How do I check for an error after [NSData dataWithContentsOfMappedFile:]?

Question

I have this code in my project:

id mappedData = [dataWithContentsOfMappedFile: path]

Obviously, if mappedData is nil it didn't succeed. But how can I get details about why it didn't succeed? There's no dataWithContentsOfMappedFile:withError:.

Answer 1

Use -dataWithContentsOfFile:options:error:, passing the NSDataReadingMapped constant in the options parameter.

(This constant is known as NSMappedRead if you're not compiling against the iOS 4.0 SDK.)