UIImage initWithData behaves differently on iOS 4.3

I have an app that's been running fine in the App Store for 6 months or so, but none of its images (downloaded from a web site via "NSURLConnection initWithRequest") show up in iOS 4.3. It turns out that I have a line of code that looks like this:

UIImage *img = [[UIImage alloc] initWithData:data];

and shortly thereafter, to get ready for the next image, I do this:

data.length = 0;

When I comment out setting the length to zero (deferring it until the download of the next image begins), it works on iOS 4.3.

I've checked carefully to make sure there's no buffer interference, but each of my images is in its own instance of an object that has the buffer (data) as an instance variable.

It seems to me that in iOS 4.3 the initWithData impl开发者_JAVA技巧ementation is not completely finished with the data when the method returns. Perhaps some work is being deferred until the UIImage is assigned to the UIImageView, which happens a bit later? Maybe even deferred until the UIImage is rendered?

Can anyone shed light on this seemingly-new behavior in iOS 4.3?

I think your analysis sounds about right. It's easy to imagine the kind of small change that would cause this, for example UIImage may have been changed to retain the data rather than copy it, or something like that. I'd file a bug with Apple to make sure that someone notices the issue, and then work around it by changing your code to:

UIImage *img = [[UIImage alloc] initWithData:[[data copy] autorelease]];

At least, I assume that'd work around it. It'd be very interesting if it doesn't... please let us know one way or the other.