What is the proper way to store an object with many attributes in Objective-C?

What is the proper way to store an object with many attributes in
Objective-C?

I have an object that I am downloading over HTTP, that has approximately
50 attributes. What is the proper way to store this information in
Objective-C? Should I have an NSObject with a property for each attribute
(if so, what would be a good way to initialize this object?)? Should I use
an NSDictionary with 50 key-value pairs?