UITextView不滾動，需要幫助

以下代碼片段顯示在正確的背景上，但文本不滾動。UITextView不滾動，需要幫助

我在想什麼？

-(void) viewWillAppear:(BOOL)animated { 

    UITextView *scrollableText = [[UITextView alloc] initWithFrame:CGRectMake(20, 20, 300, 800)]; 
    [scrollableText setOpaque:TRUE]; 
    [scrollableText setBackgroundColor:[UIColor clearColor]]; 

    [scrollableText setEditable:NO]; 
    [scrollableText setText:@"some really really long text"]; 

    [scrollableText setScrollEnabled:YES]; 

    UIImage *backgroundImage = [[UIImage alloc] initWithCGImage:[UIImage imageNamed:@"about_bg.png"].CGImage]; 
    UIImageView *backgroundView = [[UIImageView alloc] initWithImage:backgroundImage]; 

    [backgroundView addSubview:scrollableText]; 

    [[self view] addSubview:backgroundView]; 
}

來源

2011-11-21 JAM