iOS: idleTimerDisabled = YES works until UIImagePickerController was used

gistfile.m

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    [self dismissViewControllerAnimated:YES completion:^{
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            [UIApplication sharedApplication].idleTimerDisabled = YES;
        });
    }];
}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    self dismissViewControllerAnimated:YES completion:^{
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            [UIApplication sharedApplication].idleTimerDisabled = YES;
        });
    }];
}