UIAnimation后UI屏幕变黑

我的问题是。。。 我有父视图控制器的对象,我想在上面设置第二个视图控制器的动画。 所以我在parentvc的视图上添加了一个子视图backgroundview。视图,然后是需要在背景视图上绘制的视图。 但在动画完成一秒钟后,我可以看到我想要的视图,但随后它被一个完整的黑屏所取代。

我认为我的最高观点已经被重新画出来了,所以我该如何纠正这个问题。

代码:-

- (void)viewDidLoad {
    [super viewDidLoad];

    //_colorCaptureOptions = [NSArray arrayWithObjects: @"Camera", @"Color Slider / Color Wheel", nil];

    mExtractionQueue = [[NSOperationQueue alloc] init];
    [mExtractionQueue setMaxConcurrentOperationCount:1];


    CGRect screenRect = [[UIScreen mainScreen] bounds];

    //CGRect screenRect = self.view.frame;

    self.backgroundView = [[UIView alloc] initWithFrame:screenRect];
    self.backgroundView.backgroundColor = [UIColor clearColor];

    [self.parentVC addChildViewController:self];
    [self.parentVC.view addSubview:self.backgroundView];
    //[self didMoveToParentViewController:self.parentVC];

    UITapGestureRecognizer *guideTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleScrimSelected)];

    [self.backgroundView addGestureRecognizer:guideTap];
    [self.backgroundView addSubview:self.view];
}

-(void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
        CGRect screenRect = [[UIScreen mainScreen] bounds];

        CGFloat viewHeight = 150;

        self.backgroundView.alpha = 0.0;
        self.view.alpha = 1;
        self.view.frame = CGRectMake(0, screenRect.size.height, screenRect.size.width, viewHeight);


        [UIView animateWithDuration:0.2
                              delay:0
                            options: UIViewAnimationOptionCurveEaseInOut
                         animations:^{
                             self.backgroundView.alpha = 1.0;

                             self.view.frame = CGRectMake(0, screenRect.size.height - viewHeight, screenRect.size.width, viewHeight);
                         }
                         completion:^(BOOL _finished) {
        }];
    }
}