If I pass in the annotation view, all I get is what I draw myself in the annotation view, and nothing from the MKMapView background. Even if I draw nothing and the annotation view is 100% transparent and empty, nothing shows up from the MKMapView.

If I pass in the MKMapView, I capture the whole map.

If I pass in the MKMapView but use CGContextClipToRect with the small view's frame or bounds, I get a big image the size of MKMapView, empty but for the clipping rectangle.

If I use UIGraphicsBeginImageContext to make a smaller context matching the small view's size, I only capture the top-left portion of the MKMapView, not the part I want. And calling CGContextClipToRect with the small view's frame just produces an empty image.

Will I have to capture the full map, convert to a bitmap, and extract from that? Is there some other way to do this?

From tests that I have run, it looks like the earliest opportunity to run code happens after the iPhone has cleared away the homescreen and launched your app's splash screen. I'm not sure it's possible to take a screenshot of the icons on the homescreen before your app runs, but if there's a chance, you'll want to see if you can take a screenshot in the entry point function of the app (eg. main).

- (UIImage*)captureView:(UIView *)view bounds:(CGRect)rect
{
UIGraphicsBeginImageContext(CGSizeMake(320, 480));
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextClipToRect(context, rect);
[view.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}

which works just fine.

- (UIImage*)captureView:(UIView *)view bounds:(CGRect)rect
{
UIGraphicsBeginImageContext(CGSizeMake(320, 480));
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextClipToRect(context, rect);
[view.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}

which works just fine.