uidocumentpickerviewcontroller.m

- (void)documentPicker:(UIDocumentPickerViewController *)controller didPickDocumentAtURL:(NSURL *)url {
    UIImage *receipt = [UIImage imageWithContentsOfFile:url.path];
    
    // BUG: http://www.openradar.me/20447945
    // Skip one run loop to hook up transition coordinator and run action when picker dismissed
    dispatch_async(dispatch_get_main_queue(), ^{
        // iOS < 8.3
        if(controller.transitionCoordinator) {
            [controller.transitionCoordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> context) {
            } completion:^(id<UIViewControllerTransitionCoordinatorContext> context) {
                [self _presentSaveReceiptController:receipt];
            }];
        }
        else { // > iOS 8.3+
            [self _presentSaveReceiptController:receipt];
        }
    });
}