this code to get flash working on the video that i recorded
NSError *error = nil;
// Create the session
AVCaptureSession *session = [[AVCaptureSession alloc] init];
// Configure the session to produce lower resolution video frames, if your
// processing algorithm can cope. We'll specify medium quality for the
// chosen device.
session.sessionPreset = AVCaptureSessionPresetMedium;
// Find a suitable AVCaptureDevice
AVCaptureDevice *device = [AVCaptureDevice
defaultDeviceWithMediaType:AVMediaTypeVideo];
// Create a device input with the device and add it to the session.
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device
error:&error];
[session addInput:input];
// Create a VideoDataOutput and add it to the session
AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init] ;
[session addOutput:output];
// Configure your output.
dispatch_queue_t queue = dispatch_queue_create("myQueue", NULL);
[output setSampleBufferDelegate:self queue:queue];
// Specify the pixel format
output.videoSettings =
[NSDictionary dictionaryWithObject:
[NSNumber numberWithInt:kCVPixelFormatType_32BGRA]
forKey:(id)kCVPixelBufferPixelFormatTypeKey];
[output setAlwaysDiscardsLateVideoFrames:YES];
// If you wish to cap the frame rate to a known value, such as 15 fps, set
//turn flash on
[session beginConfiguration];
BOOL lockAcquired = [device lockForConfiguration:&error];
if (!lockAcquired) {
// log err and handle...
} else {
if ([device hasTorch] && [device hasFlash]){
[device setTorchMode:AVCaptureTorchModeOn];
[device setFlashMode:AVCaptureFlashModeOn];
}
[device unlockForConfiguration];
[session commitConfiguration];
// Start the session running to start the flow of data
[session startRunning];
but there is an strange behavior when recording start , the flash turn on then turn off for less a second then permanently stay on , Did anyone know why and how i solve it ?

Answer 1

Try making AVCaptureSession *session and AVCaptureDeviceInput *input member variables of your class. They need to survive function scope