UIImagePickerController not taking photos and freezes after I open second time - ios

Question

I have simple singleton class that takes care of creating and presenting UIImagePickerController. It worked just fine until few hours ago. All I did was moving the code from ViewController to separate singleton class (relevant code at the end of post). When I tried to undo all changes to get back to previous state, the problem persisted.
Whenever I present camera, I get warning (not sure if it is related or not)
"Snapshotting a view that has not been rendered results in an empty snapshot. Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates."
Then, when I hit shutter button, nothing happens, no sound, no focus, no photo taken, no callback back to my app.
When I hit cancel, I get the callback and dismiss the controller without problems.
Now when I open camera again, the screen practically freezes, I get the controls and everything, but the screen doesn't update (actually it does, but only once or twice a minute)
#interface AddPhotoManager()
#property (nonatomic, weak) UIViewController *controller;
#property (nonatomic, strong) UIImagePickerController *imagePickerController;
#end
#implementation AddPhotoManager
+ (instancetype)sharedInstance
{
static dispatch_once_t once;
static id sharedInstance;
dispatch_once(&once, ^{
sharedInstance = [[self alloc] init];
});
return sharedInstance;
}
- (void)addNewPhotoFromController:(UIViewController*)controller
{
self.controller = controller;
UIActionSheet *sheet = [[UIActionSheet alloc] initWithTitle:nil delegate:self cancelButtonTitle:#"Cancel" destructiveButtonTitle:nil otherButtonTitles:#"Camera", #"Photo library", nil];
[sheet showInView:self.controller.view];
}
- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
if(buttonIndex == 0 || buttonIndex == 1) {
[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
// Will get here on both iOS 7 & 8 even though camera permissions weren't required
// until iOS 8. So for iOS 7 permission will always be granted.
if (granted) {
// Permission has been granted. Use dispatch_async for any UI updating
// code because this block may be executed in a thread.
dispatch_async(dispatch_get_main_queue(), ^{
[self presentPickerController:buttonIndex == 0];
});
} else {
// Permission has been denied.
}
}];
}
}
- (void)presentPickerController:(bool)camera
{
self.imagePickerController = [[UIImagePickerController alloc] init];
self.imagePickerController.sourceType = camera ? UIImagePickerControllerSourceTypeCamera : UIImagePickerControllerSourceTypeSavedPhotosAlbum;
self.imagePickerController.delegate = self;
[self.controller presentViewController:self.imagePickerController animated:false completion:nil];
}
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
[picker dismissViewControllerAnimated:true completion:nil];
UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
UIImageWriteToSavedPhotosAlbum(image, self, nil, nil);
// TODO: upload the image
self.imagePickerController = nil;
}
- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
[picker dismissViewControllerAnimated:true completion:nil];
self.imagePickerController = nil;
}
The singleton is used simply by calling
[[AddPhotoManager sharedInstance] addNewPhotoFromController:self];
from any view controller
EDIT:
storing imagePickerController in strong property doesn't seem to be necessary, but I wasn't sure so I tried it. However, results are same in both cases.
EDIT 2:
I tried exact same code in new test app and everything worked without problems, so it must be some interference with some other parts of the app? Any ideas what it could be? I tried deleting the app to reset permissions, even changed bundle Id, but nothing helped