iOS 8 Snapshotting a view that has not been rendered results in an empty snapshot

In iOS 8 I am having problem capturing images from camera till now I am using this code for

UIImagePickerController *controller=[[UIImagePickerController alloc] init];
controller.videoQuality=UIImagePickerControllerQualityTypeMedium;
controller.delegate=(id)self;
controller.sourceType=UIImagePickerControllerSourceTypeCamera;
[self presentViewController:controller animated:YES completion:nil];

But in iOS 8 I am getting this:

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.

I have tried with the solution provided by This Post with

@property (strong,nonatomic)UIImagePickerController *controller;

_controller=[[UIImagePickerController alloc] init];
_controller.videoQuality=UIImagePickerControllerQualityTypeMedium;
_controller.delegate=(id)self;
_controller.sourceType=UIImagePickerControllerSourceTypeCamera;
_[self presentViewController:controller animated:YES completion:nil];

and this

...
controller.modalPresentationStyle=UIModalPresentationFullScreen;
or
controller.modalPresentationStyle=UIModalPresentationCurrentContext;
...

and this

double delayInSeconds = 0.1;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
    [self presentViewController:controller animated:YES completion:nil];
});

and this

[self presentViewController:controller animated:YES completion:NULL];

and this

[self presentViewController:controller animated:YES completion:^{

}];

any idea?

I'm pretty sure this is just a bug in iOS 8.0. It's reproducible with the simplest of POC apps that does nothing more than attempt to present a UIImagePickerController like you're doing above. Furthermore, there's no alternative pattern to displaying the image picker/camera, to my knowledge. You can even download Apple's Using UIImagePickerController sample app, run it, and it will generate the same error out of the box.

That said, the functionality still works for me. Other than the warning/error, do you have issues with the functioning of your app?

I was struggling with this issue for several hours, i have read every relevant topic and found out that the error was caused because under the privacy settings of my device, the camera access to my app was blocked!!! I have never denied access to camera and i don't know how it was blocked but that was the problem!

I don't have enough reputation points to comment on @greg's answer above, so will add my observations here. I have a Swift project for both iPad and iPhone. I have a method inside my main view controller (relevant bit below). When I test this on a phone, everything works properly and no warnings are generated. When I run it on an iPad, everything works properly but I see the warning about snapshotting the view. The interesting bit, however, is that when I run on an iPad without using the popover controller, everything works properly with no warning. Unfortunately, Apple mandates that the image picker must be used within a popover on iPad, if the camera is not being used.

    dispatch_async(dispatch_get_main_queue(), {
        let imagePicker: UIImagePickerController = UIImagePickerController();
        imagePicker.sourceType = UIImagePickerControllerSourceType.SavedPhotosAlbum;
        imagePicker.mediaTypes = [kUTTypeImage];
        imagePicker.allowsEditing = false;
        imagePicker.delegate = self;

        if(UIDevice.currentDevice().userInterfaceIdiom == .Pad){ // on a tablet, the image picker is supposed to be in a popover
            let popRect: CGRect = buttonRect;
            let popover: UIPopoverController = UIPopoverController(contentViewController: imagePicker);
            popover.presentPopoverFromRect(popRect, inView: self.view, permittedArrowDirections: UIPopoverArrowDirection.Up, animated: true);
        }else{
            self.presentViewController(imagePicker, animated: true, completion: nil);
        }
    });

I ran into this after calling UIImagePickerController presentViewController: from the callback to a UIAlertView delegate. I solved the issue by pushing the presentViewController: call off the current execution trace using dispatch_async.

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
    dispatch_async(dispatch_get_main_queue(), ^{
        UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
        imagePickerController.delegate = self;

        if (buttonIndex == 1)
            imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        else
            imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;

        [self presentViewController: imagePickerController
                           animated: YES
                         completion: nil];
    });
}