On Feb 13, 2010, at 9:45 PM, PCWiz wrote:
> I have a really simple UIView subclass, all it contains is this:
>
> - (void)drawRect:(CGRect)rect
> {
> CGContextRef ctx = UIGraphicsGetCurrentContext();
> CGContextSetRGBFillColor(ctx, 1.0f, 1.0f, 1.0f, 1.0f);
> CGContextFillEllipseInRect(ctx, CGRectMake(10.0f, 10.0f, 100.0f,
> 100.0f));
> }
>
> It should draw a white circle. To use it, I'm programatically creating the
> view using UIView initWithFrame: then adding it as a subview in my
> UIViewController's viewDidLoad method. The problem is that a black square
> appears behind the circle. I don't know if this is due to the fact that there
> are several CALayers under the view. Any suggestions?
By default views are opaque, and the backing store for the view is likely
filled with zeros (this is not guaranteed, but common) so the view's backing
store is interpreted as a white circle on a black background.
If you set opaque=NO, then you may get white on a clear background, but you can
only guarantee such behavior if you set backgroundColor=[UIColor clearColor];
--
David Duncan
Apple DTS Animation and Printing
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