ios - Take a picture on iPhone without showing controls

Question

Is there a way to take a picture in code on the iPhone without going through the Apple controls? I have seen a bunch of apps that do this, but I'm not sure what API call to use.

Answer 1

EDIT: As suggested in the comments below, I have now explicitly shown how the AVCaptureSession needs to be declared and initialized. It seems that a few were doing the initialization wrong or declaring AVCaptureSession as a local variable in a method. This would not work.

Following code allows to take a picture using AVCaptureSession without user input:

// Get all cameras in the application and find the frontal camera.
AVCaptureDevice *frontalCamera;
NSArray *allCameras = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];

// Find the frontal camera.
for ( int i = 0; i < allCameras.count; i++ ) {
    AVCaptureDevice *camera = [allCameras objectAtIndex:i];

    if ( camera.position == AVCaptureDevicePositionFront ) {
        frontalCamera = camera;
    }
}

// If we did not find the camera then do not take picture.
if ( frontalCamera != nil ) {
    // Start the process of getting a picture.
    session = [[AVCaptureSession alloc] init];

    // Setup instance of input with frontal camera and add to session.
    NSError *error;
    AVCaptureDeviceInput *input =
    [AVCaptureDeviceInput deviceInputWithDevice:frontalCamera error:&error];

    if ( !error && [session canAddInput:input] ) {
        // Add frontal camera to this session.
        [session addInput:input];

        // We need to capture still image.
        AVCaptureStillImageOutput *output = [[AVCaptureStillImageOutput alloc] init];

        // Captured image. settings.
        [output setOutputSettings:
        [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG,AVVideoCodecKey,nil]];

        if ( [session canAddOutput:output] ) {
            [session addOutput:output];

            AVCaptureConnection *videoConnection = nil;
            for (AVCaptureConnection *connection in output.connections) {
                for (AVCaptureInputPort *port in [connection inputPorts]) {
                    if ([[port mediaType] isEqual:AVMediaTypeVideo] ) {
                        videoConnection = connection;
                        break;
                    }
                }
                if (videoConnection) { break; }
            }

            // Finally take the picture
            if ( videoConnection ) {
                [session startRunning];

                [output captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {

                    if (imageDataSampleBuffer != NULL) {
                        NSData *imageData = [AVCaptureStillImageOutput 
                                  jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
                        UIImage *photo = [[UIImage alloc] initWithData:imageData];                                                                 
                    }

                }];
            }
        }
    }
}

session variable is of type AVCaptureSession and has been declared in .h file of the class (either as a property or as a private member of the class):

AVCaptureSession *session;

It will then need to be initialized somewhere for instance in the class' init method:

session = [[AVCaptureSession alloc] init]