I had a customer feedback about a "zero length data" error which was captured using an exception handler and displayed using NSAlert.
My app employs [NSURLSession dataTaskWithURL:] to download XML and image data.
But I got no idea what it is about. I assume it's related to NSData, but this error never happened before (for years).
Does anyone have any idea about the source of this error?
captured using an exception handler and displayed using NSAlert.
Don't do that; let the app crash, and then look at the crash logs that Apple will send you. These will include a stack trace so you'll have some chance of identifying the cause.
If you really want to trap fatal exceptions yourself, include more diagnostics.
Anyway, I found out the cause.
The error is thrown when initializing XMLDocument with an empty string:
let xd = try XMLDocument(xmlString: "")