iPhone: taking a picture programmatically.

Question

Hello,

I'm trying to use the UIImagePickerController interface from OS 3.1, with the cameraOverlayView and takePicture, but I've clearly failed to understand how this works, and so I'm not getting the behaviour I want.

What I want to do is open the camera and take a picture automatically without having to having the user interact with the picker or edit the image. So I subclass UIImagePickerController (similar to the example in http://github.com/pmark/Helpful-iPhone-Utilities/tree/master/BTL%20Utilities/) and turn off all of the controls:

- (void)displayModalWithController:(UIViewController*)controller animated:(BOOL)animated {
self.sourceType = UIImagePickerControllerSourceTypeCamera;
self.showsCameraControls = NO;
self.navigationBarHidden = YES;
self.toolbarHidden = YES;
    // Setting the overlay view up programmatically.
ipView = [[ImagePickerView alloc] init];
self.cameraOverlayView = ipView;
[controller presentModalViewController:self animated:NO];
}

In the overlayView, I've managed to force the takePicture method of UIImagePickerController to fire (I know this, because I can NSLog it, and I hear the sound of the camera taking a picture). The overlayView shows up just fine. However, the delegate method didFinishPickingMediaWithInfo: never gets called, and imagePickerControllerDidCancel doesn't get called either.

So, how do I either get the delegate methods to get called, or save the picture by overriding the takePicture method? (I have no idea how to capture the picture data here, and Google seems to have failed me). I can't help feeling that I've failed to understand how the guts of UIImagePickerController works, but the docs aren't overly helpful:

e.g.:

"You can provide a custom overlay view to display a custom picture-taking interface and you can initiate the taking of pictures from your code. Your custom overlay view can be displayed in addition to, or instead of, the default controls provided by the image picker interface."

or from showCameraControls:

"If you set this property to NO and provide your own custom controls, you can take multiple pictures before dismissing the image picker interface." - How do I dismiss the picker interface?

Note: the delegate is set properly in IB, so that's not the problem.

Thanks for any help you can provide!

Answer 1

As an update to my own question: It turns out that I was trying to use takePicture too early. When I moved the action to a button on the overlay and sent takePicture from that button (once the picker was presented modally), the delegate methods fired as they should. I don't know if what I wanted is achievable - taking the image without having to press that button, automatically - but if it is, it will probably have to be done by sending takePicture sometime after I was trying to use it.

Answer 2

I've found that you just have to wait "long enough" before calling takePicture, or it just silently fails. I don't have a good answer for how to determine the minimum value of "long enough" that will always work, but if you set a timer and wait five or ten seconds you should be okay. It would be nice if it returned some kind of an "I'm not ready to take a picture yet, sorry" error either directly from takePicture or through the delegate, but as far as I know it doesn't.