Why can't I see the text in the SKScene?
Is this the right way to have UIScrollView in SKScene?

```
-(id)initWithSize:(CGSize)size {
    if (self = [super initWithSize:size]) {

        UIScrollView * contentScrollView = [[UIScrollView alloc]initWithFrame:self.view.frame];
        contentScrollView.backgroundColor = [UIColor whiteColor];
        [contentScrollView setUserInteractionEnabled:YES];

        UITextView * mainContent = [[UITextView alloc]initWithFrame:self.view.frame];
        mainContent.text = @"HELLO WORLD";
        mainContent.textColor = [UIColor blackColor];

        [contentScrollView addSubview:mainContent];
        [self.view addSubview:contentScrollView];

    }
    return self;
}

```