Large UIScrollView with background pattern fails

I have a UIScrollView with a very large content view, it's a bookshelf with around 1000 items on it, when the scroll views content becomes more than around 16000px high it shows a black background and all graphics overlap/blend together.

Here is the sample code

- (void)viewDidLoad {
    [super viewDidLoad];

    开发者_Python百科// Doesn't work
    int sizeForContent = 20000;

    // Does Work
    //sizeForContent = 10000;


    UIScrollView *scroll = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];  

    UIView *subView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, sizeForContent)];
    subView.backgroundColor = [UIColor colorWithPatternImage: [UIImage imageNamed: @"wood.jpg"]];
    [scroll addSubview:subView];
    [subView release];

    scroll.contentSize = CGSizeMake(self.view.frame.size.width, sizeForContent);
    [self.view addSubview:scroll]; 

    [scroll release];

}

Does anyone know why this happens? I assume it is something to do with memory limits but it doesn't seem to be using much memory.

I know I could set the scrollview background color directly instead of adding a subview and setting the background of that but I need to leave the scrollview background as a color.

You can get the basic xcode project from http://cl.ly/2i3F3q0G1j3q433n0f1E if you want to see the issue.

Any help or explanations greatly appreciated.

---

mhm, i also guess that it's a memory problem...

try to avoid this:

 subView.backgroundColor = [UIColor colorWithPatternImage: [UIImage imageNamed: @"wood.jpg"]];

i suppose that when you do that xCode load a small jpg, but then draw it for the whole area of your UIView that at the and will have a big "image" to keep in memory...

try to use just a fill color instead and see if something change...

if so a possible solution could be to use a CATiledLayer for your view, so just the visible portion of your big UIView will be in memory (with the inconvenience that users will see it drawing everytime they scroll around...)

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I also face the same problem. I have a long image, I just want to perform a panaroma effect on that while scrolling. If I used CATiledLayer, will it gives that smoothness. I dont think so will give that smoothness. Because it will draw everytime when it scrolls.I just want to do as the standard iPhone app icons scrolling the Home.

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I solved it by creating view with pattern background, and adding scroll view as subview with [UIColor clearColor] background.